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Carbamoyl Isothiocyanates.

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hydrogenation. Under the above conditions 1,3-diphenyl[1,2,3]triazolo[5,1-b]benzimidazoliumbromide (3), m.p.
195°C (corresponding BFf salt, m.p. 19OoC), is at once
precipitated in 72% yield after reaction with one equivalent
of N-bromosuccinimide. Compound (3) can be considered,
not only as a triazolium salt analogous to (2), but also as a
hydrobromide (‘3’). Thus, with aqueous pyridine it gives the
white crystalline free base 1,3-diphenyl[l,2,3]triazolo[l$a]benzimidazole (4), m.p. 148 “C, in 88 % yield.
The isothiocyanate ( I ) predominates strongly in toluene at
2OoC (IR band at 1975-1985 cm-1); the isocyanate component (IR band at 2220 cm-1) is detectable only on use of thick
layers (0.1 mm), but increases appreciably in a reversible reaction if the temperature is raised to 40-50 “C.
The chemical reactions are determined by this dualism. Thus
rapid action of an excess of H 2 0 leads to derivatives
of the isothiocyanate, but slow reaction
(exposure to air) leads to derivatives (R2N-CS-NHz) of the
isocyanate. Schiff bases react with (2) only (cycloaddition to
In most of the reacgive 2-amino-l,3,5-thiadiazin-4-ones).
tions, the isothiocyanate predominates e.g. in addition of
benzylamine, aniline, or p-nitroaniline to give carbamoylthioureas, or of acetylacetone imine to give derivatives of 3aminothiocrotonamide; 1,2-cycloaddition of diazomethane
to give 1,2,3-thiadiazoles; 1,4-cycloaddition of Az,z’-bi(l,3diphenylimidazolidine) or t-butyl, cyclohexyl, phenyl, or p methoxyphenyl isocyanide to give derivatives of 1,3-oxazole4-thione.
When kept for some time, some of the undiluted compounds
( I ) + (2) yield colorless, crystalline “dimers” ( 3 ) I(3a)
The structures of compounds (3) and (4) have been proved
by elemental analysis and I R spectra. The starting material,
( l a ) with N H in place of S, gives sharp N H bands at 3400
cm-1 and 3300 cm-1, compound (3) gives a n intense broad
band at 2600 cm-1 characteristic of the NH@ group, but
compound (4) gives no N H band. A remarkable property of
the new ring system (4) is the intense blue fluorescence of its
[Z 429 IEI
Received: January 23rd, 1967
German version: Angew. Chem. 79, 272 (1967)
[*I Dr. A. Messmer and Dip1.-Chem. A. GellCri
Central Institute for Chemistry Research of the
Hungarian Academy of Sciences
Pusztaszeri ut 57/69
Budapest I1 (Hungary)
[l] Part 3 of New Heteroaromatic Azolium Salts.-Part 2: 131.
[ 2 ] R. Kuhn and W. Miinzing, Chem. Ber. 86, 858 (1953).
[3] A . Messmer and 0. Szimrin, Angew. Chem. 77, 1077 (1965);
Angew. Chem. internat. Edit. 4, 1074 (1965).
[4]A . Messmer and A . GeNPri, Angew. Chem. 77, 171 (1965);
Angew. Chem. internat. Edit. 4, 154 (1965).
[5] V. M . Zuborovsko, 2. obit. Chim. 21, 2199 (1951); Chem.
Abstr. 46,8097f (1952).
[6]L. Bystricky and M . Przeworsky, Ber. dtsch. chem. Ges. 45,
3499 (1915).
Carbamoyl Isothiocyanates
By J. Goerdeler and D . Wobig[*I
By reaction according to the scheme
we have obtained compounds of type ( I ) , most of them as
oils that are difficult to purify (R = CH3, C2Hs. allyl, n-C4Hg,
piperidino, or morpholino), but in one case as a crystalline
solid (R = cyclohexyl; m.p. 101-102°C).
The carbamoyl isothiocyanates ( I ) are in equilibrium with
the corresponding thiocarbamoyl isocyanates (2) [I], as can
be seen from the I R spectra and from chemical reactions.
R = CH3, m.p. 198-199 “C (decomp.); (3b) R = CzH5, m.p.
104 “C (decomp.)], probably by cycloaddition of one molecule each of ( I ) and (2).
Received: January 17th, 1967;
revised: January 31st, 1967
[Z 431 IE]
German version: Angew. Chern. 79, 272 (1967)
[*] Prof. Dr. J. Goerdeler and Dip1.-Chem. D. Wobig
Organisch-ChemischesInstitut der Universitat
Meckenheimer Allee 168
53 Bonn (Germany)
[l] According to I. Goerdeler, H. Schenk, and K. Jonas, Chem.
Ber. 98, 2954 (1965); 99, 3572 (1966), these can be prepared as
metastable compounds by thermal cleavage of 2-aminothiazoline4,5-diones.
Dithioacetylacetonatoiron Complexes [**I
By K . Knauer, P. Hemmerich, and J . D . W . vun Voorst [*I
Stable iron mercaptide clusters as found in ESR- and redoxactive nonheme iron proteins (e.g. ferredoxin [ I ] and Feflavoproteins [21 stimulate the search for model compounds
which reflect the structure of FeS-, FeSS- and FeSSFe-groups
as a function of the oxidation state and provide a basis for
structural assignments of spectral d a t a W
The iron-mercaptide system is defined by equation (a).
Fe3+ + SR-
(FeIWR t)FeItSR)$+
Equilibrium positions, the value of n, kinetic stability,
structure, and magnetochemistry of intermediates will be
widely varying functions of the iron ligand fields and of the
steric and electronic requirements inherent to R.
It has been shown earlier, that organic disulfides RSSR and
Cur may react to give strongly colored CuSSCu-clusters “41. A
similar affinity for RSSR may be associated with low spin
d6-iron. Unfortunately, the two requirements of strong
ligand field for preservation of spin state and binding of the
relatively weak RSSR-ligand, seem to be mutually exclusive.
We have found that a new stable FeSS-system is formed on
reaction of dithioacetylacetone [51 in statu nuscendi with Fe3’
according to equation (b).
Angew. Chem. internat. Edit. 1 VoI. 6 (1967) ,INo. 3
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carbamoyl, isothiocyanate
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