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New Products of Reaction of Organometallic Compounds with Sulfur Selenium Tellurium and Phosphorus.

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ANGEWANDTE CHEMIE
V O L U M E 4 - N U M B E R 12
DECEMBER 1965
P A G E S 1 0 0 7 - 1 102
New Products of Reaction of Organometallic Compounds with Sulfur,
Selenium, Tellurium, and Phosphorus
BY DR. HERBERT SCHUMANN AND PROF. DR. MAX. SCHMIDT
INSTITUT FUR ANORGANISCHE CHEMIE DER UNIVERSITAT W R Z B U R G (GERMANY)
Bond fission of molecular sulfur, selenium, and tellurium by lithiotriphenylmetal compounds
(of Ge, Sn, Pb) is summarized. The products are suitable as starting materials for synthesis
of new “ether analogues”. Transphenylation with tetraphenylstannane is interpreted as a
high-temperature variant of the usual fission of chalcogen molecules by nucleophilic reagents.
In principle, transphenylation can be applied also to other elements, as is illustrated for
phosphorus. In the syntheses achieved, many of the tin-phosphorus compounds arising as
intermediates can be isolated.
I. Introduction
The strikingly easy fission, by nucleophilic reagents, of
sulfur-sulfur bonds in compounds (“modifications”) of
sulfur with itself and in sulfane chains has been ascribed
by us to a marked tendency of the sulfur atom to
expand its octet, thereby forming multiple bonds between sulfur atoms. The stability and behavior of such
sulfur-sulfur bonds, and the appearance of favored
electrophilic centers in sulfur chains, are readily interpreted in terms of this assumption of a delocalized
electron system 111. This hypothesis provides a simple
explanation of the formation of fission products of
sulfur (S), by nucleophilic reagents such as SO3H-,
SH-, SR-, CN-, RC-C-, NO;, HASO:-, NR;, etc.
Such fission reactions of S-S bonds have not only
analytical but also considerable preparative importance;
they can be rationally extended to the sulfur homologues
selenium and tellurium.
simple preparative route to the little investigated field
of organometallic derivatives (with germanium, tin, or
lead) of chalcogens.
II. Chalcogen Fission by Lithiotriphenyl-germane,
-stannane, and -plumbane
The formation of formal analogues of triphenylmethyllithium by replacement of the tertiary carbon atom by
Ge, Sn, or Pb is illustrated by the well-known lithiotriphenylstannane [2-19J. This is best prepared by treat-
.
[I] M . Schmidt, Osterr. Chemiker-Ztg. 64, 236 (1963).
[2] C . A . Kraus and W . V . Session, J. Amer. chem. Soc. 47,2361
(1925).
[3] R . F. Chambers and P. C . Scherrer, J . Amer. chem. SOC.48,
1054 (1926).
[4] C. A . Kraus and S. L. Forster, J. Amer. chem. Soc. 49, 457
(1927).
[5] C. A. Krausand W . H . Kahler, J . Amer. chem. Soc. 55, 3531
(1933).
[6] H. Gilman and R. V. Joung, J. org. Chemistry I, 315 (1963).
[7] G. Wittig, R . Mangold, and G. Felletschin, Liebigs Ann.
Chem. 560, 116 (1940).
[8] G. Wittig and F. J. Meyer, Liebigs Ann. Chem. 571, 167
(1951).
[9] H. Gilman and S. D . Rosenberg, J. Amer. chem. Soc. 74, 531
(1952).
[lo] H, Gilman, L. Summes, and R. W . Leeper, J. org. Chemistry
17, 630 (1952).
[ l l ] H. Gilman and E. Bindschadler, J. org. Chemistry 18, 1675
(1953).
1121 H. Gilman and C. A. Gerow, J. Amer. chern. Soc. 77,5509,
5740 (1955).
1 No. 12
1007
Among the particularly good “thiophilic” reagents are
carbanions such as occur in organolithium and Grignard compounds. Molecular sulfur reacts spontaneously with these carbanions, yielding mercaptides or
thiophenoxides. We asked ourselves whether analogous
reactions could be carried out with compounds that are
formally derived from organometallic compounds in
that the metalated carbon atom is replaced by germanium, tin, or lead. The expected covalent chaicogen compounds should be very reactive and should open a
Angew. Chem. internat. Edit.
Yol. 4 (1965)
iiig chlorotripheiiylstannanewith an excess of lithium in
tetrahydrofuran 11% 191; the primary product, formed
according to Eq. (a), is hexaphenyldistannane, which is
then more slowly cleaved according to Eq. (b).
Germanium [201 and lead compounds [211 can be similarly
obtained. These reactive "metal organyls" R3MLi have
not yet been isolated in pure free form. However, their
solutions in tetrahydrofuran can be readily obtained on
removal of lithium chloride and the excess of lithium
under dry nitrogen. Even under mild conditions the
compounds R3MLi (M = Ge, Sn, or Pb) react exactly
like carbanions with sulfur, selenium, and tellurium in
tetrahydrofuran, moisture being excluded. This reaction [see Scheme (c)] can be illustrated for tin/sulfur.
The bonding in the s!3 ring is symbolized as in structures
( l a ) and (Ib). One of the electronically equivaIent but
still electrophilic sulfur atoms in the s8 ring is attacked
by, c'.g., the nucleophilic SnR3e anion (R = C&),
whereby ring cleavage leads to the octasulfane derivative (2). This unsyinmetrical anion (2) is then degraded
etc.
R3Sn'S'S@
-+ R3SnS@ + R,SnS@
t
+ %nR3
Sa
+
8 LiSnR3
+
8 Li-S-SnI13
stepwise by an SN2 mechanism: the ion SnR30, acting
as nucleophile, attacks the electrophilic center, namely
the terminal S atom with its formal octet [the negative
charge is equally distributed ocer the R3Sn-(S),chain], and ejects the weaker nucleophilic group
R3SnS,-1 e. In each cleavage step, down to x = I , a new
(terminal) electrophilic center is created. The &st step
- ring-opening - is rate-determining since it involves
a formal electron decet; the further steps involve formal
octets.
Selenium and tellurium react in principle like sulfur.
Thus, solutions of R3MXLi (R = C6H5; M = Ge, Sn, or
Pb; X = S, Se, or Te) [19~21-241 in tetrahydrofuran can be
obtained fairly easily. As expected, compounds R3MXLi
are sensitive to solvolysis, oxidation, and elevated
temperature (condensation: 2R3MSLi + R3M-S-MR3
+ Li2S) and thus can be isolated only with difficulty, if
at all. U p to the present, only triphenyltin-lithium sulfide
has been actually isolated c19l; it forms colorless crystals
and is dimeric in benzene, probably forming a fourmembered ring (3). Isolation is not necessary if the
compounds R3MXLi are to be used for syntheses that
can be carried out in tetrahydrofuran (see Section i l l ) .
I
Li
It has not yet been possible to synthesize trimethylgermanyl-lithium chalcogenides corresponding to t butyl mercaptides by the above procedure because the
lithiotrimethylgermane, (CH&GeLi, needed as starting
material is not yet available. Ruidiscli 1251 prepared ti-imethylgermanyl-lithium chalcogenides in a different
way: dichlorodimethylgermane and triethy Iammonium
sulfide in benzene solution afford the cyclic, trimeric dimethylgermanium sulfide; the corresponding selenide, [(CH3)2GeSe]3 (4), is formed from sodium
selenide 1261. These cyclic inorganic compounds are
smoothly and quantitatively cleaved by methyl-lithium,
yielding the desired "mercaptides" according to reaction (d).
H3C;Ce/Se\GeLH3
H:C
I
Se,
1131 H . Gilman, D. J . Peterson, and D. Wittenberg, Chem. and
Ind. 1479 (1958).
[I41 H. Gilmnn and D. Wittenberg, J. org. Chemistry 23, 1063
(1 958).
[I51 H . Gilmnit and G. D.Lichtenwalter, J. Amer. chem. SOC.80,
608 (1958).
[I61 C. Tamborski, F. E. Ford, and W. L. Lehn, J. org. Chemistry
27, 619 (1962).
1171 H . Gilinan, 0. L . Morrs, and S . J. Sim, J. org. Chemistry 27,
4232 (1962).
[ 181 H . Schuniann, K . F. Thorn, and M . Schmidt, Angew. Chem.
75, 138 (19631; Angew. Chem. internat. Edit. 2, 99 (1963).
1191 H. Schumann, K . F. Thoin, and M . Schmidt, J. organornet.
Chemistry I , 167 (1963).
[20] M. C. Henry and W . E. Davirlson, J. org. Chemistry 27, 2252
(1962).
[21] M . C. Henry and A. W. Krebs, J. org. Chemistry 28, 225
(1963).
1008
I
+
'cH3
,Se
H3CNGe\CH3
3 LiCH3
-
3 Li-Se-Ge(CHs),
(4)
(CH3)3GeSLi[251 (decornp. M 85 "C) a n d (CH&GeSeLi 1271
(decomp. M 65OC) can b e obtained as colorless solids.
(C6H&SnC12
reacts with lithium, in principle like
-
(22) H. Schumann, K . F. Thorn, and M . Schmidt, J. organomet.
Chemistry 4, 22 (1965).
(231 H. Schumann, K. F. Thorn, and M . Schmidt, J. organomet.
Chemistry 2, 361 (1964).
[241 H. Schuinann, K . F. Thoni, and M Schniidt, J. organomet.
Chemistry 4, 28 (1965).
[25] I. Ruidisch and M . Schmidt, Chem. Ber. 96, 1424 (1963).
[26] M . Schmidt and H. Ruf, J. inorg. nuclear Chem. 25, 557
(1963).
[27] I. Ruidisch and M. Schmidt, J. organomet. Chemistry 1, 160
(1963).
Angew. Chem. internnt. Edit.1 VoG. 4 (1965) No. 12
(C6H5)3SnCIr yielding (C6H&SnLi2 (not isolated), which
with sulfur affords the unusually sensitive and reactive
(C6H&Sn(SLi)2 [2*'.
Table 1. "Ether analogues" prepared by double decompositiou
according to reaction (e).
Compound
M.p. [ "Cl
138
137
I29
144
138
I40
III. Condensation of Chalcogen Cleavage Products
with Organylmetal Halides
As expected, the organylmetal chalcogenides described
above (which, however, were not all isolated in substance) are very reactive. Their interesting properties
can be illustrated by their behavior with triorganylmetal chlorides of the germanium, tin, and lead series.
In solution they react readily, forming symmetrical and
unsymmetrical formal analogues of thio-, seleno-, and
telluro-ethers according to reaction (e).
RSMX-Li
+ Cl-M'R,
=
Ge, Sn, or Pb; X
= S,
151
145
119
148
I38
101
1 M.p. ["C] I Ref
Compound
120(decomp.)
145
117
150
136(decomp.)
129
(el
+ LiCl+ R3M-X-M'R3
R = CsHS or CH3; M, M'
I M.p. ["Cl 1 Ref.
Compound
Se, or Te
This reaction opens a simple preparative route to a
class of compounds of which only a few representatives
have been synthesized, by a considerably more circuitous method. No covalent germanium-, tin-, or leadtellurium compound has been described previously.
Table 1 summarizes the compounds obtained by
reaction (e).
Other reactive halogen compounds behave analogously,
as shown by the synthesis of SS-diphenyltin bis(thiobenzoate) (S) [2*1.
The hexaphenyl compounds listed in Table 1 all crystallize
readily; the sulfur compounds are colorless, the selenium
compounds have a yellow tinge, and the tellurium compounds
are yellow. They are readily soluble in anhydrous organic
I221
I221
[221
1231
[231
1241
I M.P. I "Cl/ B.P. I "Clmm] 1 Ref.
Compound
-22
-27
68/12
63/10
90/12
94/12
79/12
7211
-
8
-12
-19
-6
solvents such as benzene, dioxane, tetrahydrofuran, and
chloroform. Particularly noteworthy is their thermal stability
and, in many cases, their resistance t o solvolysis.
Final statements cannot yet be made about the bonding in
molecules of the type R3M-X-MR3.
Help should come
from X-ray determination, now in progress, of the valence
angles at the chalcogen atom, about which information will
also be provided by further evaluation of the infrared spectraC341 - these are almost identical in the NaCl region.
Skeletal vibrations of the sulfur compounds occur between
250 and 4OOcm-1 (CsBr region); their assignment is given
in Table 2. Corresponding bands are to be expected at still
longer wavelengths for the Se and Te compounds.
The stability of Si-0-Si bonds, which is so important
in inorganic Nature, is ascribed to a noteworthy contribution by (p-d), bonding between oxygen and
Table 2. Wave-numbers [cm-11 of M-S vibrations of hexaphenyl sulfides [*I. (For clarity the phenyl and
phenyl-metal vibrations are not included; s t = strong, rn = medium).
Assignment
Ge-S-Ge
vas (Ge-S-Ge)
vas (Sn-S-Sn)
Y ~ (Pb-S-Pb)
S
417 st
Sn-S-Sn
Pb-S-Pb
404 m
355 m
Ge-S-Pb
I Sn-S-Pb
400 m
317 m
365 m
305 m
385 m
330 m
278 m
vs(Pb-S-Pb)
Perkin-Elmer Model 221, CsBr optics, in Nujol suspension.
[28] H. Schumann, K . F. Thom, and M . Schmidt, J. organomet.
Chemistry 2, 97 (1964).
[29] R. K. Ingham, S. D . Rosenberg, and H. Gilman, Chem.
Reviews 60, 459 (1960).
1301 G . Griittner, Chem. Ber. 51, 1303 (1918).
Angew. Chem. internat. Edit.
I
336 st
vs(Sn-S-Sn)
['I
Ge-S-Sn
376 st
v(Ge-S)
v(Sn-S)
v(Pb-S)
vs(Ge-S-Ge)
I
Vol. 4 (1965) I No. 12
L311 M . Schmidt and H.
Chem. 73, 64 (1961).
1321 M. Schmidt and H . RuA Chem. Ber. 96, 784 (1963).
1331 H . Schumann and M . Schmidt, unpublished work.
[34] H. Schumann and M. Schmidt, J. organornet. Chemistry 3 ,
485 (1965).
1009
silicon. If the bridging oxygen atom of disiloxanes is
replaced by the larger sulfur atom the stability decreases drastically: Si-S bonds are extremely susceptible to hydrolysis. However, study of the new chalcogen
derivatives R3M-X-MR3 of Table 1 shows that the
stability increases on simultaneous increase in the size of
the bridgehead atom M and the bridging atom X: the
grouping Ge-S-Ge is more stable than Ge-0-Ge,
although Ge-Se-Ge is, on the contrary, very sensitive
to hydrolysis. Again, Sn-Se-Sn compounds do not
react with water and can even be recrystallized from
alcohol. Thus the relations between Sn-Te-Sn and
Sn-Se-Sn groupings are similar to those between
Si-S-Si and Si-0-Si groupings. In consequence the
Pb-Te-Pb grouping is again very stable; the hexaphenyl derivative is not attacked even by boiling water.
Analogous observations were made for unsymmetrical
“ethers.” For example, Ge-Se-Pb and Sn-Te-Pb
linkages resist hydrolysis, whereas compounds with
Ge-Se-Ge and Sn-Te-Sn groups can be handled only
in an anhydrous atmosphere. The hexamethyl compounds have similar properties.
Ascribing these findings to the (p-d), constituents of the
M-X-M linkages for the heavier elements (given suitable
size relations in M:X), although seeming at first sight a
plausible interpretation, is certainly too primitive because dthe very small energy contribution from overlap of of
orbitals of the heavier atoms.
b+ 6-
R3Sn-R + @ ..S - ( ..S )x - S..O
--p
R&hS-(S),-S-R
(9)
R-iSnR3 j
R,Sn-Si-(S),fS-R
(x+2) R3Sn-S-R
+
x R-iSnR3
R = C&fs
(6)
chain - occurs analogously to Scheme (c). The triphenyltin thiophenoxide (6) 1361 to be expected from reactions (g) is unstable at 200 “C and can therefore not be
isolated. The degradation thus proceeds further in
accordance with Scheme (h).
RS-Sn-R
fi,+ b-
+
F
@:S-SX-So e RS-Sn-S-S,-S-R
R
R
51
R-jSnRzSRi
RS-Sn-S-(S),j-SR
R
j x R-$nRzSR
-
(h)
(x+2) RzSn(SR)2
(71
R = CsHs
Diphenyltin dithiophenoxide (7), which has been
prepared by a different route [361, decomposes appreciably below the reaction temperature, eliminating
diphenyl sulfide to give diphenyltin sulfide (formally
analogous to the silico-ketones = silicones) which is not
stable as monomer and yields the trimer (7).
IV. Phenylation of Chalcogens by
Tetraphenylstannane
Bond fission of molecular sulfur by nucleophilic reagents
occurs under quite mild conditions [I]. Relations are
apparently quite different if tetraphenylstannane is
treated with sulfur. Sn(C6H5)4 is one of the most stable
organometallic compounds; it can, for example, be
heated for several h m r s at about 500 “C (b.p. 425 “C/
760 mm) without decomposing. Nevertheless it reacts
with sulfur at as low a temperature as 200 “C. As early
as 1929 Bost and Borgstrom 1351 observed that diphenyl
sulfide is thus formed, but, remarkably, they did not
study the fate of the tin in this reaction.
We have found1361 that the reaction takes place in a
sealed tube at about 200°C, according to the overall
equation (f). At this temperature, SnR4 is polarized by
3 Sn(CsH5h
+6s
+
3 s(csH5h
+ [(CsH~)zSnSl3
(f)
s+ sthe “polar solvent” sulfur [*I in such a way (R3Sn-R)
that a phenyl anion is foreshadowed and then, as a
nucleophilic reagent, degrades the sulfur chain as shown
in reactions (g). The degradation there outlined - without statement of the electron distribution in the sulfur
[35] R. W. Bost and P. Borgstrom, J. Amer. chem. SOC.512, 192
(1929).
[36] M. Schmidt, H. J. Devsin, and H. Schrimonn, Chem. Ber.
95, 1428 (1962).
[“I Above the %iscositymaximum at co. 160 “C a sulfur melt has
clearly a polarizing action, owing to the presence of some
@
s -(
S)x-
1010
s :e.
Good yields can be obtained of the products of sulfurdegradation, during which process the degrading agent
is first formed from a reaction partner that has a
polarizing action at high temperatures. Tin-sulfur sixmembered rings are very stable; they are not attacked
by boiling water. These compounds crystallize readily
and are soluble in many organic solvents. If Sn(CsH5)4
is treated with a sufficient excess of sulfur, further
phenyl anions are removed and high-polymeric products are formed in which rings (8) are linked by sulfur
bridges [37]. A temperature in excess of 220 “C leads - in
principle by the same mechanism - to complete dephenylation of the tin compound, with formation of diphenyl sulfide and alloy-like “tin sulfides” which are
also obtainable from the cyclic compounds (8) and the
higher-polymeric subsequent products :
(RZSnS)3+ 3x S
--f
3SnSx+ 3 R2S
(8)
Tetrabutylstannane - and the alkyl derivatives in
general - react with sulfur even at lower temperatures.
At as low as approximately 150 “C, reaction (k) occurs
(for reaction of organyltin chlorides with sulfur see 9.
3 (C4HghSn
+ 6S
--f
KC4H9hSnS13
+ 3 (C4H9hS
(k)
[37] M. Schmidt and H . Schumann, Chem. Ber. 96, 462 (1963).
1381 H. Schumann and M. Schmidt, Chem. Ber. 96, 3017 (1963).
Angew. Chem. internat. Edit. [ Vol. 4 (I965) / No. I 2
Because of the lesser polarity of their "metal"-carbon
bond, tetraphenyl derivatives of the lighter analogues of
tip react only at higher temperatures [*I; the intermediates are no longer stable. Ge(C&)4 affords GeS,
and diphenyl sulfide above 270 "C [39], and Si(C&)4 affords SiS, above 380 "C 1391. The higher reactivity of the
n-butyl conipounds, on the other hand, still permits
isolation of trimeric, cyclic dibutylgermanium sulfide
[analogous to (811 and (C4H&Si-S-Si(C4H9)3,
in
addition to (n-C4Hg)zS, these products being formed by
transalkylation 1391.
Selenium is also phenylated by tetraphenyltin at about
200 "C. Triphenyltin selenophenoxide (9) [**I
is
isolated in good yield as intermediate 1401. Above 240 "C
diphenylselenium (and some RzSe2) are formed alongside tin selenides, and above 270 "C also selenanthrene
[cf. formula (IZ)]. Sn(C4H9)4, however, reacts at 200 "C
with selenium (401 according to Equation (I), analogously
V. Phenylation of Phosphorus by
Tetraphenylstannane
The hypothesis developed "1 for element-element bonding in sulfur chemistry is valid equally for other elements
from the second Period onwards, and for those of the
third and fifth main Group. Compounds of these
elements with themselves act electrophilically, as do the
chalcogens (cf. the reaction of P4 with Grignard reagents
discovered independently by Rauhut and SernselL421 and
by ~81331).Thus phosphorus should, like sulfur, react
with tetraphenylstannane at high temperatures. The
tervalency of phosphorus, of course, complicates matters
and makes a direct Comparison more difficult. In practice, elementary phosphorus reacts with tetraphenylstannane in a sealed tube above about 235 "C. At higher
temperatures the end products are tin phosphide and
triphenylphosphine, according to reaction (n) [43,441.
(The triphenyl derivatives of As and Sb are also readily
available by this process 1441.) If the temperature is kept
between 235 and 250°C and the ratio P:Sn(C6H5)4 is
varied, an intermediate product of the degradation of
phosphorus by carbanions can be isolated: (12) (m.p.
= 110 "C, yellow, spontaneously inflammable in air),
(13) (yellow oil, extremely sensitive to oxidation), (14)
(m.p. 66 "C, colorless).
to sulfur. The corresponding phenyl derivative was
obtained on treatment of R3Sn-SeLi with R2SnC121231,
in accordance with reaction (m).
2 R3Sn-SeLi + RzSnClz
-
P
k
R3Sn-Se-Sn-Se-SnR3
(m)
+
R
=
1
'3
(RzSnSe)s + R3Sn-Se-SnR3
c6H5
Reaction between tellurium and tetraphenyltin sets in,
slowly, only above 240 "C; after several days it leads to
good yields of diphenyltellurium and tin tellurides C411.
If the temperature is raised above 310 OC, there is fornied
the previously undescribed and remarkably air-sensitive
telluranthrene (ZI) (m.p. 188-190 "C), as well as benzene.
Covalent tin-phosphorus compounds which, with two
exceptions [45,4*1, were previously unknown, generally
are extremely sensitive to oxidation, which greatly
increases the difficulty of isolating them from the
complex reaction mixture. The products of oxidation
of the tin phosphines occurring in these mixtures can,
however, be obtained, cleaved with caustic soda into
characteristic fragments, and thus analysed [*I. Table 3
shows the oxidized decomposition products obtained.
-
..-
[*I Tin was determined [49] by X-ray emission analysis, along-
[*I Pb(CdH& probably reacts
by a free-radical mechanism [391.
[39] M . Schmidt and H . Schurnann, Z. anorg. ally. Chem. 325,
130 (1963).
[**I Existence of the sulfur analogue (C6H5)3Sn-SC6H5 has
been only inferred.
[401 M . Schmidt and H. Schumann, Chem. Ber. 96, 780 (1963).
[411 M . Schmidt and H . Schuinnnir, Z. Naturforsch. 19b, 74
(1964).
Angew. Chem. internat. Edit.
1 Vol. 4 (1965)
No. 1-3
side photometrically determined phosphorus.
[42] H. Rauhut and P. Semsel, J. org. Chemistry 28, 473 (1963).
[43] H . Schumann, H . KOpL and M. Schmidt, Angew. Chem. 75,
672 (1963); Angew. Chem. internat. Edit. 2, 546 (1963).
1441 H. Schumann, H. KOpA and M . Schmidt, 2. anorg. allg.
Chern. 331,200 (1964).
[45] H. Schurnann, Ff. KOpL and M . Schmidt, Chem. Ber. 97, 1458
(1 964).
[46] H. Schuniann, H . Kopf, and M . Schmidt, Z. Naturforsch.
196, 168 (1964).
[47] A . B. Bucker, F. 8.Balashown, and I. S. Soborovskii, Dokl.
Akad. Nauk SSSR 4, 843 (1960).
[48] W. Kirchen and H . Buchwnld, Chem. Ber. 92, 227 (1959).
1011
Table 3. Oxidation products isolated as secondary products from the
reaction of Sn(C6Hs)r with Px between 235 and 260% (R = GHs).
I
Fragments
I
Structural units of
I
tin phosphonate
original
stannvlohosohine
9
bI
I
R2Sn-0-PR
I
fl
I
1
R$n-TR
I
RSn-0-P-0-
I
Q
I
R2P-O-Sn-O-P-O-
The second series of compounds (I8)1511 is formed in
good yield by reaction (p). (Use of alkali-metal diphenylphosphides in place of the free phosphine leads to com-
1
R2P-Sn-P-
I
I
+ n HP(C6Hs)z + n (CzHs)3N
(CsHs)4-nsn[P(CsHs)2In + n (GHs),N-HCl
(C6H5)4-nSnCI,
+
P
B
R2P-O-$n-O-PR
"
!
RSn-P-
P
9 1
c,I
although the reaction mechanism is not yet finally clarified, the cyclic compounds (16) (m.p. 60 "C)149,501 and
( 1 7) (m.p. 101 "C)[501 are obtained in satisfactory yields
alongside hexaphenyldistannane, triphenylphosphine,
and lithium chloride.
I
R2P-Sn-PR
kl
P
(P)
(18)
plications [521.) The compounds (18), like the tin phosphines described above, crystallize readily and are soluble in organic solvents. Table 4 presents the organylstannylphosphines prepared by reactions (0)and (p) or,
in the meanwhile, by other authors analogously L531 or
from stannylamines [541.
R
I t
(RP-Sn)2-PR
I
P
(RP-Sn)S-P
I 1
Table 4. Monomeric organylstannylphosphines.
M.p. [ "C]
B.p.
["Clmml
VI. Syntheses of Covalent Tin-Phosphorus
14210.7
Compounds
10010.2
16810.7
The above "direct synthesis" having shown that a
variety of previously unknown tin-phosphorus cornpounds can exist, we wished to prepare such compounds
systematically. Only phenyl groups were used to render
the tin and phosphorus inert. Two series of compounds
appeared suitable as models. The first is derived from
triphenylphosphine by replacement of one, two, or all
three phenyl groups by triphenyltin. The second is
derived in the reverse direction from tetraphenylstannane, by replacement of one, two, three, or four
phenyl groups by diphenylphosphino groups.
The first series of compounds is formed in tetrahydrofuran in good yield on reaction of lithiotriphenylstannane with appropriate phosphorus chlorides according
to reaction (0)1501. The colorless crystalline products
(15) dissolve readily in anhydrous organic solvents.
n (C&s)3SnLi f (C6Hs)3-nPCIn
+
[(CaHs)3sn]nP(CsHs)s-n
+ n Licl
(0)
(15)
However, the products (15) arise only if the phosphorus
chloride is present in excess until the end of the reaction.
Otherwise, the primary reaction products are cleaved by
the strongly nucleophilic triphenyltin anion. In this way,
[491 C. Mahr, H. Klamberg, and G. Storck, unpublished work.
[ S O ] H. Schumann, H. KOpA and M. Schmidt, Chem. Ber. 97,
3295 (1964).
1012
96
130
114'
102
80
117
107
150
20 1
Ref.
153, 541
148, 53, 541
1531
7010.2
17710.6
I531
126/0.3
19210.6
1531
[531
151, 531
[SO,51, 531
~511
(511
151, 531
1511
1511
[Sol
[501
This process is suitable also for the preparation of analogous
germanium and lead compounds, e.g., (CzHs)3Ge-P(C6H5)2
(b.p.
146 ' C / w 3 mm)cssI, (C6H5)3Ge-P(C6H5)2 (m.P.
108
[331,
[(C&&Ge]3P
(mp.
192 "C)1331,
and
(C&~)JP~-P(C~H
(decornp.
~)~
100 "C) [561.
"c)
Covalent tin-phosphorus compounds are sensitive to
oxygen (they do not react with oxygen-free water). The
degree of this sensitivity depends considerably on the
nature of the "shielding" organic radicals. Thus alkyl
derivatives are, in general, less stable than the phenyl
analogues. Tetrakis(dipheny1phosphino)stannane on
_-_
[51] H. Schumann, H. KOpL and M. Schmidt, J. organomet.
Chemistry 2, 159 (t964).
[52] H. KOpf, Dissertation, Universitat Marburg, 1963.
I
G.
.M. Campell, G. JV.A . Fowles, andL. A . Nixon, J. chem.
[53] .
SOC. (London) 1964,1389.
[S4] K. Jones and M . F. Lappert, Proc. chem. SOC.(London) 1964,
22.
[ 5 5 ] F. Glockling and K. A. Hooton, Proc. chem. SOC. (London)
1963, 146.
[56] H. Schumann, P. Schwabe, and M . Schmidt, J. organomet.
Chemistry I, 366 (1963/64).
Angew. Chem. internat. Edit. 1 Vol. 4 (1965)/ No. I 2
the one hand and tris(triphenylstanny1)phosphine on
the other react only slowly with air. The cyclic compounds are considerably more sensitive to oxygen. Unsymmetrical stannylphosphines can, however, be handled
only in an oxygen-free atmosphere [*I. The oxidation
occurs, in principle, according to reaction (9). either
>Sn-P< +
o2 +
9,
3Sn-0-P,
(4)
simply in air or, always quantitatively, with hydrogen
peroxide in alcohol [50,511.
Infrared spectra1331 show that, with a n excess of oxygen, one
0 atom first adds to the lone electron pair of phosphorus.
Suppositions that this is the only and final reaction step 1571
are contradicted by the experimental facts. It seems that the
structure ( 1 9 a ) rearranges to (I9b) in a reversal of the
Arbusov rearrangement. Then a further oxygen atom adds t o
.
the phosphorus according to reaction (r), giving ( 1 9 ~ ) The
oxidation products of monomeric organylstannylphosphines
are listed in Table 5.
The new phosphinic esters can be cleaved, like the parent
stannylphosphines, by hot sodium hydroxide solution to
characteristic, readily detected fragments [50,511.
Questions about the nature of the (certainly covalent)
bonding between the metal and phosphorus cannot yet
be answered. Physical studies (infrared, Raman, crystal
structure) should provide relevant information. Any
considerable contribution from (p-d), bonding, as
required between Sn and PI531 and indeed between Sn
and NI58l (2p and 5d orbitals), seems to us to be excluded by our results and by infrared and N.M.R.
investigations. The same applies to the arsenic, antimony, and bismuth compounds r59.601 listed in Table 6,
Table 6. Organylstannyl-, organogerrnanyl-, and organylplumbylarsines, -stibines, and bismuthines.
Compound
M.p. ["Cl
B.P.
[Wmml
136/0.05
143/0.15
161/0.2
164/0.09
Table 5. Oxydation products of organylstannylphosphines.
Organyltin phosphinate
M.p. I "Cl
Ref.
> 360
247
226
215
> 360
>250
372
> 230
> 250
216
174
> 290
150
119
80 (decornp.)
85 (decornp.)
70
115
216
114
118 (decomp.)
146/0.18
170/0.13
i m/o. I 5
215
138 (decomp.)
not discussed in this paper. The investigations to date
show clearly, at any rate, that tin, germanium, and lead
can, just like carbon, form stable electron-pair links
with elements of the main Groups.
[ * ] This has not always been taken into account, e.g., when
considering the infrared frequency data for ( C ~ H ~ ) ~ S ~ - P ( C ~ H ~ ) Z
We are grateful to Dr. H. Kopf for collaboration and sugand (C2H5)3Sn-P(C6H& 1531. The bands found at 1130 and
750 cm-1, and at 1145 and 760 cm-1, respectively, are certainly
gestions in the study of the sensitive Sn-P compounds,
P=O and Sn-0 valence vibrations, respectively.
also to Dr. K. F. Thomfor work on the tin chalcogenides.
[57] H. Schindlbauer and D . Hammer, Mh. Chem. 94,644 (1963).
We thank Dr. H . Dersin and Miss T. Ostermannfor ex[58] J . Lorberth and M . R . Kula, Chem. Ber. 97, 3444 (1964).
perimental help and the Fonds der Chemischen Industrie
1591 H. Schumann and M . Schmidt, Angew. Chem. 76,344 (1964);
and the Deutsche Forschungsgemeinschaji for financial
Angew. Chem. internat. Edit. 3, 316 (1964).
support.
[60] J. G . M . Campell, G . W. A . Fowles, and L. A . Nixon, J. chem.
SOC.(London) 1964, 3026.
Received: February 8th, 1965
[A 4671256 I€]
1611 H . Schumann and M . Schmidt, Chem. Ber., in press.
German version: Angew. Chem. 77, 1049 (1965)
Angew. Chem. internat. Edit.
Vol. 4 (1965)
1 No. 12
1013
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