Synthesis of bisgermavinylidene and its reaction with chalcogens

Article abstract of DOI:10.1021/om034071t

The lithium complex [HC(PPh₂=NSiMe₃)₂Li(THF)] (2) prepared by the reaction of BuⁿLi with bis(iminophosphorano)methane reacts with GeCl₂·dioxane in different stoichiometric ratios to afford [HC(PPh₂=NSiMe₃)₂GeCl] (3) and [(Me₃SiN=PPh₂)₂C=Ge→Ge=C (PPh₂=NSiMe₃)₂] (4), respectively. Bisgermavinylidene 4 can also be obtained by the reaction of 3 with [Ge{N(SiMe₃)₂}₂] or 2. Further reaction of 4 with Me₃NO afforded [(μ-N=Ph₂P)(Me₃-SiN=Ph₂P) C=Ge(OSiMe₃)]₂ (5), and direct reaction of elemental chalcogens (sulfur, selenium, and tellurium) with 4 afforded [(Me₃SiN=PPh₂)₂C=Ge(μ-E)]₂ [E = S (6), Se (7), and Te (8)]. X-ray structures of compounds 2-8 have been determined.

Full text of DOI:10.1021/om034071t

Organometallics 2003, 22, 4305-4311
4305
Syn th esis of Bisger m a vin ylid en e a n d Its Rea ction w ith
Ch a lcogen s
Wing-Por Leung,* Cheuk-Wai So, Zhong-Xia Wang, J in-Zhi Wang, and
Thomas C. W. Mak
Department of Chemistry, The Chinese University of Hong Kong, Shatin,
New Territories, Hong Kong, China
Received J uly 28, 2003
The lithium complex [HC(PPh2dNSiMe3)2Li(THF)] (2) prepared by the reaction of BunLi
with bis(iminophosphorano)methane reacts with GeCl2‚dioxane in different stoichiometric
ratios to afford [HC(PPh2dNSiMe3)2GeCl] (3) and [(Me3SiNdPPh2)2CdGefGedC(PPh2d
NSiMe3)2] (4), respectively. Bisgermavinylidene 4 can also be obtained by the reaction of 3
with [Ge{N(SiMe3)2}2] or 2. Further reaction of 4 with Me3NO afforded [(µ-NdPh2P)(Me3-
SiNdPh2P)CdGe(OSiMe3)]2 (5), and direct reaction of elemental chalcogens (sulfur, selenium,
and tellurium) with 4 afforded [(Me3SiNdPPh2)2CdGe(µ-E)]2 [E ) S (6), Se (7), and Te (8)].
X-ray structures of compounds 2-8 have been determined.
In tr od u ction
nylidene “:GedC(PPh2dNSiMe3)2”, which may serve as
a synthon for the direct synthesis of germaketene
analogues through the active lone pair at the germa-
nium center.
In this paper, we report the full details of the
preparation and characterization of [(Me3SiNdPPh2)2Cd
GefGedC(PPh2dNSiMe3)2] (4) and its reactivity with
chalcogens in order to prepare the germaketene ana-
logues.
Compounds containing a double bond between ger-
manium and carbon (>GedC<) have attracted much
attention in the past 15 years, and they have been the
focus of several reviews.1 It was found that the thermal
stability of the GedC bond is intrinsically low, and it
can undergo oligomerization readily.2 Nevertheless,
stable germenes R2GedCR′2 can be synthesized by
incorporating sterically bulky substituents at both
germanium and carbon.3 The low-valent germanium
analogues such as germavinylidenes (>CdGe:) are rare.
We have communicated the synthesis of bisgermavi-
Resu lts a n d Discu ssion
Syn t h esis of Bisger m a vin ylid en e [(Me 3SiNd
P P h 2)2CdGefGedC(P P h 2dNSiMe3)2] (4). Treat-
ment of bis(iminophosphorano)methane [(Me3SiNd
PPh2)2CH2] (1)6 with BunLi in THF afforded the
monomeric [HC(PPh2dNSiMe3)2Li‚THF] (2), which has
been reported earlier, but it has not been structurally
characterized.7 We have now determined the X-ray
structure of 2. The similar lithium complex [Li{HC-
(Cy2PdNSiMe3)2-κC,κN,κN′}(OEt2)] (Cy ) cyclohexyl)
prepared from the reaction of [(Me3SiNdPCy2)2CH2]
with excess MeLi has been reported.8
The reaction of 2 equiv of 2 with GeCl2‚dioxane for 2
days afforded bisgermavinylidene [(Me3SiNdPPh2)2Cd
GefGedC(PPh2dNSiMe3)2] (4) (Scheme 1). When the
reaction was quenched after 1 day, [HC(PPh2dNSiMe3)2-
GeCl] (3) can be isolated as the intermediate compound.
Compound 3 can be further dehydrochlorinated by 2 to
form bisgermavinylidene 4, if the reaction mixture was
kept for a further 24 h. It is suggested that compound
2 acts both as a ligand transfer reagent and as a base
for dehydrochlorination.
n yliden e
[(Me3SiNdP P h 2)2CdGefGedC(P P h 2d
NSiMe3)2] (4).4 We have also reported the synthesis of
some group 14 ketone analogues R2MdE from the direct
reaction of group 14 carbene analogues MR2 (R ) CH-
(SiMe3)C9H6N-8 or CPh(SiMe3)C5H4N-2; M ) Ge or Sn)
with corresponding elemental chalcogens.5 Recently, we
were interested in the synthesis of compounds contain-
ing a >CdGedE moiety, as they may be considered as
germaketene analogues, which are also scarcely found.
Their unusual structures and possibly the unknown
reactivity have attracted our interest. We anticipated
that the bisgermavinylidene 4 is potentially a source
for the reactive monomeric intermediate germavi-
(1) Selected recent reviews and examples of germenes: (a) Barrau,
J .; Escudie´, J .; Satge´, J . Chem. Rev. 1990, 90, 283. (b) Driess, M.;
Gru¨tzmacher, H. Angew. Chem., Int. Ed. Engl. 1996, 35, 828. (c)
Escudie´, J .; Ranaivonjatovo, H. Adv. Organomet. Chem. 1999, 44, 113.
(d) Couret, C.; Escudie´, J .; Satge´, J .; Lazraq, M. J . Am. Chem. Soc.
1987, 109, 4411. (e) Anselme, G.; Escudie´, J .; Couret, C.; Satge´, J . J .
Organomet. Chem. 1991, 403, 93. (f) Lazraq, M.; Couret, C.; Escudie´,
J .; Satge´, J . Polyhedron 1991, 10, 1153.
(2) Bravo-Zhivotovskii, D.; Zharov, I.; Kapon, M.; Apeloig, Y. J .
Chem. Soc., Chem. Commun. 1995, 1625.
Bisgermavinylidene
4 can also be synthesized
(3) (a) Meyer, H.; Baum, G.; Massa, W.; Berndt, A. Angew. Chem.,
Int. Ed. Engl. 1987, 26, 798. (b) Lazraq, M.; Escudie´, J .; Couret, C.;
Satge´, J .; Dra¨ger, M.; Dammel, R. Angew. Chem., Int. Ed. Engl. 1988,
27, 828. (c) Couret, C.; Escudie´, J .; Delpon-Lacaze, G.; Satge´, J .
Organometallics 1992, 11, 3176.
(4) Leung, W.-P.; Wang, Z.-X.; Li, H.-W.; Mak, T. C. W. Angew.
Chem., Int. Ed. 2001, 40, 2501.
stepwisely by the reaction of [Ge{N(SiMe3)2}2] with[HC-
(PPh2dNSiMe3)2GeCl] (3), which was prepared sepa-
(6) Mu¨ller, A.; Mo¨hlen, M.; Neumu¨ller, B.; Faza, N.; Massa, W.;
Dehnicke, K. Z. Anorg. Allg. Chem. 1999, 625, 1748.
(7) Ong, C. M.; Stephan, D. W. J . Am. Chem. Soc. 1999, 121, 2939.
(8) Babu, R. P. K.; Aparna, K.; McDonald, R.; Cavell, R. G.
Organometallics 2001, 20, 1451.
(5) Leung, W.-P.; Kwok, W.-H.; Zhou, Z.-Y.; Mak, T. C. W. Organo-
metallics 2000, 19, 296.
10.1021/om034071t CCC: $25.00 © 2003 American Chemical Society
Publication on Web 09/19/2003

4306 Organometallics, Vol. 22, No. 21, 2003
Leung et al.
Sch em e 1
Sch em e 2
Sch em e 3
rately by the reaction of 1 equiv of 2 with GeCl2‚dioxane
moiety is probably due to the reactive GedO bond. Some
previous attempts to generate >GedO species from
germylenes, which led to the formation of germain-
danol,11 oxo-bridged dimer [{(Me3Si)2N}2Ge(µ-O)]2,12 or
gem-dihydroxy compound [(2,6-Mes2H3C6)2Ge(OH)2],13
have been reported in the literature.
in Et2O. It is proposed that the ligand transfer inter-
mediate
[Ge{CH(PPh2dNSiMe3)2}{N(SiMe3)2}]
formed underwent dehydrochlorination and deamina-
tion with 3 to form bisgermavinylidene 4 (Scheme 2).
In contrast, the reaction of 3 with MgBun and AlMe3
2
in toluene at room temperature gave the known bis-
(iminophosphorano)methanide complexes [HC(PPh 2d
NSiMe3)2Mg(µ-Cl)]2 and [HC(PPh2dNSiMe3)2AlMe2],
respectively.9,10
The reaction of 4 with stoichiometric amounts of
elemental chalcogens in THF afforded chalcogen-bridged
dimers of germaketene analogues [(Me3SiNdPPh2)2Cd
Ge(µ-E)]2 [E ) S (6), Se (7), and Te (8)], respectively
(Scheme 4). Compounds 6-8 were isolated as colorless,
yellow, and red crystalline solids, respectively. The
unsuccessful isolation of compounds with terminal
germaketene moieties >CdGedE could be due to the
prolonged and more polar >CdGedE skeleton as com-
pared to >CdGedO, which is more susceptible to
dimerize at the chalcogen end and cannot be stabilized
kinetically by the ligand. Similar results have been
found for the synthesis of germaketone analogues in the
Rea ction of Bisger m a vin ylid en e w ith Ch a lco-
gen s. We have attempted to prepare the germaketene
analogue containing a terminal >CdGedO moiety by
the reaction of bisgermavinylidene 4 with 2 equiv of Me3-
NO in toluene. However, the product obtained was [(µ-
NdPh2P)(Me3SiNdPh2P)CdGe(OSiMe3)]2 (5) isolated as
a pale yellow crystalline solid (Scheme 3). It is proposed
that the intermediate compound bearing a >CdGedO
moiety underwent an insertion of the GeO unit into the
N-SiMe3 bond of the imino group. The unsuccessful
isolation of the compound with a terminal >CdGedO
(11) J utzi, P.; Schmidt, H.; Neumann, B.; Stammler, H.-G. Orga-
nometallics 1996, 15, 741.
(12) Ellis, D.; Hitchcock, P. B.; Lappert, M. F. J . Chem. Soc., Dalton
Trans. 1992, 3397.
(13) Pu, L.; Hardman, N. J .; Power, P. P. Organometallics 2001,
20, 5105.
(9) Aparna, K.; McDonald, R.; Ferguson, M.; Cavell, R. G. Organo-
metallics 1999, 18, 4241.
(10) Wei, P.; Stephan, D. W. Organometallics 2003, 22, 601.

Synthesis of Bisgermavinylidene
Organometallics, Vol. 22, No. 21, 2003 4307
Sch em e 4
reaction of germylenes with chalcogens, where chalco-
gen-bridged dimers were formed.14 Compounds 7 and 8
are light sensitive, as they turned black when exposed
to light. Therefore, the preparations of 7 and 8 were
carried out with the exclusion of light.
Sp ectr oscop ic P r op er ties of Com p ou n d s. The 1H
and 13C NMR spectra of 2 displayed one set of signals
due to the bis(iminophosphorano)methanide ligand and
THF, which is different from the unsolvated compound
reported by Stephan and co-workers.7
The 1H NMR spectrum of 3 displayed one singlet
signal for the SiMe3 group and a triplet at δ 3.50 ppm
(J P-H ) 12 Hz) for the methine proton on the P-C-P
backbone with coupling to two equivalent phosphorus
nuclei. The data indicate considerable delocalization
throughout the N-P-C-P-N backbone of the ligand,
consistent with the solid-state structure of 3. This is also
consistent with a singlet at δ 13.97 ppm in the 31P NMR
spectrum. The 13C NMR spectrum of 3 is normal and
F igu r e 1. Crystal structure of 2 with atomic numbering
scheme.
1
consistent with the H NMR spectrum.
angles (deg) of 2 are listed in Table 2. The four-
coordinated Li(1) is bonded to the methanide carbon
atom C(55), two imino nitrogen atoms from the
ligand, and O(1) from the THF to form two strained
four-membered metallacycles sharing the Li(1)-C(55)
edge. The Li(1)-C(55) bond distance of 2.622(9) Å in 2
is similar to that of 2.633(7) Å in [Li{HC(Cy2Pd
NSiMe3)2-κC,κN,κN′}(OEt2)].8 The Li(1)-N distances of
1.980(9) and 2.017(9) Å in 2 are comparable to those of
2.033(6) and 2.012(7) Å in [Li{HC(Cy2PdNSiMe3)2-
κC,κN,κN′}(OEt2)].8 The P-N distances of 1.572(4) and
1.575(3) Å and the C-P bonds of 1.717(4) and 1.722(4)
Å are different from those of [(Me3SiNdPPh2)2CH2] (1)
(P-N ) 1.536(2) Å; C-P ) 1.825(1) Å).6 These suggest
considerable delocalization throughout the N-P-C-
P-N ligand backbone.
Compound 3 is a monomeric heteroleptic germylene.
The solid-state structure of 3 is shown in Figure 2.
Selected bond distances (Å) and angles (deg) of 3 are
listed in Table 2. The bis(iminophosphorano)methanide
ligand is bonded in a N,N′-chelate fashion to the
germanium center and adopts a trigonal pyramidal
geometry. The sum of bond angles at the metal center
is 299.97°, which deviates significantly from the tetra-
coordinated germylene.16 This is consistent with a
stereoactive lone pair at the germanium center. The
distance between the methanide carbon and germanium
of 3.339 Å is significantly longer than the Li-C bond
distance of 2.622(9) Å in 2 and the Mg-C bond distance
of 2.460(8) Å in [HC(PPh2dNSiMe3)2Mg(µ-Cl)]2,10 sug-
gesting no interaction between germanium and meth-
anide carbon. The bond distances of Ge-N, P-N, and
1
The H and 13C NMR spectra of 5 are normal. The
31P NMR spectrum of 5 displayed two signals at δ 18.66
and 44.61 ppm due to two different phosphorus environ-
ments, consistent with the solid-state structure.
The 1H and 13C NMR spectra of 6-8 showed a similar
pattern and displayed one set of signals due to the bis-
(iminophosphorano)methandiide ligand. The 31P NMR
spectra of 6-8 displayed two sharp singlets [δ 10.69,
57.52 (6); δ 13.97, 60.80 (7); δ 11.78, 58.97 ppm (8)] due
to two different phosphorus environments, consistent
with the solid-state structures. It is suggested that the
coordination of the imino groups to the germanium
centers in 6-8 is nonfluxional in solution. The 77Se
NMR spectrum of 7 displayed a singlet at δ 860.88 ppm,
which showed a downfield shift as compared with the
signal at δ -476.0 ppm for [Ge{(NSiMe3)2}2(µ-Se)]2,14d
but similar to that of δ 940 ppm in [(Tbt)(Mes)GedSe].15
It is suggested that 7 may exist as a monomer in
solution. The 125Te NMR spectrum of 8 displayed a
singlet at δ 1025.53, which is comparable to the signal
of δ 1184 ppm in [Ge{(NSiMe3)2}2(µ-Te)]2.14d The FAB-
mass spectrum of compound 5 did not show the parent
peak. The FAB-mass spectra of compounds 6-8 dis-
played the peak due to [M/2 + H]+, suggesting that 6-8
may exist as monomeric species in the vapor phase.
X-r a y Str u ctu r es. The solid-state structure of 2 is
shown in Figure 1. Selected bond distances (Å) and
(14) (a) Hitchcock, P. B.; J asim, H. A.; Kelly, R. E.; Lappert, M. F.
J . Chem. Soc., Chem. Commun. 1985, 1776. (b) Wojnowska, M.;
Noltemeyer, M.; Fu¨llgrabe, H.-J .; Meller, A. J . Organomet. Chem. 1982,
228, 229. (c) Hitchcock, P. B.; J asim, H. A.; Lappert, M. F.; Leung,
W.-P.; Rai, A. K.; Taylor, R. E. Polyhedron 1991, 10, 1203. (d)
Hitchcock, P. B.; J ang, E.; Lappert, M. F. J . Chem. Soc., Dalton Trans.
1995, 3179.
(15) Matsumoto, T.; Tokitoh, N.; Okazaki, R. Angew. Chem., Int. Ed.
Engl. 1994, 33, 2316.
(16) Leung, W.-P., Kwok, W.-H.; Weng, L.-H.; Law, L. T. C.; Zhou,
Z.-Y.; Mak, T. C. W. J . Chem. Soc., Dalton Trans. 1997, 22, 4301.

4308 Organometallics, Vol. 22, No. 21, 2003
Ta ble 1. Cr ysta llogr a p h ic Da ta for Com p ou n d s 2, 3, a n d 5 a n d 6-8
Leung et al.
2
3
5
formula
fw
C
35H47LiN2OP2Si2
C
31H39ClGeN2P2Si2
C62H76N4P4O2Si4Ge2
1290.69
636.81
665.80
color
colorless
triclinic
P1h
11.028(2)
11.311(2)
16.174(3)
72.96(3)
88.60(3)
82.62(3)
1912.7(7)
2
1.106
pale yellow
triclinic
P1h
pale yellow
monoclinic
C2/c
cryst syst
space group
a (Å)
b (Å)
c (Å)
12.021(4)
15.050(4)
20.647(6)
90.000(6)
90.000(6)
66.460(4)
3424.6(17)
4
26.24(3)
13.746(7)
20.021(8)
90
107.08(9)
90
6903(9)
4
1.242
1.075
R (deg)
â (deg)
γ (deg)
V (Å3)
Z
dcalcd (g cm-3
)
1.291
1.158
1384
µ (mm-1
F(000)
)
0.203
680
2688
cryst size (mm)
2θ range (deg)
index range
0.60 × 0.50 × 0.40
2.27-25.00
-13 e h e 13,
-13 e k e 0,
-19 e l e 18
7100
1.30 × 0.79 × 0.78
0.99-28.28
-10 e h e 15,
-18 e k e 19,
-27 e l e 27
23 036
0.32 × 0.15 × 0.15
1.62-28.11
-25 e h e 34,
-18 e k e 18,
-26 e l e 19
23 200
no. of reflns collected
no. of indep reflns
6728
16 172
8352
R1, wR2 (I > 2(σ)I)
0.0647, 0.1762
0.1467, 0.2126
1.056
0.1010, 0.2552
0.1189, 0.2723
1.005
0.0649, 0.1198
0.2073, 0.1625
0.782
R1, wR2 (all data)
goodness of fit, F2
no. of data/restraints/params
6728/1/388
0.402 to -0.340
16172/0/703
3.046 to -0.808
8352/0/353
0.876 to -0.523
largest diff peaks, e Å-3
6
7
8
formula
fw
C
62H76N4Ge2P4S2Si2
C
62H76N4Ge2P4Se2Si2
C62H76N4Ge2P4Si2Te2
1513.89
1322.81
1418.62
color
white
yellow
red
cryst syst
space group
a (Å)
b (Å)
c (Å)
triclinic
P1h
monoclinic
P21/c
11.8491(14)
16.902(2)
17.737(2)
90
105.057(3)
90
3430.3(7)
2
triclinic
P1h
10.1970(6)
11.5672(7)
15.9241(9)
79.1130(10)
88.5170(10)
69.3700(10)
1724.49(18)
1
10.4130(5)
11.6373(6)
15.0654(7)
103.7030(10)
90.9820(10)
101.5030(10)
1734.05(15)
1
R (deg)
â (deg)
γ (deg)
V (Å3)
Z
dcalcd (g cm-3
)
1.274
1.133
688
1.373
2.140
1452
1.450
1.891
760
µ (mm-1
F(000)
)
cryst size (mm)
2θ range (deg)
index range
0.50 × 0.17 × 0.17
1.30-28.02
-13 e h e 13,
-15 e k e 11,
-20 e l e 21
11 921
1.00 × 0.18 × 0.16
1.69-28.07
-15 e h e 15,
-17 e k e 22,
-23 e l e 20
22 966
0.45 × 0.26 × 0.24
1.84-28.00
-13 e h e 13,
-9 e k e 15,
-19 e l e 15
11 765
no. of reflns collected
no. of indep reflns
8215
8299
8186
R1, wR2 (I > 2(σ)I)
0.0616, 0.1336
0.1510, 0.1682
0.879
0.0667, 0.1555
0.1357, 0.1787
0.901
0.0364, 0.0789
0.0594, 0.0859
0.904
R1, wR2 (all data)
goodness of fit, F2
no. of data/restraints/params
8215/0/352
0.643 to -0.570
8299/7/397
1.444 to -1.077
8186/0/352
0.837 to -0.504
largest diff peaks, e Å-3
C-P are similar. This shows considerable delocalization
throughout the N-P-C-P-N backbone of the ligand.
The Ge-N distances of 1.983(4) and 2.002(4) Å in 3 are
similar to those distances reported for typical Ge-N
single bond distances ranging from 1.910 to 2.042 Å.17
The Ge-Cl bond distance of 2.334(2) Å in 3 is longer
than that of 2.203(10) Å in [Ge(C6H3-2,6-Trip2)Cl]18 and
2.295(12) Å in [{HC(CMeNAr)2}GeCl].19
The molecular structure of 5 is shown in Figure 3.
Selected bond distances (Å) and angles (deg) of 5 are
listed in Table 2. Compound 5 is comprised of two
germenes joined by the “Ph2PdN” bridges to form an
eight-membered heterocyclic ring. The geometry
around the germanium atom is tetrahedral. The Ge-C
distance of 1.915(5) Å is slightly longer than those of
1.905(8) and 1.908(7) Å in 4. The Ge-O distance of
1.759(4) Å is relatively shorter when compared with the
Ge-O bond distance of 1.792 Å in [(2,6-Mes2H3C6)2Ge-
(OH)2],13 1.805 Å in [{(Me3Si)2N}2Ge(µ-O)]2,12 and the
sum of the covalent radii of germanium (1.22 Å) and
oxygen (0.66 Å).
(17) Foley, S. R.; Zhou, Y.; Yap, G. A. P.; Richeson, D. S. Inorg. Chem.
2000, 39, 924.
(18) Pu, L.; Olmstead, M. M.; Power, P. P.; Berthold, S. Organome-
tallics 1998, 17, 5602.
(19) Ding, Y.; Roesky, H. W.; Noltemeyer, M.; Schmidt, H.-G.; Power,
P. P. Organometallics 2001, 20, 1190.

Synthesis of Bisgermavinylidene
Organometallics, Vol. 22, No. 21, 2003 4309
F igu r e 3. Crystal structure of 5 with atomic numbering
scheme.
F igu r e 2. Crystal structure of 3 with atomic numbering
scheme.
Ta ble 2. Selected Bon d Dista n ces (Å) a n d An gles
(d eg) for Com p ou n d s 2, 3, a n d 5
[HC(PPh2dNSiMe3)2Li.THF] (2)
Li(1)-O(1)
Li(1)-C(55)
Li(1)-N(1)
Li(1)-N(2)
1.892(10) P(1)-N(1)
1.572(4)
1.575(3)
1.722(4)
1.717(4)
2.622(9)
1.980(9)
2.017(9)
P(2)-N(2)
P(1)-C(55)
P(2)-C(55)
O(1)-Li(1)-N(1)
O(1)-Li(1)-N(2)
122.2(5)
122.8(5)
N(1)-P(1)-C(55) 113.51(19)
N(2)-P(2)-C(55) 113.19(18)
P(1)-C(55)-Li(1) 74.3(2)
P(2)-C(55)-Li(1) 74.8(2)
N(1)-Li(1)-C(55) 72.1(3)
N(2)-Li(1)-C(55) 71.3(3)
F igu r e 4. Crystal structure of 8 with atomic numbering
scheme.
Li(1)-N(1)-P(1)
Li(1)-N(2)-P(2)
99.2(3)
98.3(3)
P(1)-C(55)-P(2)
130.3(2)
Ta ble 3. Selected Bon d Dista n ces (Å) a n d An gles
(d eg) for Com p ou n d s 6-8
[HC(PPh2dNSiMe3)2GeCl] (3)
Ge(1)-Cl(1)
Ge(1)-N(1)
Ge(1)-N(2)
2.334(2)
1.983(4)
2.002(4)
P(1)-N(1)
P(2)-N(2)
C(1)-P(1)
C(1)-P(2)
1.640(4)
1.637(4)
1.719(4)
1.700(4)
[(Me3SiNdPPh2)2CdGe(µ-E)]2
E ) S (6)
E ) Se (7)
E ) Te (8)
Ge(1)-E(1)
Ge(1)-E(1A)
Ge(1)-C(1)
P(1)-N(1)
P(2)-N(2)
Ge(1)-N(2)
P(1)-C(1)
P(2)-C(1)
2.230(2)
2.236(2)
1.875(5)
1.552(5)
1.645(4)
1.895(4)
1.748(5)
1.713(5)
2.357(4)
2.370(4)
1.873(2)
1.531(2)
1.655(2)
1.911(2)
1.744(2)
1.701(2)
2.585(4)
2.577(4)
1.912(3)
1.560(3)
1.664(3)
1.938(2)
1.735(3)
1.721(3)
N(1)-Ge(1)-N(2) 102.52(15) Ge(1)-N(1)-P(1) 120.0(2)
Cl(1)-Ge(1)-N(1) 99.41(12)
Cl(1)-Ge(1)-N(2) 98.04(11)
N(2)-P(2)-C(1)
N(1)-P(1)-C(1)
113.58(19)
114.2(2)
119.2(2)
Ge(1)-N(2)-P(2)
120.54(19) P(1)-C(1)-P(2)
[(µ-NdPh2P)(Me3SiNdPh2P)CdGe(OSiMe3)]2 (5)
C(1A)-Ge
Ge(1)-O(1)
O(1)-Si(1)
C(1A)-P(1)
C(1)-P(2)
1.915(5)
1.759(4)
1.633(4)
1.720(6)
1.716(6)
P(2)-N(2)
Ge(1)-N(2)
P(1)-N(1)
N(1)-Ge(1)
1.574(5)
1.745(5)
1.642(4)
1.956(5)
Ge(1)-E(1)-Ge(1A)
E(1)-Ge(1)-E(1A)
N(2)-Ge(1)-C(1)
Ge(1)-C(1)-P(2)
C(1)-P(2)-N(2)
P(2)-N(2)-Ge(1)
P(1)-C(1)-P(2)
84.67(5)
95.33(5)
82.1(2)
90.7(2)
95.0(2)
92.1(2)
121.9(3)
83.73(1)
96.28(1)
81.53(8)
91.74(10)
94.81(10)
91.89(8)
126.95(13)
81.42(1)
98.58(1)
81.93(12)
90.32(14)
96.43(13)
91.18(12)
124.71(17)
O(1)-Ge(1)-C(1A)
O(1)-Ge(1)-N(2)
P(2)-N(2)-Ge(1)
112.0(2)
108.3(2)
131.0(3)
P(2)-C(1)-P(1A)
N(1)-P(1)-C(1A)
133.4(3)
97.4(2)
Compounds 6-8 are isostructural and comprised of
the chalcogen-bridged germaketene dimers. The molec-
ular structure of 8 is shown in Figure 4. Selected bond
distances (Å) and angles (deg) of 6-8 are listed in Table
3. The Ge-C(1) bond distances of 1.875(5) Å in 6 and
1.873(2) Å in 7 are shorter than those of 1.905(8) and
1.908(7) Å in 4. The Ge-C(1) distance of 1.912(3) Å in
8 is slightly longer compared with those of 1.905(8) and
1.908(7) Å in 4. The average germanium-chalcogen
distances [2.233 Å (6), 2.364 Å (7), and 2.581 Å (8)]
increase with the covalent radii of chalcogens. One of
the imino groups of the ligand in 6-8 coordinates to
the germanium center, the others remaining uncoordi-
nated. The differences in the P-N bond distances
[1.552(5), 1.645(4) Å (6); 1.531(2), 1.655(2) Å (7); and
1.560(3), 1.664(3) Å (8)] suggest the delocalization of
π-electrons resulted from the conjugation of PdN and
CdGe double bonds in germavinylidene.
The Ge-S distances of 2.230(2) and 2.236(2) Å in 6
are longer than the GedS bond distance of 2.049(3) Å

4310 Organometallics, Vol. 22, No. 21, 2003
Leung et al.
reaction was stirred for 2 days. The volatiles were removed
under reduced pressure, and the residue was extracted with
hexane/Et2O, 1:1. After filtration and concentration of the
filtrate, compound 4 was obtained as orange-red crystals.
Yield: 0.63 g (79%).
Method B: A solution of 2 (1.16 g, 1.82 mmol) in Et2O (30
mL) was added slowly to a stirred solution of GeCl2‚dioxane
(0.21 g, 0.91 mmol) in Et2O (30 mL) at -90 °C. The yellow
suspension was raised to ambient temperature and stirred for
2 days. The precipitate was filtered. Hexane was added to the
filtrate and concentrated under reduced pressure. 4 was
obtained as orange-red crystals. Yield: 0.24 g (42%).
in [Tbt(Tip)GedS], but similar to those distances re-
ported for typical Ge-S single bonds (2.17-2.25 Å).20
The Ge-Se distances of 2.357(4) and 2.370(4) Å in 7 are
in the range 2.337-2.421 Å for some Ge-Se single
bonds reported, but slightly shorter than the Ge-Se
distance of 2.426(2) Å in [{CPh(SiMe3)2C5H4N-2}2Ged
Se].5 The Ge-Te bond distances of 2.585(4) and 2.577(4)
Å in 8 are slightly shorter than that in alkylidene-
telluragermirane (2.591(3) Å)21 and [Ge{N(SiMe3)2}(µ-
Te)]2 (2.595(2), 2.596(2) Å).14d
[(µ-NdP h 2P )(Me3SiNdP h 2P )CdGe(OSiMe3)]2 (5). A so-
lution of 4 (0.70 g, 0.55 mmol) in toluene (30 mL) was added
to Me3NO (0.095 g, 1.27 mmol) in toluene (30 mL) at -90 °C
with stirring. The reaction mixture faded gradually when
raised to ambient temperature. The pale yellow solution was
stirred at room temperature for 17 h. The volatiles were
removed under reduced pressure, and the residue was ex-
tracted with Et2O. It was filtered and concentrated, yielding
pale yellow crystals of 5. Yield: 0.33 g (46%). Mp: 196 °C (dec).
Anal. Found: C, 57.27; H, 5.73; N, 4.03. Calcd for C62H76N4P4O2-
Exp er im en ta l Section
Gen er a l P r oced u r es. All manipulations were carried out
under an inert atmosphere of dinitrogen gas by standard
Schlenk techniques. Solvents were dried over and distilled
from CaH2 (hexane) and/or Na (Et2O, toluene, and THF).
Sulfur, selenium, and tellurium powders were purchased from
Aldrich Chemicals and used without further purification.
GeCl2‚dioxane22 and [Ge{N(SiMe3)2}2]23 were prepared by
reported procedures. The 1H, 13C, 31P, 77Se, and 125Te NMR
spectra were recorded on Bru¨ker WM-300 or Varian 400
spectrometers. The NMR spectra were recorded in benzene-
d6 or THF-d8, and the chemical shifts δ are relative to SiMe4,
85% H3PO4, Ph2Se2, and Me2Te2 for 1H, 13C, 31P, 77Se, and
125Te NMR, respectively.
1
Si4Ge2: C, 57.69; H, 5.93; N, 4.34. H NMR (C6D6): δ -0.02
(s, 18H, SiMe3), 0.71 (s, 18H, OSiMe3), 6.51-8.73 (m, 40H, Ph).
13C{1H} NMR (C6D6): δ 2.29 (SiMe3), 3.76 (OSiMe3), 127.03
1
(m, Ph), 129.36 (m, Ph), 130.95 (d, J P-C ) 60.6 Hz, p-Ph′),
1
132.21 (d, J P-C ) 45.6 Hz, m-Ph′), 133.18 (s, o-Ph′), 133.40
1
(d, J P-C ) 42.9 Hz, ipso-Ph′). 31P{1H} NMR (C6D6): δ 18.66,
[HC(P P h 2dNSiMe3)2Li‚THF ] (2). BunLi (6.3 mL, 10.11
mmol, 1.6 M solution in n-hexane) was added slowly to the
solution of [(Me3SiNdPPh2)2CH2] (5.65 g, 10.11 mmol) in THF
(60 mL) at -90 °C. The brown suspension was raised to
ambient temperature and stirred overnight. Volatiles were
removed under reduced pressure, and the residue was ex-
tracted by Et2O. The precipitate was filtered. Hexane was
added to the filtrate and concentrated under reduced pressure.
Compound 2 was obtained as pale yellow crystals. Yield: 4.52
g (70%). Mp: 128-131 °C. Anal. Found: C, 65.68; H, 7.57; N,
4.49. Calcd for C35H47N2LiOP2Si2: C, 66.01; H, 7.44; N, 4.40.
1H NMR (C6D6): δ 0.22 (s, 18H, SiMe3), 1.22-1.26 (m, 4H,
THF), 1.67 (t, J P-H ) 2.7 Hz, 1H, PC(H)P), 3.61-3.65 (m, 4H,
THF), 7.02-7.08 (m, 12H, Ph), 7.74-7.81 (m, 8H, Ph). 13C-
44.61.
[(Me3SiNdP P h 2)2CdGe(µ-S)]2 (6). A solution of 4 (0.34 g,
0.27 mmol) in THF (30 mL) was added dropwise to the
colorless solution of powdered sulfur (0.017 g, 0.53 mmol) in
THF (30 mL) at 0 °C with stirring. The resultant yellow
solution was raised to room temperature and stirred for 36 h.
After filtration and concentration of the filtrate, compound 6
was obtained as white crystals. Yield: 0.11 g (30%). Mp: 175-
176 °C. Anal. Found: C, 56.16; H, 5.80; N, 4.05. Calcd for
C
62H76N4Ge2P4S2Si2: C, 56.29; H, 5.79; N, 4.24. 1H NMR (THF-
d8): δ -0.46 (s, 18H, SiMe3), -0.32 (s, 18H, SiMe3), 7.17-7.40
(m, 24H, Ph), 7.41-7.44 (m, 4H, Ph), 7.61-7.72 (m, 8H, Ph),
7.80-7.88 (m, 4H, Ph). 13C{1H} NMR (THF-d8): δ 2.16, 4.14
1
{1H} NMR (C6D6): δ 4.35 (SiMe3), 23.56 (t, J P-C ) 128.8 Hz,
2
(SiMe3), 128.20 (d,1J P-C ) 48.3 Hz, m-Ph), 128.58 (t, J P-C
)
24.0 Hz, o-Ph), 128.87 (d, 1J P-C ) 50.4 Hz, ipso-Ph), 130.08 (s,
PCP), 25.31, 68.66 (THF), 127.77 (s, p-Ph), 129.23 (s, m-Ph),
2
1
1
131.37 (t, J P-C ) 5.2 Hz, o-Ph), 142.08 (d, J P-C ) 95.5 Hz,
p-Ph), 131.15 (s, p-Ph′), 132.32 (s, m-Ph′), 132.59 (d, J P-C
)
ipso-Ph). 31P{1H} NMR (C6D6): δ 29.42.
67.2 Hz, o-Ph′), 133.71 (d, J P-C ) 46.2 Hz, ipso-Ph′). 31P{1H}
NMR (THF-d8): δ 10.69, 57.52. FAB-MS: m/z found 663.1040;
calcd for C31H38N2GeP2SSi 663.1054 ([M/2 + H]+).
1
[HC(P P h 2dNSiMe3)2GeCl] (3).
A solution of [HC-
(PPh2dNSiMe3)2Li‚THF] (2) (0.91 g, 1.43 mmol) in Et2O (20
mL) was added slowly to the solution of GeCl2‚dioxane (0.33
g, 1.43 mmol) in Et2O (20 mL) at 0 °C. The yellow suspension
was raised to ambient temperature and stirred for 18 h. The
precipitate was filtered. Hexane was added to the filtrate and
concentrated under reduced pressure. Compound 3 was ob-
tained as pale yellow crystals. Yield: 0.70 g (73%). Mp: 254
[(Me3SiNdP P h 2)2CdGe(µ-Se)]2 (7). A solution of 4 (0.68
g, 0.54 mmol) in THF (30 mL) was added dropwise to the
colorless solution of powdered selenium (0.089 g, 1.13 mmol)
in THF (30 mL) at 0 °C with stirring in the absence of light.
The resultant orange solution was raised to room temperature
and stirred for 2 days. It was filtered and concentrated,
obtaining yellow crystals of 7. Yield: 0.17 g (23%). Mp: 328
°C (dec). Anal. Found: C, 51.87; H, 5.58; N, 3.95. Calcd for
°C (dec). Anal. Found: C, 57.08; H, 6.15; N, 4.24. Calcd for
1
C
31H39ClGeN2P2Si2‚1/2 hexane: C, 57.68; H, 6.40; N, 3.96. H
62H76N4Ge2P4Se2Si2: C, 52.49; H, 5.54; N, 3.95. 1H NMR
NMR (THF-d8): δ -0.15 (s, 18H, SiMe3), 3.50 (t, J P-H ) 12
C
Hz, 1H, PC(H)P), 7.29-7.37 (m, 13H, Ph), 7.66-7.72 (m, 7H,
(THF-d8): δ -0.48 (s, 18H, SiMe3), -0.25 (s, 18H, SiMe3),
7.18-7.42 (m, 24H, Ph), 7.49-7.58 (m, 4H, Ph), 7.61-7.68 (m,
8H, Ph), 7.78-7.85 (m, 4H, Ph). 13C{1H} NMR (THF-d8): δ
Ph). 13C{1H} NMR (THF-d8): δ 3.01 (SiMe3), 37.14 (t, J P-C
)
1
2
270.9 Hz, PCP), 128.58 (t, J P-C ) 24.0 Hz, m-Ph and p-Ph),
2
131.14 (s, o-Ph), 132.31 (t, J P-C ) 21.0 Hz, ipso-Ph). 31P{1H}
1
2.50, 4.39 (SiMe3), 128.49 (d, J P-C ) 47.7 Hz, m-Ph), 128.81
(s, o-Ph), 129.18 (d, 1J P-C ) 50.7 Hz, ipso-Ph), 130.37 (s, p-Ph),
131.46 (s, p-Ph′), 132.68 (s, m-Ph′), 132.90 (d, 1J P-C ) 43.8 Hz,
NMR (THF-d8): δ 13.97.
[(Me3SiNdP P h 2)2CdGefGedC(P P h 2dNSiMe3)2] (4).4
Method A: A solution of 3 (1.30 g 1.95 mmol) in toluene (30
mL) was added to a stirred solution of [Ge{N(SiMe3)2}2] (0.49
g, 1.25 mmol) in toluene (30 mL) at room temperature. The
1
o-Ph′), 133.91 (d, J P-C ) 46.8 Hz, ipso-Ph′). 31P{1H} NMR
(THF-d8): δ 13.97, 60.80. 77Se NMR (THF-d8): δ 860.88. FAB-
MS: m/z found 711.0510; calcd for C31H38N2GeP2SeSi2 711.0499
([M/2 + H]+).
(20) Tokitoh, N.; Matsumoto, T.; Manmaru, K.; Okazaki, R. J . Am.
Chem. Soc. 1993, 115, 8855.
(21) Kishikawa, K.; Tokitoh, N.; Okazaki, R. Organometallics 1997,
16, 5127.
(22) Fjeldberg, T.; Haaland, A.; Schilling, B. E. R.; Lappert, M. F.;
Thorne, A. J . J . Chem. Soc., Dalton Trans. 1986, 1551.
[(Me3SiNdP P h 2)2CdGe(µ-Te)]2 (8). A solution of 4 (0.72
g, 0.57 mmol) in THF (30 mL) was added slowly to the colorless
solution of powdered tellurium (0.15 g, 1.18 mmol) in THF (30
mL) at 0 °C with stirring in the absence of light. The resultant
red solution was raised to room temperature and stirred for 2

Synthesis of Bisgermavinylidene
Organometallics, Vol. 22, No. 21, 2003 4311
days. The unreacted tellurium power was filtered off; the
filtrate was concentrated, yielding red crystals of 8. Yield: 0.31
g (36%). Mp: 258 °C (dec). Anal. Found: C, 48.48; H, 4.85; N,
3.90. Calcd for C62H76N4Ge2P4Si2Te2: C, 49.19; H, 5.06; N, 3.70.
1H NMR (THF-d8): δ -0.48 (s, 18H, SiMe3), -0.15 (s, 18H,
SiMe3), 7.21-7.42 (m, 22H, Ph), 7.45-7.53 (m, 4H, Ph), 7.67-
7.78 (m, 14H, Ph). 13C{1H} NMR (THF-d8): δ 2.38, 4.12
Hydrogen atoms were introduced in their idealized positions
and included in structure factor calculations with assigned
isotropic temperature factor calculations. Full details of the
crystallographic analysis of 2, 3, and 5-8 are given in the
Supporting Information.
Ack n ow led gm en t. This work was supported by the
Hong Kong Research Grants Council (Project No. CUHK
4023/02P).
1
2
(SiMe3), 128.21 (d, J P-C ) 46.5 Hz, m-Ph), 128.58 (t, J P-C
)
24.0 Hz, o-Ph), 128.85 (d, 1J P-C ) 49.8 Hz, ipso-Ph), 130.00 (s,
p-Ph), 131.14 (s, p-Ph′), 132.46 (m, m-Ph′ and o-Ph′), 133.36
(d, 1J P-C ) 46.2 Hz, ipso-Ph′). 31P{1H} NMR (THF-d8): δ 11.78,
58.97. 125Te NMR (THF-d8): δ 1025.53. FAB-MS: m/z found
761.0409; calcd for C31H38N2GeP2Si2Te 761.0396 ([M/2 + H]+).
Su p p or tin g In for m a tion Ava ila ble: Details of the X-ray
crystal structures, including ORTEP diagrams and tables of
crystal data and structure refinement, atomic coordinates,
bond lengths and angles, and anisotropic displacement pa-
rameters for 2, 3, and 5-8. This material is available free of
charge via the Internet at http://pubs.acs.org.
X-r a y Cr ysta llogr a p h y. Single crystals were sealed in 0.3
or 0.5 mm Lindemann glass capillaries under nitrogen. X-ray
data of 2, 3, and 5-8 were collected on a Rigaku R-AXIS II
imaging plate using graphite-monochromatized Mo KR radia-
tion (I ) 0.71073 Å) from a rotating-anode generator operating
at 50 kV and 90 mA. Crystal data for 2, 3, and 5-8 are
summarized in Table 1. The structures were solved by direct
phase determination using the computer program SHELXTL-
PC24 on a PC 486 and refined by full-matrix least squares with
anisotropic thermal parameters for the non-hydrogen atoms.
OM034071T
(23) Chorley, R. W.; Hitchcock. P. B.; Lappert, M. F.; Leung, W.-P.;
Power, P. P.; Olmstead, M. M. Inorg. Chim. Acta 1992, 198.
(24) Sheldrick, G. M. In Crystallographic Computing 3: Data
Collection, Structure Determination, Proteins, and Databases; Sheld-
rick, G. M., Kru¨ger, C., Goddard, R., Eds.; Oxford University Press:
New York, 1985; p 175.