Addition of chloroform to tetramesityldigermene

Article abstract of DOI:10.1021/om0008530

The addition of chloroform to tetramesityldigermene yields 1,1,2,2-tetramesityl-1-chloro-2-(dichloromethyl)digermane in 25% isolated yield.

Full text of DOI:10.1021/om0008530

590
Organometallics 2001, 20, 590-592
Ad d ition of Ch lor ofor m to Tetr a m esityld iger m en e
Mini S. Samuel, Michael C. J ennings, and Kim M. Baines*
Department of Chemistry, University of Western Ontario, London, Ontario, Canada N6A 5B7
Received October 5, 2000
Summary: The addition of chloroform to tetramesityl-
digermene yields 1,1,2,2-tetramesityl-1-chloro-2-(dichlo-
romethyl)digermane in 25% isolated yield.
presence of an equal amount of two unique mesityl
substituents in addition to a singlet at 6.33 ppm which
integrated for one hydrogen. There was no band ob-
served in the IR spectrum of 1a in the region of 2000-
2100 cm-1, which would have indicated the presence of
a Ge-H bond. In addition to the signals attributable to
the two unique mesityl substituents, a signal at 67.97
ppm was observed in the 13C NMR spectrum of 1a . The
gHSQC spectrum (J set at 180 Hz) revealed a cross-
peak between the signal observed at 6.33 ppm in the
1H dimension and the signal observed at 67.97 ppm in
the 13C dimension. The EI and CI mass spectra of 1a
did not contain a signal that could be attributed to the
molecular ion of an adduct between chloroform and the
digermene. However, using potassium (K+) ionization
of desorbed species (K+IDS) as a mild ionization tech-
nique,6 a signal attributable to the molecular ion of 1a
(+ K+) was clearly evident. From these data, it was clear
that an adduct between chloroform and the digermene
had been obtained, and furthermore, a C-Cl bond of
HCCl3 had regioselectively added to the GedGe bond
to give the chloro(dichloromethyl)digermane, 1a . The
addition of deuterated chloroform to tetramesityldi-
germene resulted in the formation of 1b. As expected,
the 1H (6.33 ppm) and the 13C (67.97 ppm) signals
attributed to the dichloromethyl group in 1a were
In tr od u ction
Since the discovery, in 1982, by Masamune and co-
workers that stable digermenes are readily produced by
the photolysis of cyclotrigermanes, there have been
many reports of the reactivity of these novel com-
pounds.1 However, the reaction between stable di-
germenes and chlorinated methanes is notably absent.
In view of the report by Kira and co-workers on the
addition of halogenated methanes to tetrasilyl-substi-
tuted disilenes2 and a recent report by Mochida and co-
workers on the reaction between transient tetrameth-
yldigermene and carbon tetrachloride,3 we are prompted
to report on our recent research concerning the reaction
between tetramesityldigermene and chloroform.
1
absent from the H and 13C NMR spectra, respectively,
of 1b.
The identity of the product was confirmed by X-ray
crystallography. The molecular structure of 1b is shown
in Figure 1. The crystal data and selected structure
refinement parameters are given in Table 1. All bond
lengths, including the lengths of the Ge-Ge (2.5090(9)
Å) and the Ge-Cl (2.209(2) Å) bonds, and angles fall
within normal ranges (see Table 2).7 The torsion angle
ClGe(2)Ge(1)C(1) is 169.1°.
Resu lts a n d Discu ssion
Chloroform was added to a solution of tetramesityl-
digermene, generated by photolysis of hexamesitylcy-
clotrigermane at -70 °C in toluene in the presence of
triethylsilane.4 The yellow color of the solution im-
mediately disappeared. Removal of the solvent gave
approximately a 1:1 mixture of 1,1,2,2-tetramesityl-1-
chloro-2-(dichloromethyl)digermane, 1a , and the silyl-
The regiochemistry of the addition of chloroform to
tetramesityldigermene as well as the ease of reaction
parallels that observed in the addition of chloroform to
tetrasilyl-substituted disilenes.2 However, the appar-
ently facile reaction between tetramesityldigermene and
chloroform is in contrast with the fact that tetrameth-
yldigermene does not react with chloroform, at least at
a rate greater than 104 M-1 s-1.3 The addition of the
C-Cl bond of HCCl3 to tetramesityldigermene is also
in marked contrast with the addition of the C-H bond
of HCCl3 to the GedC bond of two transient germenes8
or addition of the C-H bond of HCCl3 to the GedN bond
1
germane5 2. The H NMR spectrum of 1a revealed the
(1) For recent reviews on digermene chemistry see: (a) Escudie´, J .;
Ranaivonjatovo, H. Adv. Organomet. Chem. 1999, 44, 113. (b) Baines,
K. M.; Stibbs, W. G. Adv. Organomet. Chem. 1996, 39, 275. (c) Escudie´,
J .; Couret, C.; Ranaivonjatovo, H.; Satge´, J . Coord. Chem. Rev. 1994,
130, 427. (d) Tsumuraya, T.; Batcheller, S. A.; Masamune, S. Angew.
Chem., Int. Ed. Engl. 1991, 30, 902. (e) Barrau, J .; Escudie´, J .; Satge´,
J . Chem. Rev. 1990, 90, 283.
(2) Iwamoto, T.; Sakurai, H.; Kira, M. Bull. Chem. Soc. J pn. 1998,
71, 2741.
(3) Mochida, K.; Kayamori, T.; Wakasa, M.; Hayashi, H.; Egorov,
M. P. Organometallics 2000, 19, 3379.
(4) Dixon, C. E.; Liu, H. W.; Vander Kant, C. M.; Baines, K. M.
Organometallics 1996, 15, 5701.
(5) Baines, K. M.; Cooke, J . A.; Vittal, J . J . J . Chem. Soc., Chem.
Commun. 1992, 1484.
(6) Simonsick, W. J ., J r. J . Appl. Polym. Sci. Appl. Polym. Symp.
1989, 43, 257.
(7) Baines, K. M.; Stibbs, W. G. Coord. Chem. Rev. 1995, 145, 157.
(8) Chaubon, M.-A.; Escudie´, J .; Ranaivonjatovo, H.; Satge´, J . J .
Chem. Soc., Dalton Trans. 1996, 893.
10.1021/om0008530 CCC: $20.00 © 2001 American Chemical Society
Publication on Web 12/30/2000

Notes
Organometallics, Vol. 20, No. 3, 2001 591
Ta ble 2. Selected Bon d Dista n ces (Å) a n d An gles
(d eg) for Mes2Ge(Cl)Ge(CDCl2)Mes2 (1b)
Distance
Angle
Ge(1)-C(1)
2.050(6)
2.5090(9)
2.209(2)
1.746(7)
1.800(7)
C(21)-Ge(1)-C(11)
C(1)-Ge(1)-Ge(2)
C(21)-Ge(1)-Ge(2)
C(41)-Ge(2)-Cl
104.2(2)
105.0(2)
122.8(2)
101.3(2)
96.87(6)
108.8(4)
110.1(2)
104.3(3)
110.9(3)
109.4(2)
110.1(2)
121.9(2)
114.1(2)
115.7(3)
112.5(3)
Ge(1)-Ge(2)
Ge(2)-Cl
C(1)-Cl(2)
C(1)-Cl(1)
Cl-Ge(2)-Ge(1)
Cl(2)-C(1)-Cl(1)
C(31)-Ge(2)-Cl
C(21)-Ge(1)-C(1)
C(11)-Ge(1)-C(1)
C(11)-Ge(1)-Ge(2)
C(41)-Ge(2)-C(31)
C(41)-Ge(2)-Ge(1)
C(31)-Ge(2)-Ge(1)
Cl(2)-C(1)-Ge(1)
Cl(1)-C(1)-Ge(1)
attributed to the differences in the polarity of the double
bonds of digermenes, germenes, and germanimines. We
continue to study the scope of the addition of haloge-
nated methanes to group 14 dimetallenes as well as the
mechanism of these additions.
F igu r e 1. Molecular structure of 1b.
Ta ble 1. Cr ysta l Da ta a n d Str u ctu r e Refin em en t
P a r a m eter s for Mes2Ge(Cl)Ge(CDCl2)Mes2 (1b)
empirical formula
fw
C37H44DCl3Ge2
741.26
Exp er im en ta l Section
temp
wavelength
cryst syst
space group
unit cell dimensions
a
b
c
150(2) K
0.71073 Å
monoclinic
Cc
Gen er a l In for m a tion . All experiments were carried out
in flame-dried glassware under an atmosphere of argon.
Toluene was freshly distilled from sodium/benzophenone.
Chloroform was distilled from phosphorus pentoxide prior to
use. Hexamesitylcyclotrigermane was synthesized according
to the published procedure.13 Photolyses were carried out at
350 nm using a Rayonet photochemical reactor. Low-temper-
ature photolyses were carried out by cooling the sample using
an Endocal model ULT-70 low-temperature external bath
circulator to force cold (-70 °C) methanol through a vacuum-
jacketed Pyrex (350 nm) immersion well.
12.722(3) Å
17.339(4) Å
16.538(3) Å
90°
R
â
101.85(3)°
γ
90°
volume
3570.1(12) Å3
4
Z
1.379 Mg/m3
NMR spectra were recorded on a Varian Gemini 300 or
Inova 400 or 600 spectrometer using benzene-d6 as a solvent,
unless noted otherwise. IR spectra were recorded (cm-1) as thin
films of the compound deposited on NaCl plates from CH2Cl2
density (calcd)
abs coeff
F(000)
cryst size
θ range for data collection
index ranges
1.932 mm-1
1528
0.20 × 0.15 × 0.10 mm3
4.19-26.34°
on
a Perkin-Elmer System 2000 FT IR spectrometer. A
0 e h e 15, 0 e k e 21,
-20 e l e 20
17 665
Finnegan MAT model 8200 mass spectrometer, with an
ionizing voltage of 70 eV, was used to obtain electron impact
or chemical ionization mass spectra (reported in mass-to-
charge units, m/z, with ion identity and peak intensities
relative to the base peak in parentheses). The detailed
experimental procedure to perform K+IDS has been described
elsewhere.6
no. of rflns collected
no. of indep rflns
abs corr
refinement method
final R indices [I>2σ(I)]
R indices (all data)
3621 [R(int) ) 0.0570]
integration
full-matrix least-squares on F2
R1 ) 0.0342, wR2 ) 0.0848
R1 ) 0.0404, wR2 ) 0.0968
Rea ction of Tetr a m esityld iger m en e w ith Ch lor ofor m .
Cyclo-Ge3Mes6 (50 mg, 0.054 mmol) and Et3SiH (0.1 mL,
excess) were dissolved in toluene (4 mL) and photolyzed (350
nm) at -70 °C for 16 h. After irradiation for 16 h, the reaction
mixture appeared clear and bright yellow in color. Upon the
addition of chloroform (2 mL, 0.026 mmol) to the cold solution,
the yellow color of the solution faded to clear and colorless.
The solvent was removed in vacuo to yield an oily white
residue. The product mixture (containing 1a , 2, and oxidation
byproducts14) was separated by preparative thin-layer chro-
matography (silica gel; 50/50 CH2Cl2/hexanes) to yield a 1:2
of two stable germanimines.9 Differences in the reactiv-
ity between digermenes, germenes, and germanimines
and other reagents have been noted previously. For
example, phenylacetylene reacts with Dep2GedGeDep2
(Dep ) 2,6-diethylphenyl) to give a digermetene,10
whereas the C-H bond of phenylacetylene adds across
the GedN bond of two stable germanimines to give
(alkynylgermyl)amines.11 The formal [2 + 2] cycloadduct
is obtained from the reaction between acetone and
Dep2GedGeDep2,10 whereas the formal ene product is
obtained from the reaction between acetone and a stable
germene.12 These differences in reactivity can be
1
mixture of 1a and 25 as determined by H NMR spectroscopy.
This mixture was also separated by preparative thin-layer
chromatography (silica gel; 50/50 CH2Cl2/hexanes) to give
1,1,2,2-tetramesityl-1-chloro-2-(dichloromethyl)digermane, 1a
(10.2 mg, 25%), as a white solid. Mp: 198-199 °C. IR (cm-1):
(9) (a) Rivie`re-Baudet, M.; Khallaayoun, A.; Satge´, J . J . Organomet.
Chem. 1993, 462, 89. (b) El Baz, F.; Rivie`re-Baudet, M.; Ahra, M. J .
Organomet. Chem. 1997, 548, 123.
(10) Batcheller, S. A.; Masamune, S. Tetrahedron Lett. 1988, 29,
3383.
(11) Rivie`re-Baudet, M.; Khallaayoun, A.; Satge´, J . Organometallics
1993, 12, 1003.
(12) Lazraq, M.; Couret, C.; Escudie´, J .; Satge´, J .; Dra¨ger, M.
Organometallics 1991, 10, 1771.
(13) Ando, W.; Tsumuraya, T. J . Chem. Soc., Chem. Commun. 1987,
1514.
(14) Samuel, M. S.; Baines, K. M. To be published.

592 Organometallics, Vol. 20, No. 3, 2001
Notes
3365 (m), 2974 (m), 2921 (m), 1602 (s), 1554 (w), 1449 (s), 1405
(m), 1379 (m), 1289 (w), 1261 (m), 1092 (s), 1049 (s), 951 (w),
880 (w), 847 (s), 802 (s), 701 (w). H NMR (ppm): 6.68 (s, 4H,
480 (Mes374GeCDCl, 41), 362 (Mes274GeCDCl +H, 100), 347
(Mes274GeCl, 30), 328 (32), 311 (Mes272Ge +H, 85), 239
(Mes72GeCCl +H, 50), 121 (MesH +H, 51). MS (m/z): 623
[M+(72Ge74Ge) - CDCl3 +H, 4], 465 (Mes374GeCl -H, 11), 362
(Mes274GeCDCl +H, 15), 347 (Mes274GeCl, 100), 311
(Mes272Ge +H, 53), 237 (Mes72GeCCl -H, 80), 221 (54), 207
(35), 191 (Mes72Ge, 25), 120 (MesH, 56). K+IDS MS (m/z): 780
(M+ + 39, 39). High-resolution MS: M+ - Cl, calcd for
1
Mes CH), 6.65 (s, 4H, Mes CH), 6.33 (s, 1H, CCl2H), 2.46, 2.32
(each bs, 21H total, Mes oCH3), 2.05, 2.03 (each s, 12H total,
Mes pCH3). 13C NMR (ppm): 144.21 (bs), 143.92 (bs), 139.73,
139.32, 138.61 (Mes C), 130.54, 130.28 (Mes CH), 67.97
(CHCl2) 26.52 (bs), 26.03 (bs), 21.19 (Mes CH3). MS (m/z),
CI:isobutane: 705 [M+(72Ge74Ge) - Cl, 23], 583 [Mes72Ge72
-
-
C
37H44D72Ge74GeCl2 706.1393, found 706.1395.
74
Ge(CCl2)Mes2, 9], 479 [Mes374GeCHCl, 49], 395 [Mes2
Crystals of 1b were grown from a saturated solution of
GeCHCl2, 21], 361 (Mes274GeCHCl +H, 100), 347 (Mes274GeCl,
62), 311 (Mes272Ge +H, 65), 277 (24), 237 (Mes72GeCCl -H,
64), 133 (48), 120 (MesH, 18). MS (m/z): 847(7), 727 (13), 623
[M+(72Ge74Ge) - CCl3, 18], 465 (Mes272Ge(Cl)72GeCHCl, 9), 431
(Mes374Ge, 100), 345 (Mes272GeCl, 14), 311 (Mes272Ge +H, 76),
235 (62), 221 (63), 191 (Mes72Ge, 45), 119 (Mes, 55). K+IDS
MS (m/z): 779 (M+ + 39, 100).
hexanes. A crystal suitable for X-ray analysis was selected and
mounted on a glass fiber. Data were collected on a Nonius
Kappa CCD diffractometer using COLLECT software at 150
K. Crystal cell refinement and data reduction was carried out
using the Nonius DENZO package. The crystal data and
selected refinement parameters for 1b are listed in Table 1.
The unit cell parameters were calculated and refined from the
full data set. Selected interatomic distances and angles are
listed in Table 2. Complete details are given in the Supporting
Information.
Addition of d-chloroform (0.05 mL, 0.62 mmol), instead of
chloroform, gave 1,1,2,2-tetramesityl-1-chloro-2-[dichloro(deu-
terio)methyl]digermane, 1b (21 mg, 52%), as a white solid after
purification by chromatography (30/70 CH2Cl2/hexanes). Com-
pound 1b was recrystallized from hexanes to afford clear,
colorless crystals. Mp: 201-202 °C. IR (cm-1): 2922 (s), 1601
(s), 1554 (m), 1448 (s), 1404 (m), 1378 (m), 1289 (m), 1260 (w),
1120 (w), 1026 (w), 846 (s), 805 (m), 719 (m), 706 (m). 1H NMR
(ppm): 6.68 (s, 4H, Mes CH), 6.65 (s, 4H, Mes CH), 2.46 (bs,
12H, Mes oCH3), 2.31 (bs, 12H, Mes oCH3), 2.05 (s, 6H, Mes
pCH3), 2.03 (s, 6H, Mes pCH3). 13C NMR (ppm): 143.89, 143.63
(bs), 139.41, 139.01, 138.27 (bs), 137.59 (Mes C), 130.07 (bs),
129.85 (bs) (Mes CH), 26.11 (bs), 25.72 (bs), 20.98, 20.75 (Mes
CH3). 2H NMR (CHCl3, ppm): 6.29. MS (m/z), CI:isobutane:
706 [M+(72Ge74Ge) - Cl, 50], 672 [M+(72Ge74Ge) - Cl2 +H, 15],
636 [M+(72Ge74Ge) - Cl3, 9], 622 [M+(72Ge74Ge) - CDCl3, 14],
Ack n ow led gm en t. We thank the NSERC (Canada)
for financial support and Dr. W. J . Simonsick (Dupont
Co., Philadelphia, PA) for useful discussions and the
K+IDS mass spectra.
Su p p or t in g In for m a t ion Ava ila b le: Full crystallo-
graphic data, bond lengths, and bond angles for 1b. This
material is available free of charge via the Internet at
http://pubs.acs.org.
OM0008530