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Chalcogenocarbonic Acids and Their Anions.

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Chalcogenocarbonic Acids and Their Anions
BY M. DRAGER AND G. GATTOW [*I
Carbonic acids in which the oxygen has been wholly or partly replaced by su[firr, selenium,
and/or tellurium are known as “chalcogenocarbonic acids”. The aim of the present
article is to review existing knowledge of these acids and so establish a basis for jurther
systematic syntheses. The anions required for the synthesis of chalcogenocarbonic acids
will also be briefly characterized.
1. Introduction
dition to form an orthocarbonic acid derivative followed by elimination has for some time been regarded
as conceivable, but no conclusive proof of this course
has yet been found ‘ 2 , 3 J . In acidic media, on the other
hand, the primary step is generally cleavage to form
the starting materials of reaction (1).
Reactions (l), (3), and possibly (4) thus yield the
anion of the acid, so that the only reaction that might
be truly acid-forming is (2). This is the route that has
been taken in all definite preparations of chalcogenocarbonic acids so far. The main problem in further
syntheses of this type is to use a temperature and a
medium such that reaction (2) is sufficiently fast and
the resulting acid thermodynamically stable, or if this
is impossible, to provide a device that rapidly converts the acid into a thermodynamically stable, or at
least metastable, state. Another problem is the purification of a “crude acid” obtained in this way.
The known derivatives of “free carbonic acid
OC(0H)z” and its sulfur, selenium, and tellurium
analogs are numerous, and have been widely studiedcll.
Information on derivatives with acidic hydrogen
bound to 0, S, Se, or Te, with few exceptions, is unsatisfactory, and these compounds have often been
dismissed as unstable without further discussion.
2. Possible Syntheses
There are theoretically four simple possibilities for the
synthesis of chalcogenocarbonic acids.
1. Addition of two molecules to form the desired
chalcogenocarbonic acid, e.g. :
The anions required for the preparation of the acid
are generally obtained by reaction (1) in alkaline
media, e.g.:
2. Addition of protons to the appropriate anion, e.g.:
CS:-
+ 2H+
+ SC(SH)2
cs2+
-H’
-4
csg-
(la)
3. Unsubstituted Trichalcogenocarbonic Acids
3.1. Simple Anions
The only trichalcogenocarbonate ions that have been
definitely detected are those listed in Table 1, dashes
indicate other possible combinations. Salts of the
ions CO:-, C S - , CSe:-, and CSzSe2- can be obtained in the pure state; COzS2- has been detected
polarographically in aqueous solution, COSZ- by UV
spectroscopy in aqueous solution, and CSSe:- by IR
spectroscopy in solid solutions with CSet-.
4. Transchalcogenation of an existing chalcogenocarbonic acid, e.g.:
/
OH
+ H2S
+ S=C,
(4)
SH
Reaction (1) is thermodynamically possible in some
cases, but is sufficiently fast only in alkaline media.
Similarly, reactions (3) and (4) can only be carried out
as direct substitutions in alkaline media; a primary ad-
der Universitat
65 Mainz, Johann-Joachim-Becher-Weg 24 (Germany)
[I] For reviews see: R. Howe in E. H . Rodd Chemistry of Carbon Compounds. 2nd Edit. Elsevier, Amsterdam 1965, Vol. I/C,
868
+ HCS;
(2)
3. Cleavage of ester linkages in a n ester of a chalcogenocarbonic acid, e.g.:
S=C(SH)2+ H 2 0
HS-
Table 1. Trichalcogenocarbonate ions CXf-
0
S
Se
Te
c0;CStCSe:-
CO2S2-
-
CS2Se2-
-
cosf-
-
-
-
cssei-
-
-
-
Angew. Chem. internat. Edit. 1 Vol. 7 (1968) 1 No. I 1
All these ions are formed in accordance with eq. (la)
from C02, COS, CS2, or CSe2 and OH-, SH-, or
SeH--141; corresponding reactions with COSe, CSSe,
CSTe, and HTe- have evidently not yet been attempted.
Carbonates and trithiocarbonates L7--14J have been
known for a long time. The barium115-171 and potassium1151 salts of the CSe:- ion and the barium 115,16,181, potassium"51, and sodium"51 salts of
the CS2Se2- ion have been prepared. Barium salts can
be prepared in aqueous media, while alkali metal
salts are obtainable only in alcoholic solution, with
subsequent precipitation by ether. CSi- occurs, not
only in simple salts with a metal cation, but also frequently as a ligand in complex transition metal anions r19,201. The only crystal structure determination of
a trithiocarbonate that has been reported so far is that
of bis(tetrapheny1arsonium) bis(trithiocarbonato)niccolate(rr)12ll; like COi-- and CSe:-, CS:- is planar.
[4] Contrary to earlier views, Hovenkamp [5] has now been able,
on the basis of a recalculated value of about 10-20 for the
second dissociation constant of H2S, definitely to assign the role
of the acting ion to HS-. For HzSe (K2 = 10-15 [6]), on the
other hand, reaction via the more active Se2- ion cannot be
ruled out.
[5] S . G. Hovenkamp, Dissertation, Delft University 1965.
[6] R. H . Wood, J. Amer. chem. SOC.80, 1559 (1958).
[7] Fundamental work directed to the preparation of trithiocarbonates and perthiocarbonates is described by E. W. Yeoman,
J. chem. SOC.(London) 119, 38 (1921).
[8] Na2CSj and hydrates: P. Silber and M . Maurin, C. R. hebd.
SL-ances Acad. Sci. 247, 602 (1958); M . Maurin, Ann. Chimie 6,
1221 (1961); M . Maurin, Dissertation, Montpellier University,
1962.
[9] K2CS3 and hydrates: M . Maurin, C. R. hebd. S?ances Acad.
Sci. 254, 4470 (1962); M . Maurin and P . Silber, Rev. Chim.
minerale 1, 99 (1964).
[lo] Rb2CS3 and Cs2CS3: P . Silber, E. Philippot, and M . Maurin,
C. R. hebd. Seances Acad. Sci. 261, 4126 (1965).
[ l l ] Ammoniate adducts of alkali metal trithiocarbonates:
M . Maurin, E. Philippot, and P . Silber, C. R. hebd. Seances
Acad. Sci. 262, 110 (1966); E. Philippot, Rev. Chim. minerale 4 ,
643 (1967); E. Philippot, Dissertation, Montpellier University,
1967.
[I21 T12CSj: M. Picon and H . Le Chatelier, C. R. hebd. Seances
Acad. Sci. 195, 1274 (1932); M . Picon, Bull. SOC.chim. France
(4) 53, 248 (1933).
[I31 In2(CS3)3: G. J . Sutton, Roy. Austral. chem. Inst. 3. Proc.
1950, 249.
[141 PbCS3: (1. Gerwarth, Diploma Thesis, Gottingen University,
1965; cf. also [25].
151 H . Seidel, Naturwissenschaften 52, 539 (1965).
[161 N. Hofmann-Bang and B. Rasmussen, Naturwissenschaften
52, 660 (1965).
[171 G. Gattow and M . Druger, Z. anorg. allg. Chem. 348, 229
(1966).
[181 G. Gattow and M . Drager, Z. anorg. allg. Chem., in press.
[19] J. P. Fackler, j r . and D . Coucouvanis, Chem. Commun.
1965, 556; J. Amer. chem. SOC.88,3913 (1966); Proc. 9. int. Conf.
Coordinat. Chem., St. Moritz-Bad 1966, 300; K . N . Johri and
K . Singh, Indian J. appl. Chem. 30, 1 (1967).
1201 D. Coucouvanis and J. P. Fackler, j r . , J. Amer. chem. SOC.
89, 1346 (1967).
I211 J . S . McKechnie, S . L. Miesel, and I. C . Paul, Chem. Commun. 1967,152; E. Philippot and M . Maurin, C. R. hebd. Seances
Acad. Sci. 266, 1290 (1968).
[22] G. Gattow, Naturwissenschaften 45, 623 (1958); 46, 72
(1959); Pure appl. Chem. 2, 121 (1961); E. Philippot and M .
Maurin, C. R. hebd. Seances Acad. Sci. 266, 1499 (1968); K . N .
Johri, N. K . Kaushik, and K . Singh, Current Sci. 36, 458 (1967);
N. K . Kaushik, K . Singh, and K . N . Johri, ibid. 36, 515 (1967).
Angew. Chem. internat. Edit.
I Vol. 7 (1968) No. I 1
Apart from the thermal degradation of some trithiocarbonatesr8--10.221and of BaCSe3 1231, from which the
stability limits of phases having various degrees of
hydration and some enthalpies of formation have been
obtained, and the behavior of the chalcogenocarbonate
ions in aqueous solution (cf. Section 3.3), the main
sources of structural information have been the vibration 124-261 and electronic excitation spectra 1271 of
the ions CO:-, CS:-, and CSei-. In the free state these
ions have D3h symmetry, but their symmetry is decreased in the crystal because of the "site effect".
Spectra of complex saltsi20,281 and lattice vibrations m l have also been studied. The fundamental
vibrations of the ions are given in Table 2.
Table 2. Fundamental vibrations (cm-I), valence force constants fr
(mdynelA), bond numbers N of the C-chalcogen bonds, according to
Sieberr [331, bond lengths rspectr. (A) according to Badger 1351, and
(A) [21, 36, 371 of COi-, CSf-, and CSe:- 1381.
bond lengths
I
vs
I Y
880
505
420
I fr
c0;cs*CS$
j
1
7.66
3.72
3.36
N
1.42
1.16
1.17
I vas
I
I i:; 1
I
I II
1415
j
8
680
320
185
rspectr.
'X-ray
1.30
1.68
I .78
1.294
1.68-1.70
I 82
Complete sets of force constants and mean vibration amplitudes f321 have been calculated from t h e spectra for a general
valence force system [26,301 a n d for a Urey-Bradley potential [*6,31J. Values for t h e valence force constant f r , which is
linearly related t o t h e Pauling electronegativities of t h e atoms
0, S, a n d Se, a r e also shown in Table 2. T h e table also contains t h e b o n d numbers N found from.fr for t h e C-chalcogen
[23] G. Gattow and M . Druger, unpublished.
[24] CO:-: S. D . Ross and J . A. Goldsmith, Spectrochim. Acta
20, 781 (1964), review of earlier literature given therein; J . A.
Goldsmith and S. D . Ross, ibid. 22, 1069 (1966); concerning the
y-vibrations in 13C- and '4C-labeled carbonates, cf. W. Sterzel
and E. Chorinsky, ibid. Part A, 24, 353 (1968).
[25] CSZ-: H . Seidel, Naturwissenschaften 52, 257 (1 965); B.
Krebs, G. Gattow, and A. Miiller, Z. anorg. allg. Chem. 337, 279
(1965); B. Krebs, A. Miiller, and G. Gattow, Z. Naturforsch. 206,
1017 (1965); A. Miiller and M . Stockburger, ibid. 20a, 1242
(1965); A. Miller and B. Krebs, Spectrochim. Acta 22, 1535
(1966).
[26] CSe:-: H. Seidel, Naturwissenschaften 52, 539 (1965); A.
Miiller, G. Gartow, and H. Seidel, Z. anorg. allg. Chem. 347, 24
(1966).
[27] A. Miiller, H. Seidel, and W. Rittner, Spectrochim. Acta
23A, 1619 (1967); A. Miiller and B. Krebs, Mh. Chem. 98, 1540
(1967).
[28] B. Krebs and A. Miiller, Z . Naturforsch. 20a, 1664 (1965);
A. Muller and B. Krebs, Z. anorg. allg. Chem. 345, 165 (1965).
[29] E. E. Angino, Amer. Mineralogist 52, 137 (1967).
[30] C. W. F. T . Pistorius, J. chem. Physics 29, 1174 (1958); J . A.
Ladd, W . J . Orville-Thomas, and B. C . Cox, Spectrochim. Acta
20, 1771 (1964); L . Beckmann, L. Gutjahr, and R . Mecke, ibid. 21,
141 (1965); B. Krebs and A. Miiller, Z. Naturforsch. 20a, 1124
(1965); A . Fadini, A. Miiller, and B. Krebs, ibid. 20a, 1241 (1965);
A. Miiller and A. Fadini, Z. physik. Chem. N.F. 54, 129 (1967);
A . Fadini and A . Miiller, Z. physik. Chem. (Leipzig) 236, 309
(1 967).
[31] G. J . Janz and Y. Mikawa, J. molecular Spectroscopy 5 , 92
(1960); E. C. Curtis, ibid. 17, 108 (1965); 3. Krebs and A. Miiller,
Spectrochim. Acta 22, 1532 (1966).
[32] G. Nagarajan and A. Miiller, 2. Naturforsch.216,393 (1966).
869
bonds[33,341, a s well a s t h e bond lengths rspectr.1351 found
from f;. which can b e compared with rX-ray for C - 0 in
calcite[361, C-S in the bis(trithiocarbonato)niccolate(II)
ion [*11, a n d C-Se in N-benzoyl-N’-phenylselenourea1371.
T h e bands in t h e electronic excitation spectra of t h e ions
Cog-, CSZ-, a n d CSei- in aqueous solution have been
assigned o n t h e basis of a n MO scheme a n d a simple H M O
calculation [271. T h e n-electron densities a n d T-bond orders
obtained from t h e H M O calculation a r e shown in Scheme 1.
T h e x-bond orders vary in t h e opposite direction from
Siebert’s bond number N .
O
\
P
Se
1,753
C 0.741
I
0.558
0
C 0.842
0.570
S
I
OC
’‘
Se 1.718
I
.84 5
0.~570
Se
Scheme 1
Attempts to prepare BaCSSe2rlsl always lead to a
substance whose IR spectrum points to a mixture of
BaCSe3 and BaCSSe2 [391, since the bands remaining
on elimination of the CSe:- spectrum show a logical
relationship to the corresponding bands of the
CS2Se2- ion, and all the bands for both ions can be
assigned without difficulty to the six fundamental vibrations expected for a n ion CXzY having CzVsymmetry [181; these are shown in Table 3 .
Table 3. Fundamental vibrations
of the ions CS,Se2- and CSSeZ(cm-1).
CXlY
CS.Se2- , CSe2S2842
478
299
443
930
335
930
455
193
42 1
898
315
The ions C02S2- and COS$- are the primary products of the reactions of COS and CS2 with OH- ions
in aqueous solution[40,41J;COSi- is also formed on
decomposition of simple xanthates in strongly alkaline mediac31. COS$- can be detected by its char[33] H . Siebert, 2. anorg. allg. Chem. 273, 170 (1953).
1341 The required valence force constant of the corresponding
single bond was also calculated as described by Siebert [33].
[35] R . M . Badger, J. chem. Physics 3, 710 (1935).
[36] R . L. Sass, R . Vidale, and J . Donohue, Acta crystallogr. 10,
567 (1967).
[37] H . Hope, Acta crystallogr. 18, 259 (1965).
[38] The values given for N a n d rspectr. have been recalculated.
1391 A mixture of BaCSe3 and BaCS3, according to [IS]; however, the I R spectra in 1181 clearly show that the product does not
contain BaCS3.
1401 Reaction of COS with OH-: B. Philipp, Faserforsch. u.
Textiltechn. 6, 433 (1955); B. Phiripp and H . Dautzenberg, 2.
physik. Chem. (Leipzig) 229, 210 (1965).
1411 Reaction of CS2 with OH-: E. Treiber, W . Lang, and E.
Mader, Holzforschung 8, 97 (1954), and review of earlier literature given therein; B. Philipp, Faserforsch. u. Textiltechn. 6,433,
509 (1965); M . Wronski, Zeszyty naukowe Uniw. ttrdzkiego,
Ser. I1 2, 107 (1956); Faserforsch. u. Textiltechn. 7, 175 (1956);
8, 32 (1957); Roczniki Chem. (Ann. SOC.chim. Polonorum) 32,
849 (1958); Z . physik. Chem. (Leipzig) 211, 118 (1959); H .
Schmiedeknecht and W. Claus, Faserforsch. u. Textiltechn. 14,
386 (1963); S. G . Hovenkamp, J. Polymer Sci., Part C 2, 341
(1963); Faserforsch. u. Textiltechn. 17, 100, 139 (1966); cf. also
151; B. PhiIipp and H . Dautzenberg, Mber. dtsch. Akad. Wiss.
Berlin 6, 148 (1964); Faserforsch. u. Textiltechn. 17, 1 (1966).
870
acteristic UV absorption at 272 nm, and C02S2- by its
polarographic behavior. Dilute (10-4 M) solutions of
COSi- in 5 N sodium hydroxide solution have an
average lifetime of about 50 hours (at room temperature). More concentrated solutions cannot be prepared, since C0S;- reacts rapidly with an excess of
CS2 to form CS:-. Dilute solutions of C02S2- in 5 N
sodium hydroxide solution, on the other hand, have a
half-life of only about 5 niin at room temperature, but
can be stabilized for a few hours by cooling to -30 “C
(the freezing point of the aqueous solution being
lowered by addition of NaC104). Both ions decompose rapidly in more weakly alkaline solution.
COS- first forms COS, which reacts with OH- to
form C02S2-; CO2S2- decomposes to form SH- and
CO:-. CS2 is not regenerated 140,411.
3.2. Hydrogen Anions HCXJ
Aqueous solutions of the anions listed in Table 1 or
the corresponding acids always contain the monoprotonated anion in the dissociation equilibrium (cf.
Section 3.3). However, since the decomposition of
CO2S2-[401 and CS2-[421,
3
and probably also of
CS2Se2- [18J, proceeds via the hydrogen anions
HCXS, it is not surprising that no salts of any of
these ions have been obtained.
Hydrogen carbonates have been known for a very
long time. However, these do not contain free HCO;
groups, but infinite chains 1431 or dimers [441 held together by hydrogen bonds. The stability of these salts
is therefore primarily due to the strong 0 - H . . . O
bond. HCO, groups that are no longer held together
by hydrogen bonds occur in the crystalline state
when samples of hydrogen carbonate in alkali metal
halide disks are heated to 480 “C 1451; these groups are
retained when the disks are quenched to room temperature, and can be detected by their IR spectrum,
which contains all nine fundamental vibrations of the
HCO; ion. A force constant determination gave
values of 9.12 mdyne/A for the valence force constant
fr[45J, 1.53 for the Siebert bond number “331, and
1.27 A for the length rspectr. of the two free C - 0
bonds 1381.
3.3. Acids
The anions of Table 1 are all fairly stable in strongly
alkaline aqueous solution and in an atmosphere of
nitrogen, whereas they rapidly decompose in acidic
[42] G. Gartow and B. Krebs, Z. anorg. allg. Chem. 323,13 (1963);
S. G. Hovenkamp, Faserforsch. u. Textiltechn. 17, 305, 370, 400
(1966); J. R. Mickelsen and T. H . Norris, Inorg. Chem. 5 , 917
(1966); cf. also [5].
1431 R . L. Sass and R . F. Scheuermann, Acta crystallogr. 15, 77
(1962); R. Brooks and 7‘. C. Alcock, Nature (London) 166, 435
(1950).
1441 C. J . Brown, H . S . Peiser, and A. Turner-Jones, Acta crystallogr. 2, 167 (1949); G . E. Bacon and N . A . Curry, ibid. 9, 82
(1956); I. Nitta, Y. Tomiie, and C . H . Koo, ibid. 5, 292 (1952);
P. Herpin and P. Meriel, J . Physique 25, 484 (1964); B. Pedersen,
Acta crystallogr. B 24, 478 (1968).
[45] D . L . Bernitt, K. 0 . Hartman, and I. C . Hisatsune, J . chem.
Physics 42, 3553 (1965).
Angew. Chem. internat. Edit.
Vol. 7 (1968) 1 No. I 1
solution via the undissociated acid or the hydrogen
anion. c.g.:
H20
+ C02
+ COz
H2C03
+
HC02S-
+ HS-
HzCOSz
+ H2S
HCS;
+
HCS2Se-
+ HSe-+
H2CSe3
+ H2Se + polymeric C-Se products
HS-
(5)
(6)
+ COS
+ CS2
(7)
CS2
(9)
(1 0 )
reaction of the hydration of COz, has been very extensively studied because of its practical importance1461. Reactions (6) and (7), which are also very
fast, have not yet been followed in acidic solution140,411. The rapidity of reactions ( 5 ) to (7) makes
it impossible to obtain these acids from the aqueous
phase.
The same is true of HzCSe3, which has a half-life of
15 sec in 10-3 M solution at 0 "C and so permits conductivity measurements, but decomposes very rapidly
in more concentrated solutions to form C-Se polymers that have not yet been studied in detail [reaction (10)][17,471. Thus H2CSe3 also cannot be obtained from aqueous solution. H2CS3 [421 and
H2CS2Se[lsl, on the other hand, decompose via their
hydrogen anions, and are therefore so stable in fairly
concentrated strongly acidic solution that the free
acids can be precipitated from aqueous solutions of
their salts owing to their low solubility in water.
Extensive measurements on aqueous solutions of the
salts and the free acids have led to the values given in
Table 4 for the electrolytic dissociation constants; the
constants for perthiocarbonic acid HzCS4 [491 are also
given for comparison.
Table 4. Dissociation constants K1 at 0 "C and K Z at 25 "C
Ki
Kz
1
H2C03 [48]
1.55 x 10-4
4.69 x 10-11
I
I
H2CS3 (421
1.2 [a]
1.2 x IO-?[a]
[a] Value for 20 'C.
I
I
H2CSe3 [47]
6.9
6.9
Y
Y
10-2
10-8
I
1
1
H2CS2Se[I84 H2C& [491
1.2 Y 10-5
1.0 > IO-lI
2.8 x 10-4[bl
5.75 Y 10-8
[b] Value for 2 ° C
Free H2CS3 is formed on reaction of an aqueous suspension of BaCS3 with hydrochloric acid at 0°C. It
occurs as a red oil, which can be separated from the
aqueous phase without appreciable decomposition,
dried, and stored at --78 "C[501. Many physical and
thermodynamic constants of the substance, which
solidifies at -26.9 "C, have been determined r503511.
[46] D. M . Kern, J. chem. Educat. 37, 14 (1960): comprehensive
summary of the reactions occurring between COz, H20, H2CO3,
HCO; und COZ-; cf. also [66].
[47] G. Gattow and M . Drager, Z . anorg. allg. Chem. 349, 202
(1967).
[48] K . F. Wissbrun, D . M . French, and A . Patterson, J. physic.
Chem. 58, 693 (1954); H . S. Harned and S . R. Scholes, J. Amer.
chern. SOC.63, 1706 (1941).
[49] G. Gattow and J . Wortmann, Z . anorg. allg. Chem. 345, 137,
172 (1966).
[SO] G. Gattow and B. Krebs, Z . anorg. allg. Chem. 321, 143
(1963).
A n g e w . C h e m . internat. Edit. 1 Vol. 7 (1968) 1 No. I 1
1
Table 5 . C-S distances in solid
(8)
( 5 ) is a very fast reaction, which, like the slow reverse
I
An X-ray structural analysis at -100°C showed that
solid H2CS3 exists in the form of isolated molecules,
which are joined by hydrogen bonds to form double
spirals with alternating left-hand and right-hand
twists. The CS3 group is planar, and the various C-S
distances are given in Table 5 .
C=S
C-S-H
C-S-H
HKS3 at -lOO°C
1521.
S as H-bond acceptor
S as H-bond donor
S not bound by H bond
The hydrogen bonds in solid and liquid H2CS3 are
indicated in the IR systern[50,531 by an S-H stretching
band at about 2500 cm-1, which is replaced by a sharp
split band at 2550 cm-1 in dilute solutions of H2CS3
in cc14, in which the H bonds are broken. The other
I R bands have been assigned to the fundamental vibrations of the SC(SH)2 molecule 1541. HMO calculations[54,551for the CS3 skeleton of the acid give thexelectron densities andx-bond orders shown in Scheme2.
S"
/
\
1.849
0,436
sl
1.559
0.745
C 0.743
0.436
S"
1.849
Scheme 2.
HzCS3 is o f little importance a s a reagent i n preparative
chemistry. T h e only known reactions in which t h e CS3
grouping is retained a r e t h e reaction with oxalyl chloride t o
form 4,5-dioxo-2-thioxo-l ,3-dithiolane 1561, the reaction with
chlorosulfanes S,C12 t o form (CS3+& ( n a b o u t 10, x = 1 t o
6)[571, a n d t h e oxidation by bromine at -3OOC t o give
(CS3)n[5R1 ( n a b o u t 9). T h e products obtained in all other
cases a r e also obtainable by similar reactions with H2Sr621.
However, HzCS3 is frequently m o r e reactive [591. Heavy metal
1511 G. Gattow and B. Krebs, Z. anorg. allg. Chem. 322, 113
(1963).
[52] B. Krebs and G. Gattow, Naturwissenschaften 5 1 , 554
(1964); Z . anorg. allg. Chem. 340, 294 (1965).
1531 P. A. Tire and D . B. Powell, Spectrochim. Acta 21, 835
(1965).
1541 A . Miiller, B. Krebs, and G. Gattow, Z. anorg. allg. Chem.
349, 74 (1967).
[55] J . Fabian, A. Mehlborn, A . Bormann, and R . Mayer, Wiss. Z .
Techn. Univ. Dresden 14, 285 (1965).
[56] B. Krebs and C. Gattow, Angew. Chem. 75, 978 (1963); Angew. Chem. internat. Edit. 2,618 (1963); A . Muller, B. Krebs, and
R. Ahlrichs, Z . Naturforsch. 2 l b , 389 (1966).
[57] M. Schmidt, Angew. Chem. 73, 394 (1961).
[58] B. Krebs and G . Gattow, Z . anorg. allg. Chem. 338, 225
(1965). Polymeric (CS2.& with n = 8-9 was also obtained by
reaction of NaZCS3 or Na2S with thiophosgene.
[59] Compare the formation of dimeric and polymeric thiomalonic anhydride on reaction with malonyl chloride [60] and
the reaction with dimeric thiophosgene to form 4,4-dichloro-1,3dithia-2-cyclobutanethione [61], which affords derivatives of
ditrithiocarbonic acid with NazS, thiols, o r amines 1611.
1601 B. Krebs and G. Gattow, Angew. Chem. 78, 210 (1966);
Angew.Chem. internat. Edit. 5 , 250 (1966).
[61] J . Wortmann, G.Kie1, and G.Gattow,Z . Naturforsch., in press.
[62] Thiosuccinic anhydride [63], very pure A12S3 [63], thiophthalic anhydride [61], chlorothiolacetic acid [61], thiolterephthalic acid [61], thiolisophthalic acid 1611.
[63] B. Krebs and G. Gattow, Angew. Chem. 77, 1086 (1965);
Angew. Chem. internat. Edit. 4, 1090 (1965).
87 I
trithiocarbonates can be readily obtained in t h e pure state by
reaction of the acetates with HzCS3 in dimethyl sulfoxide"41.
chalcogen atoms. The most extensively studied of
these compounds are the ethyl derivatives.
Like H2CS3, free H2CS2Se can be obtained by reaction of an aqueous suspension of the barium salt
with hydrochloric acid [181. It is a bluish-red oil, which
cannot be obtained in the pure state owing to rapid
decomposition, but can only be separated by dissolution in a stabilizing organic phase. It is stable at low
temperatures in this phase after drying. HzCSzSe
probably exists in the asymmetric form ( I ) , since only
H2Se and CS2 can be detected when it decomposes,
and methylation of CS2SeZ- yields the asymmetric
dimethyl ester (2) 1641.
C02-ORCOS-OR[COI-SR-I
CSz-ORCOS-SRCS,-SR-
[CO(OH)-OR]
-
[CO(OH)-SRI
CS(SH)-OR
-.
CS(SH)-SR
[CO(SeH)-OR]
[CS(SeH)- OR1
-
,S-H
(I)
s=c,
Se-H
,S-CHs
s=c,
Se-CH3
The other trichalcogenocarbonic acids, on the other
hand, can be prepared only in nonaqueous solution,
i.e. from the anhydrous salts, so that HzC02S and
H2COS2, whose anions are known only in aqueous
solution, have not yet been obtained.
Free carbonic acid is formed as the dimethyl ether
monoadduct HzC03.O(CH3)2 on reaction of dry
Na2C03 with HC1 in dimethyl ether at -35°C; the
excess of dimethyl ether is evaporated off under
vacuum at -80 "C [65,661. The white crystalline adduct
melts at -47°C with polymerization, and decomposes at temperatures )-26 "C to give H20, COz, and
O(CH3)z. 1H-NMR studies have shown the presence
of C - 0 - H protons[661. A number of thermodynamic
constants have been determined from vapor pressure
measurements 165-671. A monoadduct with diethyl ether
reported earlier [681 could not be definitely confirmed
by other investigatorsr661. The description of the experiment 1681 suggests the presence of an addition
compound having a variable composition 1691.
Similar experiments on a suspension of BaCSe3 in diethyl ether with HCI at -30°C lead to the formation
of a dark red, highly viscous oil, which decomposes
very rapidly above -10 "C [171. Owing to low solubility
in organic solvents, it has not yet been possible to
separate H2CSe3 from BaCI2 formed at the same time.
4. Monoalkylated Trichalcogenocarbonic Acids
The various types of monoalkyl trichalcogenocarbonic acids and trichalcogenocarbonates are listed in
Table 6. The alkyl group may be bound to different
1641 M. Drager and G . Gattow, unpublished
[65] G . Gartow and U. Gerwarth, Angew. Chem. 77, 132 (1965);
Angew. Chem. internat. Edit. 4,149 (1965).
[66] G . Gattow and U . Gerwarfh, Z . anorg. allg. Chem. 357, 78
(1968).
[67] Calculation of thermodynamic functions for the ideal gas
state from assumed molecular parameters: A . A . Antonov and
P . C. Maslov, Russ. J. inorg. Chem. (Engl. transl. of 2. neorg.
Chim.) 38, 318 (1964).
1681 A . G . Galinos and A . A . Carotti, J. Amer. chem. SOC.83, 752
(1961).
[69] W. Hempel and J . Seidel, Ber. dtsch. chem. Ges. 31, 2997
(1898).
872
CSSe-ORCSe2-OR-
(2)
4.1.Anions
Monoalkyl trichalcogenocarbonates are generally
prepared by reaction of C02, COS, CS2, CSSe, and
CSez with alkoxides or thiolates "1; reactions with
selenolates or tellurolates have not yet been examined.
Transesterifications and partial hydrolyses of dialkyl
compounds can also be used.
Alkyl carbonates in aqueous solution exist in the
equilibrium
R-0-CO;
+
H20
;=i
HCO;
+
R-OH
The equilibrium constant at 0 ° C is K = 12 for the
methyl compound and K = 23 for the ethyl compoundr701. Salts can therefore only be obtained in alcoholic solutions. In acidic and in alkaline media,
the equilibrium is strongly displaced toward the decomposition products; equilibrium is reached very
rapidly in acidic solution, but slowly in alkaline solution 1701. Whereas alkaline earth metal alkyl carbonates
have high C02 partial pressures, dry alkali metal
salts are very stable[7ol. Alkyl carbonates are used
as carboxylating agents [7*, 721.
0-Alkyl monothiocarbonates are formed when COS
is passed into alcoholic alkoxide solutions [I]; the
best known of these compounds is potassium 0-ethyl
monothiocarbonate (Bender's salt) 2731. These compounds decompose rapidly in aqueous solution via
[70] C . Faurholt, Z . physik. Chem. 126, 72, 85, 211, 227 (1927);
C . Faurholf and I. C . Jespersen, ibid. 165, 79 (1933); C . Faurholt,
K . Noiesen, and F. Rath, Dansk. Tidskr. Farmaci 11, 267 (1937);
C . Faurholt and K. P . Hansen, ibid. 16, 73 (1942); C. Faurholt and
J. C . Gjaldbaek, ibid. 17, 213 (1943); 19, 255 (1945); V. Lund,
J . C. Gjaldbaek, and C. Faurholt, ibid. 21, 243 (1947); H. Soling
and C. Faurholt, ibid. 25, 89 (1951).
[71] J . I. Jones, Chem. and Ind. 1958, 228.
[72] M. Stiles, Ann. New York Acad. Sci. 88, 332 (1960); K .
Winterfeld and H . Buschbeck, Arch. Pharmaz. 294, 468 (1961);
R . F. Ruthruff, U.S. Pat. 3038006 (June 5, 1962); U.S. Pat.
3102906 (Sept. 3, 1963); G. D. Buckley, British Pat. 940371
(Oct. 30, 1963) ICI; H . L. Finkbeiner and G . W. Wagner, J. org.
Chemistry 28, 216 (1963); H . L. Finkbeiner, J. Amer. chem. SOC.
87, 4588 (1965). For the formation of high polymers from unsaturated monoalkyl carbonates, cf. F. Pochetti, Rass. chim. 11,
232 (1965).
[73] C. Bender, Liebigs Ann. Chem. 148, 137 (1868) regarding
the rate of the reaction COS-ethanol, cf. B. PhiZipp and H.
Dautzenberg, Z . physik. Chem. (Leipzig) 231, 270 (1966).
Angew. Chem. internat. Edit. / Vol. 7 (1968)1 No. 11
the free 0-ethyl monothiocarbonic acid. The rate of
decomposition consequently decreases steadily above
pH - 9, while i t rapidly increases below this p H
value 13.741. IR spectroscopic data for the alkyl monothiocarbonates are given in Table 7 [751. S-Alkyl monothiocarbonates are much less stable, and have so far
been obtained only in solution. They are formed from
alkyl carbonates on transesterification with thiolates L711.
examination of t h e IR spectrumr80,811 (see Table 7), no
definite distinction could b e m a d e between C = S a n d C-0-C
vibrations, which couple strongly with o n e another. T h e
electronic excitation spectrum contains strong absorption
maxima a t 301 a n d 226 n m [821.
YCO
1570-1580
0-Alkyl dithiocarbonates, which are generally known
as xanthates, are the most extensively studied and the
(technically) most important group of alkyl chalcogenocarbonates. They are formed by reaction of CS2
with alkoxides 1 761. Xanthates are relatively stable
in aqueous solution between pH 7 and pH 14r31, but
decompose rapidly outside this range 177,781. The decomposition in acidic solution [771 proceeds via the
free xanthic acid with formation of alcohol and CS2
(cf. Section 4.2), while that in alkaline solution [781,
proceeds via a dithiocarbonate to give sulfide and
carbonate.
V c s
1025-1040
1020-1070
"CSe
YCOC
1090-1120
1100-1280
Crystal structure determinations "91 have shown t h a t t h e
ionic alkali metal xanthates consist of isolated cations a n d
xanthate groups, while t h e xanthates of arsenic a n d antimony,
a s well a s of t h e transition metals, have complex molecules in
which t h e xanthate sulfur has a square-planar arrangement
a r o u n d MI1 or a distorted octahedral arrangement a r o u n d
M""so1. T h e t w o C-S bonds in t h e ionic xanthates a r e equivalent (C-S = 1.68 A), whereas t h e complex xanthates contain
o n e short (1.56-1.65 A) a n d one long (1.70-1.79 A) C-S
bond. T h e CS20 portion is planar in all t h e xanthates. On
[74] M . Wronski, Faserforsch. u. Textiltechn. 10, 46 (1959).
[75] F. G. Pearson and R. B. Stasiak, Appl. Spectroscopy 12, 116
(1958).
[76] Concerning reaction of formation, cf. M . Wronski, Roczniki
Chem. (Ann. SOC.chim. Polonorum) 33, 1061 (1959); Z. physik.
Chem. (Leipzig) 211, 113 (1959) as well as [ S ] .
[77] Decomposition of xanthate in acid medium: H. v . Halban
and W . Hecht, Z. Elektrochem. angew. physik. Chem. 24, 65
(1918); C. V. King and E. Dublorr, J. Amer. chem. SOC.54, 2177
(1932); A . Chatenever and C. V . King, ibid. 71, 3587 (1949); A. C.
Cranendonc, Recueil Trav. chim. Pays-Bas 70, 431 (1951); I. Iwasaki and S. R. B. Cooke, Mining Engng. 9, 1267 (1957); J. Amer.
chem. SOC.80, 285 (1958); J. physic. Chem. 63, 1321 (1959); 68,
2032 (1964); E. Klein, J. K . Bosarge, and I. Normann, ibid. 64,
1666 (1960); R. Zahradnik, 2. physik. Chem. (Leipzig) 213, 318
(1960); B. Toernell, Svensk Papperstidn. 69, 658, 695 (1966);
V. Hejland F. Pechar, Chem. Zvesti 21, 261 (1967), as well as 131.
[781 Decomposition of xanthate in alkaline medium: M . Wronski,
Zeszyty naukowe Uniw. Lbdzkiego, Ser. I1 3, 177 (1957); Z.
physik. Chem. (Leipzig) 211, 113 (1959); H . J . Bur, H . Dantzenberg, and B. Philipp, Z. physik. Chem. (Leipzig) 237, 145 (1968),
as well a s [3].
[79] Crystal-structure determination of xanthates: K ethyl:
F. Mazzi and C. Tadini, Z. Kristallogr. Kristallgeometr., Kristallphysik, Kristallchem. 128, 378 (1963); As ethyl: G. Carrai and
G. Gottardi, ibid. 113, 373 (1960); S b ethyl: G. Gottardi, ibid. IIS,
451 (1961); Ni ethyl: M . Franzini, ibid. 118, 393 (1963); Moethyl
(binuclear): A . B. Blake, F. A . Cotton, and J . S. Wood, J . Amer.
chem. SOC.86, 3024 (1964); Cd n-butyl: H . M . Rietveld and E. N .
Maslen, Acta crystallogr. 18, 429 (1965); Zn ethyl: T. Ikeda and
H. Hagihara, ibid. 21, 919 (1966); Pb ethyl: H. Hagihara and
S. Yamashita, ibid. 21, 350 (1966); P b n-butyl: H. Hagihara and
Y. Watanabe, ibid. B 24, 960 (1968); Te ethyl: S . Husebye, Acta
chem. scand. 21, 42 (1967).
[801 Preparation and 1R spectrum of complex transition metal
xanthates: G. W. Watt and B. J . McCormick, J. inorg. nuclear
Chem. 27, 898 (1965); Spectrochim. Acta 21, 753 (1965); U.Agarwala, Lakshmi, and P. B. Roo, Inorg. chim. Acta 2, 337 (1968).
For the strength of the ligand field, cf. the N M R measurements
o n 59Co complexes: C . R . Kanekar, M . M . Dhingra, V. R. Marathe, and R . Nagarajan, J. chem. Physics 46, 2009 (1967).
Angew. Chent. internat. Edit.
/ VoI. 7 11968) No. I I
1560
950-960
1000-1050
940-950
The S-alkyl dithiocarbonates are also much less
stable than the 0-alkyl compounds. They are formed
on careful hydrolysis of 0,s-dialkyl dithiocarbonates
with tertiary amines in organic solvents below room
temperature 1831, and decompose in aqueous solution
into COS and alkanethiols.
The alkyl trithiocarbonates, which are obtained by
reaction of alkanethiolates with CS2 [I], form salts
that are relatively stable even in aqueous solution[s13821.
Alkyl selenocarbonates corresponding to the xanthates, i.e. 0-alkyl thioselenocarbonates 1851 and 0alkyl diselenocarbonates 1%) have been obtained in the
form of their alkali metal salts by reaction of alkoxides
with CSSe or CSe2. These salts form yellow crystals,
and are stable only under nitrogen, in the absence of
light, and at low temperatures. CSe2 reacts vigorously
with cellulose to give cellulose selenoxanthate, the
rapid formation of which is followed by equally rapid
decomposition 1x71.
4.2. Acids
The xanthic acids 1891 and the trithiocarbonic acids 1901
can be precipitated from aqueous solutions of salts
181J Review of the IR spectra of xanthates, alkyl trithiocarbonates, and dithiocarbamates: M . L . Shankaranarayana and C. C .
Patel, Spectrochim. Acta 21, 95 (1965); D . Coucouvanis and J.P.
Fackler, j r . , Inorg. Chem. 6, 2047 (1967).
[82] Review of the UV spectra of xanthates, alkyl trithiocarbonates, and dithiocarbamates: M . L. Shankaranarayana and C. C.
Patel, Acta chem. scand. 19, 1113 (1965).
[83] H. Yoshida and S . Inokawa, J. chem. SOC. Japan, pure
Chem. Sect. (Nippon Kagaku Zasshi) 86, 950 (1965); H . Yoshida,
S . Inokawa, and T. Ogata, ibid. 86, 1179 (1965); 87, 1209, 1212
(1966); Bull. chem. SOC.Japan 39, 411 (1966).
I841 Recorded for tetramethylammonium S-methyl dithiocarbonate. We are grateful to H . Yoshida, Hamamatsu, for supplying the substance.
[ 8 5 ] A. Stock and E. Willfroth, Ber. dtsch. chem. Ges. 47, 144
(1914).
[86] A. Rosenbaum, H . Kirchberg, and E. Leibnitz, J. prakt.
Chem. (4) 19, 1 (1963); A. Rosenbaum, ibid. 37, 200 (1968);
Bergakademie, Freiberger Forschungsh. Ausg. A 328, 59 (1964).
[87] E. Treiber and J. Rehnstrom, Papier 12, 274 (1958).
[881 K . A . Jensen, J. B. Carlsen, A. Holm, and P. H . Nielsen,
Acta chem. scand. 17, 550 (1963).
[891 Xanthic acids: methyl: [531; ethyl: H . v . Halban and A.
Kirsch, Ber. dtsch. chem. Ges. 45, 2418 (1912); Z. physik. Chem.
82, 325 (1913); n-propyl: S. Scala, Gazz. chim. ital. 17, 79 (1887);
isoamyl: 0. L. Erdmann, J. prakt. Chem. (I) 31, 4 (1844); ailyl:
B. Odd0 and G. del Rosso, Gazz. chim. ital. 39, 1 5 (1909);
benzyl: 1771.
1901 Alkyltrithiocarbonic acids: methyl: [53]; ethyl: B. Holmberg, J. prakt. Chem. (2) 73, 239 (1906); p-chlorobenzyl and
p-bromobenzyl: H. v . Halban, A. Mackert, and W. Ott, Z. Elektrochem. angew. physik. Chem. 29, 445 (1923).
873
of alkyl trichalcogenocarbonic acids by dilute hydrochloric acid or sulfuric acid. They separate out as oily
liquids or even in the crystalline form, and can be isolated without difficulty. The rate of decomposition of
the other alkyl chalcogenocarbonates in acidic media
is so high, on the other hand, that the free acids cannot
be obtained from aqueous solution.
Distillation of liquid COz into alcohols a t -50OC under
pressure yields compounds having t h e empirical formulas o f
alkyl esters of carbonic acid1691 (the methyl, ethyl, propyl,
tert-butyl, a n d amyl compounds have been prepared). However, these a r e probably addition compounds rather t h a n
free alkyl carbonic acids, since a reaction between CO2 a n d
alcohol under these conditions is very unlikely. Equally improbable is t h e formation o f a stable solid S-ethyl thiocarbonic
acid by oxidation o f ethylthioacetylene with 30% H202 in
glacial acetic acid o n heating [911. 0-Ethyl selenocarbonic
acid is reported to be formed on reaction o f ethyl chloroformate a n d magnesium hydrogen selenide bromide a s
colorless needles having m.p. 122-123 "C [921.
5.1. Chalcogenocarbamic Acids
Chalcogenocarbaniic acids in general are prepared by
reaction of their salts, the chalcogenocarbamates 1951,
with acids. Ammonium or alkylammonium salts are
readily obtained by reaction of C02, COS, CS2, or
CSe2 with ammonia or amines 11,*6,96-991. In addition
to a number of IRr81,loOl and UV182,1011 spectroscopic studies, special mention should be made of the
numerous crystal structure determinarions of a wide
range of dithiocarbamate complexes [lo?]. In these
complexes, in contrast to the xanthate complexes, the
two C-S bonds generally appear, to a close approximation, to be equivalent (C-S == 1.68-1.71 A).
This tendency to form equivalent C-chalcogen bonds
in the form of a zwitterion is also found in the free
acids. However, extensive decomposition measure-
Free selenoxanthic acid is formed on acidification of
aqueous monoselenoxanthate solution as an oil that
decomposes rapidly with formation of selenium 1851.
Xanthic acids are very stable in the perfectly pure
state or in apolar solvents even at 50 "C [89,931. Even
traces of polar substances, however, cause decomposition into CS2 and alcohol, which further accelerates
the decomposition autocatalytically. Extensive measurements on the decomposition kinetics [771 have
shown that the first step in the decomposition of the
acid is the formation of an active zwitterionic complex. The rate of decomposition of the xanthic acids
decreases again in strongly acidic solution, since they
are then present in the protonated form. The dissociation constant of ethylxanthic acid is 0.023 at 0 "C and
0.027 at 25 "C [771.
Pure xanthic acids and alkyl trithiocarbonic acids contain intermolecular hydrogen bonds 1531, which are
broken in solutions of the acids.
High molecular weight cellulosexanthic acid is formed
as the initial product in the reaction of cellulose xanthate with acids in aqueous solution [941. The decomposition can be followed by measurement of the UV
absorption at 270 nm; the dissociation constant is
about 0.05.
5. Chalcogenocarbonic Acids Containing
Nitrogen
Known chalcogenocarbonic acids containing nitrogen
are carbamic acids, carbazic acids, and isocyanic acids.
,NHZ
x=c,
XH
NH-NHz
x=c,
H- N=C=X
XH
[91] R. Adams and A. Ferretti, J. Amer. chem. SOC. 81, 4927
(1959).
[92] Q. Mingoia, Gazz. chim. ital. 58, 670 (1928).
I931 G. M . Lewis, Dissertation, New York University, 1947
I941 H. Jost and J. Ludwig, Faserforsch. u. Textiltechn. 17, 29,
194 (1966); 18, 274 (1967).
874
ments in aqueous dithiocarbamate solutions have
shown [I031 that their decomposition begins with a
zwitterionic form of this type, so that the rate of decomposition of the chalcogenocarbamic acids increases rapidly with increasing N-alkylation (and
[951 Cf. W. Haasand K . Irgolit, Z . analyt. Chem. 193,248 (1963).
[96] Literature review on salts of carbamic, monothiocarbamic,
and dithiocarbamic acids: R. Zahradnik, Chem. Techn. 1I , 546
(1959). Regarding the kinetics of the formation reaction, cf.
M. M. Sharma, Trans. Faraday SOC. 61, 681 (1965); P. J . Kothari
and M . M . Sharma, Chem. Engng. Sci. 2!, 391 (1966); B. Philipp
and H . Dautzenberg, Faserforsch. u. Textiltechn. 19, 23 (1968).
[97] Review on esters of carbamic acid: P. Adams and F. A.
Baron, Chem. Reviews 65, 567 (1965).
[98] Diselenocarbamates: D. Barnard and D . T. Woodbridge, J .
chem. SOC. (London) 1961, 2922; G. M. C . Higgins and B. Saville, ibid. 1963, 2812; K . A. Jensen and V . Krishnan, Acta chem.
scand. 21, 2904 (1967); B. Lorenz and E. Hoyer, Z . Chem. 8, 230
(1968); C. Furlani, E. Cervone, and F. Diomedi, Camassei, Inorg.
Chem. 7 , 265 (1968); cf. also [86].
1991 G . D. Thorn and R. A. Ludwig: The Dithiocarbamates and
Related Compounds. Elsevier, Amsterdam 1962. Regarding the
use of chalcogenocarbamates as herbicides, fungicides, and
insecticides, cf. G. Scheurer, Fortschr. chem. Forsch. 9,254 (1967);
B. Nase, Z. Chem. 8,96 (1968).
[IOO] R. A. Nyquist and W. J . Potts, Spectrochim. Acta 17, 679
(1961); D . L. Frasco, J. chem. Physics 41, 2134 (1964); K . Nakamoto, J. Fujita, R. Condrate, and Y. Morimoto, ibid. 39, 423
(1963) as well as [ 8 8 ] .
[loll E. Svatek, R . Zahradnik, and A . Kjaer, Acta chem. scand.
13, 442 (1959); M . J . Janssen, Recueil Trav. chim. Pays-Bas 79,
454, 1066 (1960).
[lo21 Recent determinations of the crystal structures of dithiocarbamates: K . A. Fraser and M . M . Harding, Acta crystallogr.
22, 75 (1967); R. Bally, ibid. 23, 295 (1967); G. F. Gasparri, M.
Nardelli, and A. Villa, ibid. 23, 384 (1967); C. Peyronel and A .
Pignedoli, ibid. 23, 398 (1967); M . Colapietro, A. Domenicano,
L . Scaramuzza, A. Vaciago, and L . Zambonelli, Chem. Commun.
1967, 583; M. Colapietro, A. Domenicano, L. Scaramuzza, and
A. Vaciago, ibid. 1968, 302; K . Bowman and 2. Dori, ibid. 1968,
636; A. Domenicano, L. Torelli, A . Vaciago, and L. Zambonelli,
J. chem. SOC.(London) A 1968, 1351; P . T. Beurskens, H. J. A.
Blaauw, J . A. Cras, and J. J . Steggerda, Inorg. Chem. 7 , 805
(1968); P. T. Beurskens, J . A. Cras, and J . J . Steggerda, ibid.
7, 810 (1968).
[lo31 P . Zuman and R. Zahradnik, Z . physik. Chem. (Leipzig)
208, 135 (1957); R. Zahradnik and P.Zunzan, Chem. Listy 52, 231
(1958); Collect. czechoslov. chem. Commun. 24, 1132 (1959);
B. Philipp, H . Dautzenberg, and H. Lung, Faserforsch. u. Textiltechn. 19, 325 (1968).
Angew. Chem. internat. Edit. J Val. 7 (1968) No. I 1
hence increasing basicity of the amide group), while
carboxyl or phenyl groups o n the amide nitrogen
stabilize the free acids. Apart from unsubstituted dithiocarbamic acid 11041, therefore, all the known 1 1 0 ~
chalcogenocarbamic acids are stabilized in this way,
i.r. N-(2-acetyl-2-ethoxycarbonylthioacetyl)-,N-[2,2bis(ethoxycarbonyl)thioacetyl]-, N-(2,2-diacetylthioacety1)-, and N-(2-ethoxycarbonyl-2-cyanothioacetyl)carbamic acids 11051 and N , N-diphenyl- 11061, N-cyano11071, and N-thiocarbamoyldithiocarbamic acid11081.
Dithiocarbamic acid itself is formed as colorless
needles when concentrated hydrochloric acid is added dropwise to an aqueous solution of its ammonium
salt at O°C[1041. I t is stable below O°C, but decomposes rapidly at higher temperatures to give CS2 and
ammonium dithiocarbamate r1101. The crystals melt
at about 35 "C. According to its IR spectrumI1O41,unsubstituted dithiocarbamic acid in the crystalline state
also consists of unionized acid molecules, which are
joined in pairs by strong S-H . . - N bonds. The resulting double molecules are linked to one another by
weaker S - H . . . S bonds. The decomposition of the
acid in the double molecule begins with the transfer of
the bridge proton from the sulfur to the nitrogen, the
acceptor molecule then breaking down into CS2 and
N H4'.
T h e recently described preparation of t h e liquid compounds [ I 111 N-(3-hydroxyethylcarbamic acid (perfectly stable
up to 120 "Cj a n d N,N-dimethylcarbamic acid (distils a t 60
t o 61 OC without decomposing), b o t h o f which appear t o
exist a s zwitterions, i s contrary t o all other experience with
carbamic a n d dithiocarbamic acids. Spectroscopic methods
were n o t used in t h e elucidation of t h e structures o f these
compounds.
Depending on the pH range, aqueous dithiocarbamate solutions contain S-anions, free acids in the
neutral and zwitterionic forms, or N-protonated
cations. The situation is shown in Scheme 3 [1031.
An equilibrium constant K2 o f 1.13 x lO-3[1041 has been
found for dithiocarbamic acid a t 20 " C ; for N,N-diethyldi1.6 j. 10-8 a n d K2 = 1.0 Y 10-8 (both
thiocarbamate, K1
SH
strongly acidic
free acid
alkaline
Scheme 3 .
a t 20 "Cj [ I 121. These constants have not yet been assigned t o
S- or N-dissociation.
A carbamic acid containing selenium, i.r. N,N-dimethyldiselenocarbamic acid 1981, has also been prepared. The above stability considerations based on the
tendency to form a zwitterion with equivalent carbonchalcogen bonds do not apply to this acid. A similar
conclusion is indicated by the results of a crystal
structure determination on nickel bis(N,N-diethyldiselenocarbamate) [1131, according to which there are
two different C-Se distances in N,N-diselenocarbamate (C-Se = 1.84 and 1.97 Ar1141). The C-S
distances in the corresponding dithio compound are
approximately equal (1.68 and 1.70 A) 11151.
5.2. Chalcogenocarbazic Acids
Hydrazinium salts of the chalcogenocarbazic acids
are formed on reaction of hydrazine with C02rl161,
COS 11171, CS2 IllSI, CSSe 11191, or CSe2 [118,1201. In
addition to the hydrazinium salts, a number of tran1211.
sition metal complexes are also known
The free carbazic acids are found only as $-protonated zwitterions, owing to the strong basicity of
their $ nitrogen. This strongly hinders the a-protonation required to initiate the decomposition. At the
same time there is a substantial gain in lattice energy
7
~~~
~~~
[lo41 G . Gattow and V. Hahnkamm, Angew. Chem. 78, 334
(1966);Angew. Chem. internat. Edit. 5,316 (1966);Z.anorg. allg.
Chem., in press.
[lo51 T . N. Ghosh and A C. Guha, J. Indian Inst. SCI.,A 16, 103
(1933).
[lo61 D. Craig, A. E. Juve, W . L. Davidson, W. L. Semon, and D.
C . Hay, J . Polymer Sci. 8, 321 (1952)
[lo71 A. Hantzsch and M . Wolvekamp, Liebigs Ann. Chem. 331,
265 (1904); F. B. Johnson, A. J. Hill, and B. H . Bailey, J. Amer.
chem. Sac. 37, 2406 (1915). For the complexing tendency and
preparative use of the anion of N-cyanodithiocarbamic acid,
Cf. (191;F. A . Cotton and J . A. McCleverty, Inorg. Chem. 6,229
(1967); R. J. Timmons and L. S . Wittenbrook, J . org. Chemistry
32, 1566 (1967); J. J . DAmico and R. H . Campbell, ibid. 32,
2567 (1967);K . A . Jensen and L. Henriksen, Acta chem. scand.
22, 1107 (1968);F. A. Cotton and C.B. Harris, Inorg. Chem. 7 ,
2140 (1968). S-addition leads to dimercapto-l,2,4-thiadiazole:
E. Siiderback, Acta chem. scand. 17,362 (1963).
[I081 Trithioallophanic acid: [107]; A . Rosenheim, R . Levy, and
H . Grunbaum, Ber. dtsch. chem. Ges. 42, 2923 (1909).
[I091 LCAO-MO calculation for a free carbamic acid: E. L.
Wagner, J. physic. Chem. 63, 1404 (1959).
[I 101 Regarding the polymorphic nature of ammonium dithiocarbamate, cf. V. Hahnkamm, G. Kiel, and G . Gattow, Naturwissenschaften 55, 80 (1968).
[I111 P. F. Pascoe, Liebigs Ann. Chem. 705, 109 (1967);708, 72
(1967).
Angew. Chem. internat. Edit. J VoL 7 (1968)
' No.
If
[112] K. P. Soni and A. M . Trivedi, J. Indian chem. SOC.37, 349
(1960); K . P. Soni, A. M . Trivedi, and I. M . Bhatt, ibid. 43, 85
(1966).
[113]M . Bonamico and G. Dessy, Chem. Commun. 1967, 1114.
11141 C-Se = 1.82 11 in N-benzoyl-N'-phenylselenourea [37].
11151 M . Bonamico, G . Dessy, C . Marian;, A . Vaciago, and L.
Zambonelli, Acta crystallogr. 19, 619 (1965).
11161 R . Stolle and K . Hofmann, Ber. dtsch. chem. Ges. 37, 4523
(1904);F. Ephraim and E. Lasocki, ibid. 44, 395 (1911).
[117]K. A. Jensen, Z . anorg. allg. Chem. 221, 15 (1934); E.
Nachbaur and W. Goftardi, Mh. Chem. 95, 779 (1964).
[118a] U. Anthoni, Acta chem. scand. 20, 2742 (1966).
[118b] U. Anthoni, C . Larsen, and P . Nielsen, Acta chem. scand.
21, 2571, 2580 (1967).
[119] H . V. A. Briscoe, J. B. Peel, and P. L . Robinson, J. chem.
SOC.(London) 1929, 56.
[120] F. Feller, D. Hirschfeld, and K.-H. Linke, Z . Naturforsch.
176, 625 (1962).
[121]Transition metal complexes of carbazic acid: A .
Braibanti, G. Bigliardi and R . Canal; Padavani, Gazz. chim. ital.
95, 877 (1965); A. Braibanti, G . Bigliardi, A . M . Manotti Lanfiedi, and A. Tiripicchio, Nature (London) 211, 1174 (1966);
J . Slivnik, A . Rihar, and B. Sedej, Mh. Chem. 98, 200 (1967).
Crystal structure determinations: A . Ferrari, A. Braibanti, G .
Bigliardi and A . M . Manotti Lanfredi, 2. Kristallogr. 122, 259
(1965); A. Braibanti, A. M . Manotti Lanfredi, and A . Tiripicchio,
ibid. 124, 335 (1967).
875
in the crystalline state. The carbazic acids are
consequently much more stable than corresponding
carbamic acids. The zwitterionic character has been conclusively demonstrated by IR spectroscopy L1181.
Carbazic acid is formed as a white powder by way of a
hydrazinium salt L1221 when COl is passed into hydrazine for several days 11161. Dithiocarbazic acids
(N, N-dimethyl-, N, N-diethyl-, N, N-diisopropyl-, N, Npentamethylene- *I, and N-phenyldithiocarbazic acids)
and diselenocarbazic acids (N,N-dimethyl- and Nphenyldiselenocarbazic acids) are formed as white or
orange-red crystals on dropwise addition of aqueous
solutions of their salts to an equimolar quantity of
6 N hydrochloric acid r118al. N, N-Diisopropylthioselenocarbazic acid is formed by reaction of N-isothiocyanatodiisopropylamine with H2Se ; an analogous reaction with H2Te yielded only ditelluride [118bl
5.3. Chalcogenoisocyanic Acids
Anions of chalcogenoisocyanic acids are formed by
addition of 0, S, Se, or Te to cyaniderll. Salts of
OCN-, SCN-, and SeCN- 11231 have been known for
a long time; TeCN-, on the other hand, has only been
detected in small concentrations in aqueous solution
by its U V spectrumrl~41, whereas all attempts to
prepare it as such have so far been unsuccessful [1251.
T h e simple linear shape of the chalcogenocyanates, their
interesting formation conditions, a n d their pronounced
tendency t o form complexes have led to numerous investigations o n their vibration [I261 and electronic excitation spec[122] The compound is reported to be distillable [116]. N o
structural investigations have been reported.
[*I Correct name: N-piperidinodithiocarbamicacid.
[123] Review o n selenocyanates: A . M. Golub and V . V. Skopenko, Usp. Chim. 34, 2098 (1965).
[124] E. Gusarski and A . Treinin, J. physic. Chem. 69, 3176
(1965); M . A. Bennett, R. J. H . Clark, and A. D . J . Goodwin, Inorg. Chem. 6, 1625 (1967); H.-H. Schmidtke, Ber. Bunsenges.
physik. Chem. 71, 1138 (1967).
[125] Review of attempted preparations: 0. Foss, Acta chem.
scand. 4 , 1241 (1950); N. N. Greenwood, R. Little, and M . J .
Sprague, J. chem. SOC.(London) 1964, 1292.
(1261 P. C. H. Mitchell and R. J . P. Williams, J. chem. SOC.
(London) 1960, 1912 (data from the earlier literature o n the I R
spectra and crystal structure determinations); Y . Y. Kharitonov,
G. V. Tsintsadze, and M. A . Porai-Koshits, Doklady Akad. Nauk.
SSSR 160, 1351 (1965); 2. neorg. Chim. 10, 792 (1965); A . Sabatin; and I. Bertini, Inorg. Chem. 4 , 959 (1965); D. Forster and
D. M. L. Goodgame, ibid. 4, 715 (1965); J . L . Burmeister and L. E.
Williams, ibid. 5 , 1113 (1966); R. J. H . Clark and C . S. Williams,
Spectrochim. Acta 22, 1081 (1966); M. Nardelli, G. F. Gasparri,
G. G. Batfistini, and P. Domiano, Acta crystallogr. 20, 349 (1966);
M . Nardelli, G. F. Gasparri, A. Musatti, and A . Manfredotti,
ibid. 20, 910 (1966); D. Forster and W . de W. Horrocks, jr., Inorg.
Chem. 6 , 339 (1967); D. E. Scaije, ibid. 6, 625 (1967); H.-H.
Schmidrke and D . Garthoff; Helv. chim. Acta 50, 1631 (1967);
R. Savoie and M. PPzolet, Canada J. Chem. 45, 1677 (1967);
P. C. Jain and E. C. Lingafelter, J. Amer. chem. SOC.89, 724
(1967); T. M. Brown and G. F. Knox, ibid 89, 5296 (1967); J. L.
Burmeister and H. I. Gysling, Chem. Commun. 1967, 543; Inorg. chim. Acta I , 100 (1967); J. C. Decius and D. J. Gordon, J.
chem. Physics 47, 1286 (1967); H. Bohland and P. Malitzke, Z.
anorg. allg. Chem. 350, 70 (1967); A. H. Norbury and A. I . P.
Sinha, Inorg. nuclear chem. Letters 3 , 335 (1967); I. Sotofre and
S . G. Rasmussen, Acta chem. scand. 21,2028 (1967); J . W. Jeffery,
and K. M. Rose, Acta crystallogr. B 24, 653 (1968); C. Akers,
S . W . Peterson, and R. D. Willatt, ibid. B 24, 1125 (1968); L.
Capacchi, G. F. Gasparri, M . Nardelli, and G. Pelizzi, ibid. B 24,
1199 (1968); J. R . Knox and K. Eriks, Jnorg. Chem. 7 , 84 (1968).
876
tra"241 a s well a s to crystal structure determinations [I261 and
theoretical calculations 11273 1281. T h e metal complexes can
contain X-metal o r N-metal bonds, o r even metal-XCNmetal bonds with a n XCN bridge. T h e fundamental vibration
frequencies of the anions accordingly differ widely [1261.
Of the free acids, isocyanic acid can be obtained by
pyrolysis of its trimer, cyanuric acid, at red heat 11291
or by passage of HCI gas through dry NaNCO 11301
and collection of the escaping gas at -78 "C; the acid
obtained by the second of these methods contains
less impurityr13ol. In the pure state it is a colorless
liquid that polymerizes readily (m.p. -86 OC, b.p.
23.5 "C, formation of macromolecular cyamelide
below 150°C and of trimeric cyanuric acid above
150 "C 11299, which is stable only at -78 "C and occurs in the solid state in a high-temperature and a lowtemperature modification (transition point about
-100 "C) 11311. In all aggregation states and in apolar
solvents it exists only as isocyanic acid molecules
H-N-C-0 [I31 1321. In the crystal lattice of the solid
acid, the molecules of the high-temperature modification are held together by N - H . . . N bonds, and those
of the low-temperature modification by N - H . . . O
bonds 11311. Isocyanic acid is a medium-strong acid in
aqueous solution (Ka = 3.4 x 1 0 - 4 at 25 "C) [1341.
Tsothiocyanic acid is formed as a colorless gas on
careful reaction of KSCN with KHS04[135]; it can be
condensed at -190°C to form a white solid, which
melts at -110°C and trimerizes above -90°C; extensive polymerization takes place above 0 "C [1351.
The gas phase and solutions in apolar solvents
again contain only isothiocyanic acid molecules
H-N=C=S [1361; in polar solvents, on the other hand,
an equilibrium probably occurs with the thiocyanic
[127] MO calculation for chalcogenoisocyanic acids and their
anions: E. L . Wagner, J. chem. Physics 43, 2728 (1965).
[128] Mean vibration amplitudes of chalcogenoisocyanic acids
and their anions: G. Nagarajan and T . A . Hariharan, Acta physica
austriaca 19, 349 (1965); K. Venkateswarlu, S. Mariam, and K .
Rajalakshmi, Bull. CI. Sci., Acad. roy. Belg. 51, 359 (1965); K.
Venkateswarlu and V. Malathi Devi, Proc. Indian Acad. Sci., A
61, 272 (1965).
I1291 M . Linhard, Z. anorg. allg. Chem. 236, 200 (1938).
[130] N. Groving and A. Holm, Acta chem. scand. 19, 1768
(1965).
11311 Determination of the crystal structure of the supercooled
high-temperature modification at -125 "C: W . C. von Dohlen and
G. B. Carpentor, Acta crystallogr. 8, 646 (1955).
[132] Raman spectrum, liquid: J. Goubeau, Ber. dtsch. chem.
Ges. 68, 912 (1935). Electron diffraction, gaseous: E. H . Eyster,
R. H . Gillette, and L. 0. Brockway? J. Amer. chem. SOC.62, 3236
(1940). I R spectrum, gaseous: G. Herzberg and C. Reid, Discuss.
Faraday SOC.9, 92 (1950); C. Reid, J. chem. Physics 18, 1550
(1950). I R spectrum, CHlClz solution [130]. Calculation of
force constants [133]. Mean amplitude of vibration [128].
Microwave spectrum, gaseous: L . H . Jones, J. N. Shoolery, R . G.
Shulman, and D . M . Yost, J. chem. Physics 18, 990 (1950);
K. J . White and R. L . Cook, ibid. 46, 143 (1967). Mass spectrum:
S. R. Smith and H . B. Jonassen, J. inorg. nuclear Chem. 29, 860
(1967).
11331 Force constant calculations for chalcogenoisocyanic acids:
W . J. Orville Thomas, J. chem. SOC. (London) 1952, 2383;
Trans. Faraday SOC. 49, 855 (1953); K. Venkateswarlu and
P. Thirugnanasambandam, Z. physik. Chem. (Leipzig) 218, 1
(1961).
[134] R. Caramazza, Gazz. chim. ital. 88, 308 (1958).
[135] L . Birkenbach and E . Buchner, Ber. dtsch. chem. Ges. 73,
1153 (1940).
Angew. Chem. internat. Edit.
1 Vol. 7 (1968) NO. 11
acid form N EC-S-H 11361. lsothiocyanic acid is a
strong acid in aqueous solution ( K 69 at 25 “ C )11371.
Dilute aqueous solutions of selenocyanic acid, which
rapidly decompose with separation of selenium, are
formed by the action of H2S on lead selenocyanate 11381.
N o attempt has yet been made to prepare this acid
again in nonaqueous media.
7. Chalcogenocarbonic Acids Containing Halogen
a n d Pseudohalogen
6. Chalcogenocarbonic Acids Containing
Phosphorus
The phosphinochalcogenoformic acids H2P-CXXH,
which would correspond to the chalcogenocarbamic
acids, have not yet been prepared. Metal complexes
of P,P-diphenylphosphinomonothioformic and -dithioformic acids are formed on reaction of phenyldiphenylphosphinozincr1391, triphenyldiphenylphosphinotin ‘1401, and teti akis(dipheny1phosphino)tin ‘1401
with CS2 o r COS. According t o their I R spectrum
these last complexes contain covalent Sn-S and
Sn--O bonds 11401.
When CS2 or CSe2 is brought into contact with tertiary
phosphines, zwitterions of the phosphinoformic acids
are formed [1411. Corresponding carbamic acids are
unknown.
The betaines are much more stable than the rapidly decomposing zwitterions of the N,N-dialkylcarbamic
acids, but react as a mixture of tertiary phosphine and
CS2 1141 1421. Their structure has been confirmed by IR
spectroscopic studies 1141 1431 and a crystal structure
determination 11441 on the triethylphosphine-CS2
compound (“triethylscarphan”).
[136] Raman spectrum in cc14 and ether: J . Goubenu and D.
Gott, Ber. dtsch. chem. Ges. 73, 127 (1940). 1R spectrum, gaseous
and solid: C. Reid, J. chem. Physics 18, 1512 (1950); J. R. Durig
and D. W . Wertz, ibid. 46, 3069 (1967). Calculation of force
constants [133]. Mean amplitude of vibration [128]. Calculation
of thermodynamic functions: H . Mackle and P. A . G. O’Hare,
Trans. Faraday SOC.60, 666 (1964). Microwave spectrum in the
gas phase: C. I . Beard and B. P. Doiley. J. chem. Physics 18, 1435
(1950); 19, 975 (1951); G. C. Dousmanrs, T. M . Sanders, C . H .
Townes, and H . J. Zeiger, ibid. 21, 1416 (1953); R . Kewley,
K . V. L . N . Snstry, and M . Winnewisser, J. molecular Spectroscopy 10, 418 (1963).
[137] T. D. B. Morgan, G. Stedmann, and P. A. E. Whincup, J.
chem. SOC.(London) 1965, 4813; S. Tribalat and J. M . Caldero,
Bull. SOC.chim. France 1966, 774, give K, = 5.
[138] H . P . Kaufmann and F. Kugler, Ber. dtsch. chem. Ges. 59,
178 (1926).
[139] J . G. Noltes, Recueil Trav. chim. Pays-Bas 84,782 (1965).
11401 H. Schumann, P. Jutzi, and M . Schmidt, Angew. Chem. 77,
812 (1965); Angew. Chem. internat. Edit. 4 , 787 (1965).
El41 1 K. A . Jensen and P . H . Nielsen, Acta chem. scand. 17, 547,
549 (1963).
[1421 C. Screttas and A. F. Isbell, J. org. Chemistry 27, 2573
(1962).
[143] M . Arshad, A . Beg, and M. S . Siddiqui, Canad. J. Chem.
43, 608 (1 965).
[144] T. N. Margulisand D. H . J. Templeton, J. Amer. chem. SOC.
83, 995 (1961); J. chem. Physics 36, 231 1 (1962).
Angew. Chem. internat. Edit.
/ Vo1. 7 (1968) / No.
CS2 reacts with Pt(0)- or Pd(0)-triphenylphosphines t o give
addition compounds having t h e formulas P ~ I P ( C ~ H ~ ) ~ ] . C S Z
a n d P ~ [ P ( C G H ~ ) ~ ] . CThese
S ~ . compounds d o not contain C--P bonds; o n t h e contrary, an angular CS2 molecule
(1 36 and 139.7 ”) is bound t o Pt or Pd by C and an S a t o m 11451.
Similar complexes with CS2 and COS a r e k n o w n for other
transition metals 11451.
I1
Halogen derivatives of the chalcogenocarbonic acids
YCXXH (where X .= chalcogen, Y - halogen) are
named as halogenoformic acids. Only the esters are
known so far as stable solid compounds. Free chloroformic acid [67J is formed in the photochemical reaction of Cl2-formic acid mixtures as a short-lived intermediate having a half-life of 50 to 70 psecIl461; it has
been detected by means of its C-CI absorption at
768 cm-1 with a fast-recording instrument in a mixture
ignited by flash photolysis. Chloroformic acid decomposes into COz and HCI. Chlorothioformic acid
is reported to be formed on careful hydrolysis of
thiophosgene 11471. Halogenoformic acids are also
postulated as active substances in the corrosion of
metals by halogens 11481.
On the other hand, cyanodithioformic acid, which
contains the pseudohalogen CN, and which precipitates out as a colorless solid on dropwise addition of
hydrochloric acid to a nonaqueous solution of one of
its salts, is surprisingly stable 11491. Its salts are formed
on reaction of CS2 with cyanides in dimethylformamide 1149-1511. The sodium salt changes readily into
the disodium salt of dimercaptomaleonitrile~~49.15o~.
Salts of cyanodiselenoformic acid are formed in a
vigorous reaction of CSe2 with cyanide, again in dimethylformamide 11491.
-.- .- . -
[145] M . C. Bairdand G . Wilkinson, Chem. Commun. 1966, 514;
J . chem. SOC. (London) A 1967,865; M. C . Baird, G. Hartwell, ir..
R . Mason, A . I. M. Roe, and G. Wilkinson, Chem. Commun.
1967, 93; T. Kashiwagi, N . Yasuoka, T . Ueki, N . Kasai, and M .
Kakudo, Bull. chem. SOC.Japan 40, 1998 (1967); J . D. Gilbert,
M . C. Baird, and G . Wilkinson, J. chem. SOC.(London) A 1968,
2198. Binuclear complexes with CS2-bridges: M . C. Baird, G .
Hartwell, j r . , and G . Wilkinson, J. chem. SOC. (London) A
1967, 2037; T . Mizuta, T. Suzuki, and T . Kwan, J. chem.
SOC.Japan, pure Chem. Sect. (Nippon Kagaku Zasshi) 88, 573
(1967).
[146] H . L . West and G. K . Rollefson, J. Amer. chem. SOC.58,
2142 (1936); G. C. Pimentel and K . C. Herr, J. Chim. physique
Physico-Chim. biol. 61, 1509 (1964); K . C. Herr and G. C. Pimentel, Appl. Optics 4 , 25 (1965); R . J . Jensen and G. C. Pimentel,
J. physic. Chem. 71, 1803 (1967).
[147] H . Bohme, Ber. dtsch. chem. Ges. B 74, 248 (1941).
[148] E. Rabald, Werkstoffe and Korrosion 12, 695 (1961).
Dechema Monogr. 45, 105 (1962). Cf. also the formation of 1 : 1
molecular complexes of COZ o r COS with HCI and HF: T . G.
Burke and D. F. Smith, J. molecular Spectra 3, 381 (1959).
[149] G. Bahr and G. Schleitzer, Chem. Ber. 88, 1171 (1955); 90,
438 (1957).
[150] H . E. Simmons, D. C. Blomstrom, and R . D. Vest, J . Amer.
chem. SOC.84,4756 (1962).
[I511 H . Hahn, G. Mohr, and A. v . Schoor, German Pat. 1 158056
(Nov. 28, 1963), Merck.
877
8. Chalcogenocarbonic Acids in the Ortho Form
Very stable tetraalkyl esters of chalcogenocarbonic
acids with four chalcogen atoms directly bonded to
the C atom can be preparedlll. On the other hand,
neither the free acids nor any of their salts can be obtained as such, or even detected indirectly, though
ortho compounds of this type are frequently postulated
as intermediates in the hydration of carbon dioxide [I521
and in the formation and decomposition of trithiocarbonate 12,1531,xanthate [2,3.1541,and carbamater1551.
Though plausibility considerations are very convincing,
particularly in the xanthate reactions [31, there is still
absolutely no proof of the occurrence of such intermediates.
The same is true of the silver salts that are reported to
be formed from xanthate and AgN03 121 and of a nickel
orthocarbonaterl561 whose occurrence has been
postulated in the thermogravimetric degradation of
basic nickel carbonates.
9. Perchalcogenocarbonic Acids
In this context the term “perchalcogenocarbonic
acids” will be taken to mean compounds that contain
the grouping X-X instead of a single chalcogen atom X.
9.1. Peroxocarbonic Acid and Peroxocarbonates
I1571
Peroxocarbonates can be obtained by three methods:
1. Anodic oxidation of concentrated carbonate solutions ‘1581;
2. Action of C 0 2 on peroxides or hydrogen peroxides 11591;
3. Reaction of carbonate or ethyl carbonate with
H202 [1601.
[152] E. Wilke, Z . anorg. allg. Chem. 119, 365 (1921); A. Thiel,
ibid. 121, 211 (1922); J. Koefoedand K . Engel, Acta chem. scand.
15, 1319 (1961).
11531 H . Schreiber, Arch. Pharmaz. 64, 89 (1959).
[154] P . Herrent and G . Inoff, J. Polymer Sci. 3, 487, 834 (1948);
5, 727 (1950); E. Treiber, G . Porod, and W. Lung, Osterr. Chemiker-Ztg. 53, 162 (1952).
[155] P. F. Pascoe, Liehigs Ann. Chem. 705, 118,125,134(1967).
[156] 2. Srmal, Wiadom6sci chem. 8, 241 (1954).
[157] For a review of the peroxocarbonates, see J . R. Partington
and A . H . Fathallah, J. chem. SOC. (London) 1950, 1934; M.
Gutierrez de Celis and J. R. Masaguer, An. Real SOC.espafi.
Fisica Quim., Ser. B 51, 693 (1955).
[158] I. F. Franchuk and A . I. Brodskii, Doklady Akad. Nauk.
SSSR 118, 128 (1958); A . I . Brodskii, I. P. Gragerov, I. F. Franchuk, L . V. Sulima, I. I. Kukhtenko, V. A . Lunenok, A. S. Fomenko, and M . M . Aleksankin, Trans. Tashkent Conf. on the
Peaceful Use of Atomic Energy, Acad. Sci. Uzbek. SSR 2, 327
(1960); Chem. Abstr. 57, 9258e (1962); N . E. Khomutov, M . F.
Sorokina, and L . S. Filatova, Chim. Perekisnykh. Soedin., Akad.
Nauk. SSSR, Inst. obshch. i neorgan. Chim. 1963, 140; N . E.
Khomutov and M . F. Sorokina, 2. fiz. Chim. 40, 44 (1966).
11591 A. K . Melnikow and T. P. Firsova, 2. neorg. Chim. 6,2230,
2470 (1961).
[160] J. R. Masaguer, An. Real SOC.espati. Fisica Quim., Ser. B;
52, 325 (1956); A . Leko and W . Rekalitscha, Docum. Chem.
Yugosl. 22, 193 (1957); N . Kolarow and M . Manewa, Z . anorg.
allg. Chem. 319, 196 (1962).
878
Only the products obtained by methods 7 and 2 are
true peroxocarbonates with C - 0 - 0 bonds. The
third reaction yields carbonates containing HzO2
of crystallization 11611.
T h e composition of the peroxocarbonates varies widely with
t h e preparation conditions, a n d whereas extensive studies
have provided considerable information o n t h e kinetics o f
their anodic formation “581, nothing definite is yet known
about t h e structure o f individual peroxocarbonates. Suggestions [I571 include t h e formulas of a simple peroxocarbonate
COi-, a dimer 11621,
a n d a hydrogen peroxocarbonate HCO:.
Free peroxocarbonic acid is reported t o b e formed o n reaction of peroxocarbonates with phosphoric acid as a substance that can be extracted with ether “631, as well as from
COz and H202 in aqueous solution 11641 a n d o n irradiation o f
water containing COz with X rays “651. These data a r e based
more on assumptions t h a n o n accurate identification o f t h e
acid formed, a n d have in some cases been definitely refuted [163,1641. O n t h e other hand, polarographic studies have
shown t h a t t h e hydrolytic decomposition of peroxocarbonates in aqueous solution proceeds via a free acid [1661.
9.2. Perthiocarbonic Acid and Perthiocarbonates
Solutions of the supposed trithioperoxocarbonate ion
CS3O2- are formed when dilute aqueous trithiocarbonate solutions are left in air for several days [2,1671.
The solutions give UV absorptions at 308 and 378 nm,
whereas the absorption bands of the CS:- ion have
completely disappeared. Solutions exhibiting the
same UV absorption are also formed on saturation
of dilute hydrogen sulfide solutions with COS and
0 2 [21.
The tetrathiocarbonate ion CSi- (referred to as perthiocarbonate in the following discussion) is formed
on reaction of disulfides with CS2 in alcohol; crystalline or initially oily salts can be precipitated with
etherr7,491. Solutions of CSi- are also formed on
treatment of trithiocarbonate solutions with sulfur 12,1681. The known salts include alkali metal salts,
[161] T. M. Connor and R . E. Richards, J. chem. SOC.(London)
1958, 289; A . Prokopcikas and A. Vaskelis, Trudy Akad. Nauk
Litovskoi SSR, Ser. B 1963, 61; A . Vaskelis and A . Prokopcikas,
ibid. 1963, 75; A . Prokopcikas and A . Vaskelis, Chim. Perekisnykh. Soedin., Akad. Nauk. SSSR, Inst. obshch. i neorgan.
Chim. 1963, 150; C. Rocchiccioli, C. R. hebd. SSances Acad. Sci.
261, 361 (1965); I . F. Franchuk, Teoret. eksper. Chim., Akad.
Nauk. Ukr. SSR I , 531 (1965).
11621 G. S. Karetnikov and M . F. Sorokina, Z . fiz. Chim. 39, 364
(1965).
[163] A . Bach, J. russ. physik.-chem. Ges. 29, 373 (1897); R .
Wolffenstein and E. Peltner, Ber. dtsch. chem. Ges. 41, 280 (1908).
[164] P . van Rysselberghe, P. Delahay, A . H . Gropp, J. M. McGee.
and R . D. Williams, J. physic. Colloid Chem. 54, 754 (1950);
I. Sekerka and J. VorliEek, Chem. Listy 48, 920 (1954).
[165] K . Schmidt, Nature (London) 187, 931 (1960).
[166] A. Vaskelis and A . Prokopcikas. Trudy Akad. Nauk Litovskoi SSR, Ser. B 1963, 75.
[167] S. G . Hovenkamp, J. Polymer Sci., Part C 2, 341 (1963).
[168] G. Gattow and B. Krebs, Z . anorg. allg. Chem. 323, 260
(1963); concerning the reaction mechanism, cf. [lo71 and E.
Sfiderbuck, Acta chem. scand. 19, 549 (1965).
Angew. Chem. internat. Edit.
1 Vol. 7 (1968) 1 No. I I
in some cases with widely differing contents of water
of crystallization 11691, calcium salts having widely
varying compositions [1701, and a few transition metal
complexes '20,1711.
Analysis of the vibration spectrum of the CSi- ion
shows that it has a true perthiocarbonate structure 1172J.
An elementary HMO calculation gave the x-electron
densities and x-bond orders shown in Scheme 411721.
S 1.775
s.sp
0.569 C 0 . 8 2 8
1.978
1.724
H2CS4 thus has the unsymmetrical structure
HS-C(S) - S - S-H. This structure explains why
H2CS4 cannot be obtained from H2CS3 and sulfurIl681, whereas its anion can be obtained by reactions of this type. The thermodynamic data obtained
by vapor pressure measurements over the decomposing acid 1491, in conjunction with the corresponding data for trithiocarbonic acid [511, show that the
formation of the perthio acid from H2CS3 and S would
be thermodynamically possible above 57 "C. However, neither H2CS4 nor H2CS3 is stable at this
temperature. Dissociation constants of perthiocarbonic acid in aqueous solution are given in Table 4.
\
0,557
9.3. Peroxocarbonates Containing Selenium
S 1.735
Scheme 4.
Free perthiocarbonic acid H2CS4 is formed on reaction of equimolar quantities of ammonium perthiocarbonate and HCI gas in dimethyl ether at -78 "C 1491;
filtration of the solution and evaporation of the dimethyl ether at -78°C under vacuum yields H2CS4
as a yellow crystalline substance melting at -36.5 "C
to give a red oil, which rapidly becomes cloudy owing
to the separation of sulfur. The acid is stable at
- 190 "C; at --78 "C, it decomposes slowly into H2S,
CS2, and sulfur.The IR spectrum of HzCS4 in C C 4 contains two S-H stretching bands at 2575 and 2395 cm-1;
[169] P . Silber and S. Pelloux, C . R. hebd. Seances Acad. Sci. ( C )
262, 1006 (1966).
[170] J . G. O'Donoghue and Z . Kahan, J. chem. SOC.(London) 89,
1812 (1906).
[171] G . Peyronel, D . de Filippo, and C. Preti, Ric. sci., Parte 11,
Sez. A 6, 391 (1964); D. de Filippo, C. Preti, G. Peyronel, and G .
Marcotrigiano, ibid. 6, 41 1, 429 (1964).
[172] A . MiiNer and B. Krebs, Z. anorg. allg. Chem. 347, 261
(1966).
CSe:- solutions do not react with selenium L171. Concentrated aqueous Na2CS3 solutions take up 0.6 gatom of selenium per mole of CSt-, but there is no
evidence of compound formation corresponding to
the formation of CSi- from CSi- and sulfur; Na2CS3
and selenium are precipitated separately on addition
of alcohol and etherll731.
On the other hand, when a suspension of sulfur in an
aqueous BaCSzSe solution is vigorously stirred, the
U V bands of the CS2Se2- ion (325, 365, and 535 nm)
disappear, to be replaced by a spectrum containing
absorption bands at 319 and 397nm, which (apart
from a small shift toward longer wavelengths) is of
the same form as the spectrum of the CSa- ion [231. It
may therefore be assumed that an ion oSe-C(S)-S-S cT
is formed.
Received. December 18, 1967
[A 668 IEI
German version. Angew. Chem. 80, 954 (1968)
Translated by Express Translation Service, London
[173] G. Gattow and B. Krebs, unpublished.
COMMUNICATIONS
Bimetallic 7r-Ally1 Complexes of Nickel and
Palladium
By W. Keim[*l
Dedicated t o Professor K . Ziegler on the occasion of his
70th birthday
If, in accord with the method of G . Wilke et al.[ll for the
preparation of x-allylnickel halides, bis(l,5-cyclooctadiene)nickel is treated with ( I ) 121 in toluene for 24 h at 0 "C, the
complex 2,2'-bis(x-allyl)dichloronickelpalladium (2) is formed in 70-80% yield. The precipitation of metallic nickel
during the reaction suppresses the formation of (2).
\w+-Cl
c1
(1)
+
(COD)2Ni + C l - N < M d - C I
+ 2 COD
(2)
The brown insoluble compound (2) reacts with cyclopentadienylsodiurn, forming 2,2'-bis(~c-allyl)dicyclopentadienylnickelpalladium (3). which is readily soluble in organic
Angew. Chem. internet. Edit.
/ Vol. 7 (1968) J No. I I
solvents, sublimes at 90 O C / l O - 4 torr, and forms red needles
that decompose at 150-160 ' C . Hydrogenation of ( 3 )
affords metallic nickel and palladium, 2,3-dimethylbutane,
and cyclopentane. Its mass spectrum131 is in accord with
structure (3). The 1H-NMR spectrum shows six sharp
signals (see Table 1).
Table 1. 'H-NMR spectral bands of (3) and (41 in CaD6 at
(Internal reference tetramethylsilane; Varian A 60).
30°C
i41
Proton
Ha
"b
Hc
Hd
He
Hf
-
(ppm)
1.15
2.75
3.65
2.15
5.75
5.15
2
2
1.3
3.05
2
2
5
-
5
5.30
I relative intensity
2
2
~
-
5
879
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