Sterically protected dipotassium germanedithiolate

Article abstract of DOI:10.1246/cl.2001.964

The germanedithiols Dmp(Ar)Ge(SH)₂ [Dmp=2,6-dimesitylphenyl; Ar = Dep (2,6-diethylphenyl) 1a, Tip (2,4,6-triisopropylphenyl) 1b] were synthesized by the reduction of hexathiagermepanes Dmp(Ar)GeS₆ and tetrathiagermolanes Dmp(Ar)GeS₄ with NaBH₄. The treatment of 1a with 2 equiv of potassium hydride afforded the dipotassium germanedithiolate 2.

Full text of DOI:10.1246/cl.2001.964

964
Chemistry Letters 2001
Sterically Protected Dipotassium Germanedithiolate
Tsuyoshi Matsumoto and Kazuyuki Tatsumi*
Research Center for Materials Science, and Department of Chemistry, Graduate School of Science, Nagoya University,
Furo-cho, Chikusa-ku, Nagoya 464-8602
(Received July 5, 2001; CL-010628)
The germanedithiols Dmp(Ar)Ge(SH)2 [Dmp=2,6-di-
r.t. worked effectively to afford 1a in 83 and 79% yields from
3a and 4a, respectively. A similar reduction of the mixture of
3b and 4b also gave 1b in 82% yield.8
mesitylphenyl; Ar = Dep (2,6-diethylphenyl) 1a, Tip (2,4,6-tri-
isopropylphenyl) 1b] were synthesized by the reduction of
hexathiagermepanes Dmp(Ar)GeS6 and tetrathiagermolanes
Dmp(Ar)GeS4 with NaBH4. The treatment of 1a with 2 equiv of
potassium hydride afforded the dipotassium germanedithiolate 2.
1
In H NMR spectra the singlet peaks attributable to GeSH
were observed at 0.52 (1a) and 0.63 ppm (1b).9 The Raman
spectra of 1a shows two S–H stretching bands at 2564 and 2552
cm–1, which are shifted to 1863 and 1854 cm–1 for
Dmp(Dep)Ge(SD)2.10 Similar S–H stretching bands were
observed at 2583, 2563 cm–1 for 1b. The relatively strong
Ge–S stretching bands appear at 383.3 and 370.0 cm–1 for 1a
and 384.5 and 370.1 cm–1 for 1b, which are similar to the value
reported for Me3GeSMe, 385 cm–1.1,11
Although organogermanium compounds have attracted
attention as potential functional materials,1 the chemistry of
chalcogen containing germanium compounds is not well inves-
tigated. Compounds having two or more Ge–SH functions are
useful precursor of heterocycles containing germanium, and in
fact dithiagermatitanacycles and their zirconium analogue were
synthesized by Steudel2 and Ando.3
The structural properties of organogermanethiols have not
been well studied and X-ray crystallographic data are limited to
Cy3GeSH (Cy = cyclohexyl).4 In addition, no structural data on
their thiolato anions have been reported.
The structure of 1a is shown in Figure 1.12 The Ge–S bond
lengths are 2.2388(9) and 2.2283(8) Å, which are slightly
shorter compared with that of Cy3GeSH [2.253(2) Å] reported
earlier.4 The intramolecular S(1)–S(2) separation is 3.408(1) Å
and no significant intermolecular contact was observed between
the mercapto groups.
The synthetic route to germanethiol is limited to the fol-
lowing two methods; (1) reaction of elemental sulfur with
hydrogermanes; (2) nucleophilic substitution of the haloger-
manes by H2S in the presence of amines.1,3,5 We previously
reported the synthesis of hexathiagermepanes 3a,b and tetrathi-
agermolanes 4a,b via sulfurization of dihydrogermanes,
Dmp(Ar)GeH2 [Dmp=2,6-dimesitylphenyl, Ar = Dep (2,6-
diethylphenyl), Tip (2,4,6-triisopropylphenyl)].6 We sensed
that the polysulfides could be good precursors for the synthesis
of Ge–SH function. Reported in this paper is the successful
isolation of the dimercaptogermanes, Dmp(Ar)Ge(SH)2 1, from
reduction of the polysulfides 3 and 4 (Scheme 1).
The dipotassium germanedithiolate, K2[Dmp(Dep)Ge(S)2]
2, was prepared by addition of 2 equiv of potassium hydride to
a THF solution of 1a. The Raman spectra of the potassium salt
in solid show a broad band at 400.1 cm–1 for the Ge–S vibra-
tion, which is slightly shifted to higher frequency compared
with 1a. This shift indicates a partial Ge–S double bond char-
acter arising from the resonance form shown in Scheme 2,
although weak interactions between potassium cations and the
sulfur atoms may exist.
The treatment of 3a with LiAlH4 in THF at r.t. turned out
to give dihydrogermane, Dmp(Dep)GeH2, quantitatively. In
contrast, reduction with NaBH4 in THF generated dimercap-
togermane 1a, although the reaction proceeded very slowly due
to low solubility of NaBH4 in THF. Upon warming the reaction
system up to 40 °C, partial reduction of Ge–S bonds occurred to
give an unseparable mixture of Dmp(Dep)Ge(SH)H and 1a.7
The addition of a small amout of ethanol to the THF solution at
The compound 2 was crystallized from toluene in the pres-
ence of 18-crown-6. The resulting colorless crystals were sub-
jected to X-ray analysis, and the salt was formulated as [2(18-c-
6)(H2O)].12
The crystal structure is shown in Figure 2, where K(2) is
coordinated by H2O[O(7)], S(1), S(2), and S(1*). Thus [2(18-
c-6)(H2O)] is crystallized in a dimeric form. Another potassi-
um cation K(1) is coordinated by S(2) and 18-c-6. The Ge–S
Copyright © 2001 The Chemical Society of Japan

Chemistry Letters 2001
965
4
5
6
7
F. Brisse, F. Bélanger-Gariépy, B. Zacharie, Y. Gareau,
and K. Steliou, New J. Chem., 7, 391 (1983).
Y. Cai and B. P. Roberts, Tetrahedron Lett., 42. 763
(2001).
T. Matsumoto, Y. Matsui, Y. Nakaya, and K. Tatsumi,
Chem. Lett., 2001, 60.
The generation of Dmp(Dep)Ge(SH)H was confirmed by
1H NMR (δ 6.03 ppm GeH, CDCl3) and EI-MS [m/z 554
(M+)].
1
8
1a: colorless crystals; H NMR (CDCl3, 500 MHz) δ 0.52
(s, 2H), 1.03 (t, J = 7.6 Hz, 6H), 1.97 (s, 12H), 2.27 (s,
6H), 2.30 (br m, 4H), 6.74 (s, 4H), 6.82 (d, J = 7.6 Hz,
2H), 7.01 (d, J = 7.6 Hz, 2H), 7.14 (t, J = 7.6 Hz, 1H), 7.45
(t, J = 7.6 Hz, 1H). Anal. Calcd for C34H40GeS2: C, 69.76;
H, 6.89; S, 10.95%. Found: C, 69.65; H, 6.94; S, 10.32%.
1
1b: colorless crystals; H NMR (CDCl3, 500 MHz) δ 0.63
(s, 2H), 0.85 (d, J = 6.9 Hz, 6H), 1.01 (d, J = 6.9 Hz, 6H),
1.22 (d, J = 6.9 Hz, 6H), 1.93 (br s, 12H), 2.30 (s, 6H),
2.81 (sept, J = 6.9 Hz, 1H), 3.10 (sept, J = 6.9 Hz, 2H),
6.81 (br s, 2H), 6.83 (s, 4H), 7.01 (br s, J = 7.6 Hz, 2H),
7.42 (t, J = 7.6 Hz, 1H). Anal. Calcd for C39H50GeS2: C,
71.45; H, 7.69; S, 9.78%. Found: C, 71.10; H, 7.90; S,
9.72%.
9
1H NMR of dimesitylgermanedithiol was reported at δ 0.90
ppm (GeSH) in C6D6. See ref 4.
10 The S–H stretching band of (CF3)3GeSH was reported to
shift from 2592 to 1862 cm–1 by deuteration. R. Eujen and
F. E. Laufs, Z. Anorg. Allg. Chem., 561, 82 (1988).
11 D. F. van de Vondel, E. V. van den Berghe, and G. P. van
der Kelen, J. Organomet. Chem., 23, 105 (1970).
12 The data collection was made with a Rigaku-AFC7 diffrac-
tometer equipped with an MSC/ADSC Quantum1 CCD
detector. Crystal data –for 1a: C34H40GeS2, Mr = 585.40,
triclinic, space group P1, a = 8.9817(5), b = 11.966(2), c =
15.694(2) Å, α = 68.505(3), β = 75.288(1), γ = 77.806(1)°,
V = 1504.8(2) Å3, Z = 2, Dcalc = 1.292 g/cm3, T = 193 K,
µ(Mo Kα) = 47.74 cm–1, R = 0.051, Rw = 0.054, GOF =
1.26, 334 variables, 6720 unique reflections [I > 0σ(I)].
bond distances are 2.195(1) and 2.199(1) , which are shortest
Å
among the reported Ge–S single bonds.1,13 The shortening of
the Ge–S bonds by 0.03–0.04 Å on going from 1a to [2(18-c-
6)(H2O)] supports contribution of the resonance form shown in
Scheme 2,14 although the Ge–S distances are considerably
longer than Ge=S distances.15 The K–S distances range from
3.058(2) to 3.230(2) Å, showing that the interactions are weak.
For 2: C46H64GeS2O7K2, Mr = 943.91, triclinic, space
–
group P1, a = 11.5609(7), b = 12.667(1), c = 18.099(2) Å,
α = 101.999(4), β = 102.149(1), γ = 108.640(1)°, V =
2344.4(4) Å3, Z = 2, Dcalc = 1.337 g/cm3, T = 193 K, µ(Mo
Kα) = 47.74 cm–1, R = 0.080, Rw = 0.081, GOF = 1.02, 523
variables, 10066 unique reflections [I > 0σ(I)].
Dedicated to Prof. Hideki Sakurai on the occasion of his
70th birthday.
References and Notes
13 K. M. Baines and W. G. Stibbs, Coord. Chem. Rev., 145,
157 (1995).
1
P. Riviere, M. R.–Baudet, and J. Satgé in “Comprehensive
Organometallic Chemistry II,” ed. by E. W. Abel, F. G. A.
Stone, and G. Wilkinson, Pergamon Press, New York
(1995), Vol. 2, pp137–216, and references cited therein.
J. Albertsen and R. Steudel, J. Organomet. Chem., 424,
153 (1992).
14 A similar shortening of the Si–S bonds was observed for
the silanethiol Ph3SiSH [2.151(1) and 2.150(1) Å] and its
sodium salt NaPh3SiS(H2O)3 [2.079(1) Å]. W.
Wojnowski, K. Peters, E.-M. Peters, and H. G. von
Schnering, Z. Kristallogr. 174, 297 (1986).
2
3
N. Choi, S. Morino, S. Sugi, and W. Ando, Bull. Chem.
Soc. Jpn., 69, 1613 (1996).
15 T. Matsumoto, N. Tokitoh, and R. Okazaki, J. Am. Chem.
Soc., 121, 8811 (1999), and references cited therein.