New digermylalkenes and digermylalkynes: [1,3]-chlorine shifts in organogermanium chemistry?

Article abstract of DOI:10.1021/om061188j

Dimesitylfluoro(trichloromethyl)germane (1) has been synthesized from difluorodimesitylgermane, chloroform, and n-butyllithium. Addition of n-butyllithium to compound 1 gave the lithium carbenoid Mes₂(F)Ge- C(Li)Cl₂ (2), which behaves as a synthetic equivalent of the C-dichlorogermene Mes₂Ge=CCl₂ (5). Warming 2 to room temperature afforded the 1,2-digermylalkene Mes₂(F)Ge-CCl=CCl-Ge(Cl) Mes₂ (6) possibly by an unprecedented [1,3]-Cl shift from the transient germene Mes₂(F)Ge-CCl₂-CCl=GeMes₂ (8). Addition of tert-butyllithium to 6 gave bis(chlorogermyl)alkyne Mes ₂(Cl)Ge-C=C-Ge(Cl)Mes₂ (9) probably via a 3-chloro-1-germaallene/(chlorogermyl)alkyne rearrangement.

Full text of DOI:10.1021/om061188j

5136
Organometallics 2007, 26, 5136-5139
Articles
New Digermylalkenes and Digermylalkynes: [1,3]-Chlorine Shifts in
Organogermanium Chemistry?
Gabriela Nemes,† Jean Escudie´,‡ Ioan Silaghi-Dumitrescu,*,† Henri Ranaivonjatovo,*,‡
Luminita Silaghi-Dumitrescu,† and Heinz Gornitzka‡
Facultatea de Chimie si Inginerie Chimica, UniVersitatea Babes-Bolyai, 1 Kogalniceanu Street,
RO-400082, Cluj-Napoca, Romania, and He´te´rochimie Fondamentale et Applique´e, UMR CNRS 5069,
UniVersite´ Paul Sabatier, 118 Route de Narbonne, 31062 Toulouse Cedex 9, France
ReceiVed December 29, 2006
Dimesitylfluoro(trichloromethyl)germane (1) has been synthesized from difluorodimesitylgermane,
chloroform, and n-butyllithium. Addition of n-butyllithium to compound 1 gave the lithium carbenoid
Mes2(F)Ge-C(Li)Cl2 (2), which behaves as a synthetic equivalent of the C-dichlorogermene Mes2Ged
CCl2 (5). Warming 2 to room temperature afforded the 1,2-digermylalkene Mes2(F)Ge-CCldCCl-Ge-
(Cl)Mes2 (6) possibly by an unprecedented [1,3]-Cl shift from the transient germene Mes2(F)Ge-CCl2-
CCldGeMes2 (8). Addition of tert-butyllithium to 6 gave bis(chlorogermyl)alkyne Mes2(Cl)Ge-CtC-
Ge(Cl)Mes2 (9) probably via a 3-chloro-1-germaallene/(chlorogermyl)alkyne rearrangement.
Here we describe the preparation of the lithium compound
Mes2(F)Ge-C(Li)Cl2, a potential synthetic equivalent of the
C-dichloro compound Mes2GedCCl2, and its conversion on
warming to room temperature into the digermylalkene Mes2-
(F)Ge-CCldCCl-Ge(Cl)Mes2. The reaction of the latter with
tert-butyllithium afforded the digermylalkyne Mes2(Cl)Ge-Ct
C-Ge(Cl)Mes2. The mechanisms of these reactions and the
rearrangements involved are supported by B3LYP/6-31G(d)
calculations.
Introduction
Doubly bonded compounds of heavier group 14 elements
>MdC< (M ) Si, Ge, Sn) are important building blocks in
organometallic chemistry due to the more pronounced reactivity
of the >MdC< double bonds, compared to the corresponding
>CdC< bonds of their alkene analogues.1 The introduction of
one or two halogen substituents on the sp2 carbon atom should
greatly increase the synthetic utility of such compounds. The
C-dihalophosphaalkenes Mes*PdCX22 and arsaalkenes Mes*Asd
3
CX2 (Mes* ) 2,4,6-tri-tert-butylphenyl, X ) Br, Cl, I), for
Results and Discussion
instance, have proven to be powerful starting materials for the
synthesis of functionalized phospha(or arsa)alkenes,4 phos-
phaalkynes,5 and phospha(or arsa)allenes.6 In contrast to their
pnictogen counterparts, C-dihalometallaalkenes >MdCX2 de-
rivatives (M ) Si, Ge, Sn) are still unknown.
Addition of n-butyllithium to a mixture of difluorodimesi-
tylgermane7 and chloroform afforded the air- and moisture-stable
dimesitylfluoro(trichloromethyl)germane (1) (eq 1). The struc-
† Universitatea Babes-Bolyai.
‡ Universite´ Paul Sabatier.
(1) For reviews, see: (a) Power, P. P. Chem. ReV. 1999, 99, 3463. (b)
Okazaki, R.; West, R. AdV. Organomet. Chem. 1995, 39, 231. (c) West, R.
Polyhedron 2002, 21, 467. (d) Sekiguchi, A.; Lee, V. Ya. Chem. ReV. 2003,
103, 1429. (e) Tokitoh, N. Acc. Chem. Res. 2004, 37, 86. (f) Brook, A. G.;
Baines, K. M. AdV. Organomet. Chem. 1986, 25, 1. (g) Brook, A. G.; Brook,
M. A. AdV. Organomet. Chem. 1996, 39, 71. (h) Mu¨ller, T.; Ziche, W.;
Auner, N. In The Chemistry of Organic Silicon Compounds, Vol. 2;
Rappoport, Z., Apeloig, Y., Eds.; Wiley: Chichester, 1998; Chapter 16, p
857. (i) Barrau, J.; Escudie´, J.; Satge´, J. Chem. ReV. 1990, 90, 283. (j) Baines,
K; Stibbs, W. G. AdV. Organomet. Chem. 1996, 39, 275. (k) Escudie´, J.;
Ranaivonjatovo, H. AdV. Organomet. Chem. 1999, 44, 113.
(2) (a) Appel, R.; Casser, C.; Immenkeppel, M. Tetrahedron Lett. 1985,
26, 3551. (b) Goede, S. J.; Bickelhaupt, F. Chem. Ber. 1991, 124, 2677.
(3) Ramdane, H.; Ranaivonjatovo, H.; Escudie´, J.; Knouzi, N. Organo-
metallics 1996, 15, 2683.
ture of 1 was proven by its NMR spectra. The high-field shift
in the 19F NMR spectrum (δ 19F ) -96.1 ppm) lies in the
expected range for a fluorine atom bonded to a Mes2Ge-CR3
moiety (for example -105.2 ppm in Mes2(F)Ge-CH2CN8).
Moreover a 13C NMR signal at 94.96 ppm was observed for
the carbon atom bearing three chlorine atoms (comparable to δ
13C ) 77.7 ppm for CHCl3). The molecular peak was observed
in the mass spectrum of 1 (chemical ionization with NH3).
(4) Van Der Sluis, M.; Wit, J. B. M.; Bickelhaupt, F. Organometallics
1996, 15, 174.
(5) Yoshifuji, M.; Niitsu, T.; Inamoto, N. Chem. Lett. 1988, 1733.
(6) (a) Ranaivonjatovo, H.; Ramdane, H.; Gornitzka, H.; Escudie´, J.;
Satge´, J. Organometallics 1998, 17, 1631. (b) Bouslikhane, M.; Gornitzka,
H.; Escudie´, J.; Ranaivonjatovo, H.; Ramdane, H. J. Am. Chem. Soc. 2000,
122, 12880. (c) Bouslikhane, M.; Gornitzka, H.; Ranaivonjatovo, H.;
Escudie´, J. Organometallics 2002, 21, 1531.
(7) Rivie`re, P.; Rivie`re-Baudet, M.; Castel, A.; Desor, D.; Abdennadher,
C. Phosphorus, Sulfur, Silicon Relat. Elem. 1991, 61, 189.
(8) Lee, V. Ya.; Ranaivonjatovo, H.; Escudie´, J.; Satge´, J.; Dubourg,
A.; Declercq, J. P.; Egorov, M. P.; Nefedov, O. M. Organometallics 1998,
17, 1517.
10.1021/om061188j CCC: $37.00 © 2007 American Chemical Society
Publication on Web 09/13/2007

New Digermylalkenes and Digermylalkynes
Organometallics, Vol. 26, No. 21, 2007 5137
Scheme 1
Scheme 2
Figure 1. B3LYP/6-31G(d)-calculated energies along the [1,3]-
Cl shift reaction path in H2GedCCl-CCl2-GeH2F, 8H.
Treatment of fluorogermane 1 with tert-butyllithium at low
temperature afforded the lithium (fluorogermyl)carbenoid 2.
Quenching 2 with methanol gave the methoxygermane 3 by
further reaction of the initially produced fluorogermane 4 with
lithium methoxide (Scheme 1).
Formation of 3 by successive elimination of lithium fluoride
from 2 to give Mes2GedCCl2 5 followed by addition of
methanol to the double bond of 5 can be ruled out since warming
2 to room temperature in the absence of methanol did not give
either 5, its dimer, or a rearrangement product (vide infra).
However, since methoxygermane 3 is the anticipated product
of the reaction of 5 with methanol, lithium carbenoid 2 can be
considered as a synthetic equivalent of the still unknown
C-dichlorogermene 5.
mol-1),10 which suggests that this process might be facile in 8
as well. This chlorotropic migration affords finally the thermo-
dynamically favorable E-dichlorodigermylalkene 6.
That alkene 6 is favored over germene 8 could also be
expected by consideration of the bond energies involved: the
CdC π-bond energy (250 kJ mol-1) is greater than the GedC
π-bond (about 130 kJ mol-1),11 whereas CCl and GeCl bond
energies are not very different in magnitude (326 and 339 kJ
mol-1).
The structure of 6 in solution was deduced from its mass
and NMR spectra: two sets of signals were observed in the 1H
NMR spectrum for the nonequivalent Mes2Ge(Cl) and Mes2-
Ge(F) groups and one singlet and one doublet (coupling with
fluorine) at 147.53 and 146.34 ppm (2JCF ) 57 Hz), respectively,
for the ethylenic carbon atoms in the 13C NMR spectrum. The
structure of 6 in the solid state was unambiguously established
by a single-crystal X-ray diffraction study (Figure 2), which
showed it to be the trans isomer (Ge1C1C2Ge2 ) 160.94(19)°,
Cl3C1C2Cl4 ) 174.23(18)°), a finding that is again supported
by the calculated path of reaction shown in Figure 1. The bond
lengths and bond angles in 6 lie in the normal range expected
for such systems.12
(Chloroalkyl)germene/(Chlorogermyl)alkene Rearrange-
ment. Warming lithium compound 2 to room temperature
surprisingly afforded the 1,2-dichloro(chlorogermyl)(fluorog-
ermyl)ethene 6 in nearly quantitative yield (eq 2). The formation
of 6 can be reasonably explained by the selective â-elimination
of LiF from 7, leading to the transient germene Mes2(F)Ge-
CCl2-CCldGeMes2 8 (Scheme 2). Compound 7 could be
formed by an “eliminative dimerization” of two molecules of
carbenoid 2 (as Cl2(H)C-CCl(H)Li from Cl2(H)CLi9) or by
insertion of the carbene Mes2(F)Ge-CCl into the carbenoid 2.
Germene 8 then undergoes an unprecedented [1,3]-chlorine shift
(Scheme 2).
Germaallene/Germylalkyne Rearrangement. The reaction
of tert-butyllithium with compound 6 afforded bis(chlorodi-
mesitylgermyl)alkyne (9) as the sole product. The NMR
spectroscopic data are indicative of a symmetrical structure (two
singlets for the o- and p-Me groups of equivalent mesityl groups
and a single signal for the acetylenic carbon atoms at δ 13C )
114.12 ppm), as well as the absence of a fluorine atom (eq 3).
Unfortunately, attempts to trap any intermediate by 2,3-
dimethylbutadiene failed. This prompted us to gain insight into
the reaction pathway by theoretical studies. The mechanism of
the [1,3]-Cl shift from (chloroalkyl)germene 8 to (chloroger-
myl)alkene 6 was investigated by means of DFT B3LYP/6-
31G(d) calculations on the model systems 8H and 6H, in which
the bulky substituents on germanium have been replaced by
hydrogen atoms. The relative energies of 8H, 6H, and the
transition state relating them are given in Figure 1. The barrier
of this reaction (59 kJ mol-1) is contrastingly lower than that
calculated for the [1,3]-Cl shift in 3-chloro-1-propene (216 kJ
The preference for the lithium/chlorine exchange reaction to
take place at the carbon atom bearing the Mes2Ge(F) moiety
has been assessed by the B3LYP/6-31G(d) calculations on the
enthalpy changes of the isodesmic reactions in eq 4:
(10) Koch, R.; Wong, M. W.; Wentrup, C. J. Org. Chem. 1996, 61, 6809.
(11) Dobbs, K. D.; Hehre, W. J. Organometallics 1986, 5, 2057.
(12) Baines, K.; Stibbs, W. G. Coord. Chem. ReV. 1995, 145, 157.
(9) Ko¨brich, G; Merkle, H. R. Chem. Ber. 1966, 99, 1782.

5138 Organometallics, Vol. 26, No. 21, 2007
Nemes et al.
Figure 2. Molecular structure of 6 (thermal ellipsoids are shown
at 50% probability level). Selected bond distances (Å), bond angles
(°), and dihedral angles (°): Ge1C1 ) 1.988(3), Ge2C2 ) 1.987-
(3), C1C2 ) 1.335(5), C1Cl3 ) 1.749(3), C2Cl4 ) 1.756(3), Ge1F1
) 1.778(9), Ge2Cl2 ) 2.141(3), Ge1C3 ) 1.955(4), Ge1C12 )
1.961(3), Ge2C21 ) 1.957(3), Ge2C30 ) 1.931(3), Ge1C1C2 )
127.9(3), Cl3C1C2 ) 115.3(3), Ge1C1Cl3 ) 116.6(2), Ge2C2Cl4
) 116.3(2), GeC2C1 ) 127.9(3), Ge1C1C2Ge2 ) 160.94(19),
Cl3C1C2Cl4 ) 174.23(18).
Figure 3. B3LYP/6-31G(d)-calculated pathway of the [1,3]-Cl
migration in ClGeH2-CCldCdGeH2.
Allenes to alkynes rearrangements are well-known in carbon
chemistry13 but have been neither observed nor postulated in
germanium chemistry. Two stable germaallenes, Tip2GedCd
C(Ph)(t-Bu) (Tip ) 2,4,6-triisopropylphenyl)14 and Mes(Tbt)-
GedCdCR2 (Tbt ) 2,4,6-tris[bis(trimethylsilyl)methyl]phenyl,
CR2 ) fluorenylidene),15 were isolated by West14 and Tokitoh,15
but isomerization of these species to the corresponding germy-
lalkynes was not observed. The only examples of such a
rearrangement in group 14 element chemistry were reported by
Barton16 in a silaallene (migration of a hydrogen atom) and by
Ishikawa17 in the case of a nickel complex of a silaallene ([1,3]-
phenyl shift). Note that a reverse silylalkyne/silaallene rear-
rangement also has been reported by Ishikawa.18
H2FGe-C(Cl)dC(Cl)-GeClH2 +
CH3Li ) H2FGe-C(Li)dC(Cl)-GeClH2 + CH3Cl (4a)
∆H ) -170.35 kJ mol-1
H2FGe-C(Cl)dC(Cl)-GeClH2 +
CH3Li ) H2FGe-C(Cl)dC(Li)-GeClH2 + CH3Cl (4b)
∆H ) -148.72 kJ mol-1
Conclusion
The exclusive formation of bis(chlorogermyl)alkyne 9 rules
out the formation of the triple bond by elimination of lithium
chloride from alkene 10, which would have given the 1,2-
(chlorogermyl)(fluorogermyl)alkyne Mes2(F)Ge-CtC-Ge-
(Cl)Mes2.
[1,3]-Chlorine shifts in both transient germene Mes2(F)Ge-
CCl2-CCldGeMes2 and allene Mes2GedCdCCl-Ge(Cl)Mes2
account for the formation of the isolated E-dichlorodigermyla-
lkene and digermylalkyne, respectively. No precedent of such
rearrangements has been reported in germanium chemistry.
The formation of 9 likely involves the selective LiF â-elim-
ination from 10 to give the transient germaallene 11. A [1,3]-
chlorine shift then would lead to the observed bis(chlorogermyl)-
alkyne 9 (Scheme 3).
Experimental Part
All manipulations were carried out under Ar using standard
Schlenk techniques with solvents freshly distilled from sodium
benzophenone. H, 13C, and 19F NMR (external ref CF3COOH)
1
spectra were recorded in CDCl3 on Bruker AC 200 (1H, 200.1 MHz;
13C, 50.1 MHz; 19F, 188.30 MHz) and Bruker Avance 300 (13C,
75.46 MHz) instruments. 13C NMR signals were assigned by
Scheme 3
(13) (a) The Chemistry of Ketenes, Allenes and Related Compounds;
Patai, S., Ed.; Wiley: New York, 1980. (b) The Chemistry of Allenes;
Landor, S. R., Ed.: Academic Press: London, 1982. (c) Allenes in Organic
Synthesis; Schuster, H. F., Coppola, G. M., Eds.; Wiley: New York, 1984.
(14) Eichler, B. E.; Powell, D. R.; West, R. Organometallics 1998, 17,
2147.
(15) (a) Kishikawa, K.; Tokitoh, N.; Okazaki, R. Organometallics 1997,
16, 5127. (b) Tokitoh, N; Kishikawa, K.; Okazaki, R. Chem. Lett. 1998,
811.
(16) (a) Barton, T. J.; Burns, G. T.; Goure, W. F.; Wulff, W. D. J. Am.
Chem. Soc. 1982, 104, 1149. (b) Yeh, M.-H.; Linder, L.; Hoffman, D. K.;
Barton, T. J. J. Am. Chem. Soc. 1986, 108, 7849.
(17) (a) Ishikawa, M.; Ohshita, J.; Ito, Y. Organometallics 1986, 5, 1518.
(b) Ishikawa, M.; Nomura, Y.; Tozaki, E.; Kunai, A.; Ohshita, J. J.
Organomet. Chem. 1990, 399, 205.
(18) (a) Ishikawa, M.; Fuchikami, T.; Kumada, M. J. Am. Chem. Soc.
1979, 101, 1348. (b) Ishikawa, M.; Kovar, D.; Fuchikami, T.; Nishimura,
K.; Kumada, M.; Higuchi, T.; Miyamoto, S. J. Am. Chem. Soc. 1981, 103,
2324. (c) Ishikawa, M.; Nishimura, K.; Ochiai, H.; Kumada, M. J.
Organomet. Chem. 1982, 236, 7.
The barrier of the [1,3]-Cl shift from 11 to 9 estimated on
the models 11H and 9H (Figure 3) is slightly higher than that
of the similar rearrangement in H2FGe-CCl2-C(Cl)dGeH2.
ONIOM B3LYP/6-31G(d):PM3 calculations on 9 and 11 also
reveal a conspicuous difference in energy (170.71 kJ mol-1) in
favor of 9.

New Digermylalkenes and Digermylalkynes
Organometallics, Vol. 26, No. 21, 2007 5139
Attached Proton Test. Mass spectra were measured on a Hewlett-
Packard 5989 A spectrometer by EI at 70 eV, except that of
compound 1, which was measured on a NERMAG R10-10
spectrometer by CI (NH3). Melting points were determined on a
Leitz microscope heating stage 250.
Mes2(F)Ge-CCldCCl-Ge(Cl)Mes2, 6. A 6 mL amount of a
1.5 M hexane solution of t-BuLi (0.9 mmol) was added to a solution
of Mes2(F)Ge-CCl3 (1) (4.00 g, 8.84 mmol) in THF (50 mL)
cooled to -110 °C to form Mes2(F)Ge-C(Li)Cl2. The reaction
mixture was slowly warmed to room temperature within 2 h. After
filtration and removal of solvents in vacuo, 20 mL of Et2O was
added. Cooling to -20 °C gave 2.06 g (60%) of 6 as a crystalline
Molecular orbital calculations were performed at the B3LYP/
6-31G(d) level19-21 on the model compounds mentioned in the text.
In addition, full geometry optimization of 9 and 11 was carried
out by using an ONIOM B3LYP/6-311G(d):PM3 model22,23 (het-
eroatoms included in the high level, the organic radicals form the
lower level shell) by resorting to the Gaussian 98 system.24
Mes2(F)Ge-CCl3, 1. A mixture of Mes2GeF2 (4.00 g, 11.47
mmol) and CHCl3 (1.38 g, 1 equiv) in THF (50 mL) was cooled to
-110 °C, and 9 mL of a 1.6 M hexane solution of n-BuLi (14.4
mmol) was added. The reaction mixture was slowly warmed to
room temperature under magnetic stirring for 4 h; after removal of
LiF by filtration and of the solvents in vacuo, crystallization from
1
product (mp 207 °C). H NMR: δ 2.28 (s, 12H, o-Me), 2.35 (s,
12H, p-Me), 2.42 (s, 12H, o-Me), 6.86 (s, 8H). 13C NMR: δ 21.07
and 21.17 (p-Me), 23.10 (d, 4JFC ) 12 Hz, o-Me), 23.99 (s, o-Me),
2
129.31 and 129.74 (m-C), 131.75 (d, JFC ) 45 Hz, ipso-C
MesGeF), 133.80 (ipso-C MesGeCl), 140.15 and 140.51 (p-C),
143.13 and 143.34 (o-C), 146.34 (d, 2JFC ) 57 Hz, dCGeF), 147.53
(dCGeCl). 19F NMR: δ -101.5. MS: 772 (M, 5), 561 (M - F -
2Cl - Mes + 1, 7), 494 (M - 2MesH - HCl, 80), 331 (Mes2GeF,
100), 191 (MesGe - 2, 25), 120 (MesH, 95). Anal. Calcd for
C38H44Cl3FGe2: C, 59.17; H, 5.75. Found: C, 59.19; H 5.81.
1
pentane afforded 3.50 g (60%) of 1 (mp 147 °C). H NMR: δ
Mes2(Cl)Ge-CtC-Ge(Cl)Mes2, 9. To a solution of 6 (1.00
g, 1.30 mmol) in THF (10 mL) cooled to -110 °C was added 0.9
mL of a 1.5 M hexane solution of t-BuLi (1.35 mmol). The mixture
was slowly warmed to room temperature within 2 h. After filtration,
the solvents were removed in vacuo and 5 mL of pentane was
added. Cooling to -20 °C led to 0.73 g (79%) of 9 as a white
solid (mp 111 °C). 1H NMR: δ 2.26 (s, 12H, p-Me), 2.41 (s, 24H,
o-Me), 6.80 (s, 8H arom H). 13C NMR: δ 21.15 (p-Me), 24.04
(o-Me), 114.12 (CtC), 129.72 (m-C), 132.46 (ipso-C), 139.80 (p-
C), 142.86 (o-C). MS: 681 (M - Cl, 6), 371 (Mes2(Cl)Ge-CtC,
20), 347 (Mes2GeCl, 28), 335 (Mes2Ge-CtC - 1, 100), 191
(MesGe - 2, 25), 120 (MesH, 85). Anal. Calcd for C38H44Cl2Ge2:
C, 63.67; H, 6.19. Found: C, 63.37; H 6.08.
4
2.28 (s, 6H, p-Me), 2.53 (d, JHF ) 1.7 Hz, 12H, o-Me), 6.89 (s,
4H, arom H). 13C NMR: δ 21.18 (p-Me), 23.88 (d, 4JFC ) 3.5 Hz,
o-Me), 94.96 (CCl3), 129.64 (m-C), 131.04 (d, 2JFC ) 9.1 Hz, ipso-
C), 141.20 (p-C), 143.44 (o-C). 19F NMR: δ -96.1. MS: 429 (M
- F, 6), 331 (Mes2GeF, 100), 311 (Mes2Ge - 1, 30), 191 (MesGe
- 2, 35), 91 (PhMe - 1, 90). DCI: 483 (M + N2H7+, 21), 466 (M
+ NH4+, 76), 449 (M + H+, 31). Anal. Calcd for C19H22Cl3FGe:
C, 50.90; H, 4.95. Found: C, 51.10; H, 4.85.
Mes2(MeO)Ge-CHCl2, 3. To a solution of 1 (0.70 g, 1.56
mmol) in THF (10 mL) cooled to -110 °C was added 1 mL of a
1.7 M in hexane solution of t-BuLi (1.7 mmol). The reaction
mixture was stirred at -80 °C for 30 min. Methanol (in excess)
was added, and the reaction mixture was slowly warmed to room
temperature within 2 h. After filtration, the solution was concen-
trated in vacuo to remove the solvents. Cooling the crude product
in pentane to -20 °C gave 3 as a yellow, waxy product (0.53 g,
Crystal Data for 6. C38H44Cl3FGe2, M ) 771.26, monoclinic,
P21/c, a ) 8.447(1) Å, b ) 28.130(3) Å, c ) 15.094(1) Å, â )
95.896(2)°, V ) 3567.5(6) Å3, Z ) 4, T ) 193(2) K; 20 785
reflections (7328 independent, Rint ) 0.0483) were collected. Largest
electron density residue: 0.527 e Å-3, R1 (for I > 2σ(I)) ) 0.0442
and wR2 ) 0.0947 (all data) with R1 ) ∑||Fo| - |Fc||/∑|Fo| and
1
82%) in about 95% purity. H NMR: δ 2.31 (s, 6H, p-Me), 2.47
(s, 12H, o-Me), 3.54 (s, 3H, OMe), 6.11 (s, 1H, CH) 6.90 (s, 4H,
arom H). 13C NMR: δ 22.24 (p-Me), 25.03 (o-Me), 52.26 (OMe),
65.25 (CHCl2), 128.66 (m-C), 130.62 (ipso-C), 138.92 (p-C), 142.22
(o-C). MS: 426 (M, 5), 343 (M - CCl2H, 46), 311 (Mes2Ge - 1,
33), 191 (MesGe - 2, 18), 84 (CCl2H + 1, 98).
2
2 2 0.5
wR2 ) (∑w(Fo - Fc2)2/∑w(Fo ) )
.
All data for the structure represented in this paper were collected
at low temperatures using an oil-coated shock-cooled crystal on a
Bruker-AXS CCD 1000 diffractometer with Mo KR radiation (λ
) 0.71073 Å). The structure was solved by direct methods,25 and
all non hydrogen atoms were refined anisotropically using the least-
squares method on F2.26
(19) Becke, A. D. J. Chem. Phys. 1993, 98, 5648.
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Acknowledgment. We thank the CNCSIS (Romanian Coun-
cil for Scientific Research grant no. 6/45/AT), the CNRS, and
the Ministery of Foreign Affairs (AI Brancusi 2005 08581TK
(Fr)-C18015 (Ro)) for financial support.
Supporting Information Available: CIF files, total energies,
and optimized coordinates of the investigated systems. This material
is available free of charge via the Internet at http://pubs.acs.org.
OM061188J
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