Molybdenum and tungsten germylyne complexes of the general formula trans-[X(dppe)2M≡Ge-(η1-Cp*)] (X = Cl, Br, I; dppe = Ph2PCH2CH2PPh2; Cp* = C5Me5): Syntheses, molecular structures, and bonding features of the germylyne ligand

Article abstract of DOI:10.1021/om010785x

The halogermylenes (Cp*GeX)_n (1a, X = Cl, n = 1; 1b, X = Br, n = 2; Cp* = pentamethylcyclopentadienyl) were prepared in high yield by a redistribution reaction of GeCp*₂ with GeX₂(1,4-dioxane). The ionic compounds [Cp*Ge] [GeX₃] (2a, X = Cl; 2b, X = Br) were also formed to a small extent in this reaction. Treatment of trans-[Mo(dppe)₂(N₂)₂] (3) (dppe = Ph₂PCH₂CH₂PPh₂) with 1 equiv of 1a,b affords in refluxing toluene the germylyne complexes trans-[X(dppe)₂Mo≡Ge-(η¹-Cp*)] (4a, X = Cl; 4b, X = Br). Concomitant formation of GeCp*₂ and the dihalo complexes trans-[Mo(dppe)₂(X)₂] (5a, X = Cl; 5b, X = Br) is observed in this reaction. In comparison, the reactions of trans-[W(dppe)₂(N₂)₂] (6) with 1a,b and (Cp*GeI)_∞ (1c) afford selectively the germylyne complexes trans-[X(dppe)₂W≡Ge-(η¹-Cp*)] (7a-c). The molecular structures of 4a·0.5pentane and 4b·0.5pentane reveal very short Mo-Ge bonds, almost linear Mo-Ge-C(Cp*) sequences, and an η¹-bonded Cp* substituent indicating the presence of a molybdenum-germanium triple bond. The structural features of the germylyne ligand in 4a and 4b are compared with those in the corresponding tungsten complexes trans-[X(dppe)₂W≡Ge-(η¹-Cp*)] (7a-c), and the bonding parameters of the Cp* substituent are shown to be similar to those in the germanes (η¹-Cp*)GeI₃ (8) and (η¹-Cp*)₂GeCl₂ (9).

Full text of DOI:10.1021/om010785x

Organometallics 2002, 21, 653-661
653
Molybd en u m a n d Tu n gsten Ger m ylyn e Com p lexes of th e
Gen er a l F or m u la tr a n s-[X(d p p e)2MtGe-(η1-Cp *)] (X ) Cl,
Br , I; d p p e ) P h 2P CH2CH2P P h 2; Cp * ) C5Me5):
Syn th eses, Molecu la r Str u ctu r es, a n d Bon d in g F ea tu r es
of th e Ger m ylyn e Liga n d
Alexander C. Filippou,* Peter Portius, and Athanassios I. Philippopoulos
Fachinstitut fu¨r Anorganische und Allgemeine Chemie, Humboldt-Universita¨t zu Berlin,
Hessische Strasse 1-2, D-10115 Berlin, Germany
Received August 28, 2001
The halogermylenes (Cp*GeX)n (1a , X ) Cl, n ) 1; 1b, X ) Br, n ) 2; Cp* )
pentamethylcyclopentadienyl) were prepared in high yield by a redistribution reaction of
GeCp*2 with GeX2(1,4-dioxane). The ionic compounds [Cp*Ge][GeX3] (2a , X ) Cl; 2b, X )
Br) were also formed to a small extent in this reaction. Treatment of trans-[Mo(dppe)2(N2)2]
(3) (dppe ) Ph2PCH2CH2PPh2) with 1 equiv of 1a ,b affords in refluxing toluene the germylyne
complexes trans-[X(dppe)2MotGe-(η1-Cp*)] (4a , X ) Cl; 4b, X ) Br). Concomitant formation
of GeCp*2 and the dihalo complexes trans-[Mo(dppe)2(X)2] (5a , X ) Cl; 5b, X ) Br) is observed
in this reaction. In comparison, the reactions of trans-[W(dppe)2(N2)2] (6) with 1a ,b and
(Cp*GeI)∞ (1c) afford selectively the germylyne complexes trans-[X(dppe)2WtGe-(η1-Cp*)]
(7a -c). The molecular structures of 4a ‚0.5pentane and 4b‚0.5pentane reveal very short Mo-
Ge bonds, almost linear Mo-Ge-C(Cp*) sequences, and an η1-bonded Cp* substituent
indicating the presence of a molybdenum-germanium triple bond. The structural features
of the germylyne ligand in 4a and 4b are compared with those in the corresponding tungsten
complexes trans-[X(dppe)2WtGe-(η1-Cp*)] (7a -c), and the bonding parameters of the Cp*
substituent are shown to be similar to those in the germanes (η1-Cp*)GeI3 (8) and (η1-Cp*)2-
GeCl2 (9).
In tr od u ction
germanium.4 In continuation of our work in this field
we report here on the syntheses and molecular struc-
tures of the molybdenum germylyne complexes trans-
[X(dppe)2MotGe-(η1-Cp*)] (4a , X ) Cl; 4b, X ) Br).
The structural features of the germylyne ligand in 4a
and 4b are compared with those in the tungsten
congeners trans-[X(dppe)2WtGe-(η1-Cp*)] (X ) Cl, Br,
I) (7a -c) and the dicarbonyl complexes [(η5-C5H5)-
(CO)2MtGe-R]. The molecular structures of (η1-Cp*)-
GeI3 (8) and (η1-Cp*)2GeCl2 (9) are reported and the
bonding mode of the Cp* group in 4a ,b and 7a -c
compared with that in 8 and 9.
Numerous transition metal carbyne complexes have
been prepared and their reactions studied in detail.1 In
comparison, complexes containing a triple bond between
a transition metal and a group 14 element that is
heavier than carbon are very rare. In fact, silylyne,
stannylyne, and plumbylyne complexes are presently
unknown, and in the case of germanium only two classes
of compounds have been described so far.2 The first one
includes the dicarbonyl complexes [(η5-C5H5)(CO)2-
MtGe-R] (M ) Cr, Mo, W), bearing a sterically very
demanding substituent R at the germanium atom (R )
C6H3-2,6-Trip2 (Trip ) C6H2-2,4,6-iPr3), C6H3-2,6-Mes2
(Mes ) C6H2-2,4,6-Me3)).3 The second class form the
tungsten diphosphane complexes trans-[X(dppe)2-
WtGe-(η1-Cp*)] (X ) Cl, Br, I), in which the Cp*
substituent as potential leaving group is bonded to
Resu lts a n d Discu ssion
Starting materials for the reactions described below
were the halogermylenes (Cp*GeX)n (1a , X ) Cl, n ) 1;
1b, X ) Br, n ) 2; 1c, X ) I, n ) ∞)5-7 and the
dinitrogen complexes trans-[M(dppe)2(N2)2] (3, M ) Mo;
6, M ) W).8 For the synthesis of the halogermylenes
* Correspondence author. E-mail: filippou@chemie.hu-berlin.de.
(1) (a) Fischer, H.; Hofmann, P.; Kreissl, F. R.; Schrock, R. R.;
Schubert, U.; Weiss, K. Carbyne Complexes; VCH: Weinheim, Ger-
many, 1988. (b) Filippou, A. C.; Portius, P.; J ankowski, C. J . Orga-
nomet. Chem. 2001, 617-618, 656-670, and references therein.
(2) J utzi, P. Angew. Chem. 2000, 112, 3953-3957; Angew. Chem.,
Int. Ed. 2000, 39, 3797-3800.
(3) (a) Simons, R. S.; Power, P. P. J . Am. Chem. Soc. 1996, 118,
11966-11967. (b) Pu, L.; Twamley, B.; Haubrich, S. T.; Olmstead, M.
M.; Mork, B. V.; Simons, R. S.; Power, P. P. J . Am. Chem. Soc. 2000,
122, 650-656.
(4) Filippou, A. C.; Philippopoulos, A. I.; Portius, P.; Neumann, D.
U. Angew. Chem. 2000, 112, 2881-2884; Angew. Chem., Int. Ed. 2000,
39, 2778-2781.
9
1a and 1b a redistribution reaction of GeCp*2 with
(5) Kohl, F. X.; J utzi, P. J . Organomet. Chem. 1983, 243, 31-34.
(6) Winter, J . G.; Portius, P.; Kociok-Ko¨hn, G.; Steck, R.; Filippou,
A. C. Organometallics 1998, 17, 4176-4182.
(7) Compound 1b is composed in the solid state of Br-bridged dimers,
whereas 1c forms an I-bridged coordination polymer with a ladder
structure (ref 6). Ebullioscopic measurements show, however, that 1b
and 1c are dissociated into monomers in CH2Cl2. Therefore all
subsequent remarks and calculations in this publication are based on
the monomers.
10.1021/om010785x CCC: $22.00 © 2002 American Chemical Society
Publication on Web 01/24/2002

654 Organometallics, Vol. 21, No. 4, 2002
Filippou et al.
GeX2(1,4-dioxane) (X ) Cl, Br)10 was used (eq 1).
Compounds 1a and 1b were thereby obtained as pale
of the reaction solutions, which revealed that the ν(N2)
absorptions of 3 at 2040 and 1977 cm-1 have disap-
peared within a few minutes. No intermediates could
be observed by IR or 31P{1H} NMR spectroscopy. The
31P{1H} spectra of the crude products, which were
obtained after evaporation of the solvent, showed in
C6D6 that the singlet resonance of the starting material
at δ 66.4 had been replaced by one singlet resonance
(4a , δ 66.7; 4b, δ 65.0), suggesting at first glance the
exclusive formation of the molybdenum germylyne
complexes.12 However, the 1H NMR spectra of the crude
products revealed the presence of two other compounds,
which by comparison with authentic samples were
idendified to be trans-[Mo(dppe)2(X)2] (5a , X ) Cl; 5b,
X ) Br)13 and GeCp*2,9 respectively (eq 2).14 The molar
ratio of 4a /5a /GeCp*2 and of 4b/5b/GeCp*2 was found
green-yellow (1a ) and white (1b) microcrystalline solids
in 90 and 88% yields, respectively, and were identified
by comparison of their NMR spectra with those of
analytically pure samples obtained as described previ-
ously.5,6 Both compounds are very air-sensitive, discol-
oring in air rapidly to yellow and then to brown, and
are thermally very stable. Thus, no evidence for decom-
position was found by NMR spectroscopy when 1a ,b
were heated under rigorous exclusion of air for 15 min
at 110 °C in toluene-d8. The ionic compounds [Cp*Ge]-
[GeCl3] (2a )5 and [Cp*Ge][GeBr3] (2b) were also formed
to a small extent in the reaction of GeCp*2 with GeX2-
(1,4-dioxane) (X ) Cl, Br). These were easily separated
from 1a ,b taking advantage of their insolubility in
pentane and isolated as white solids in 5 and 6% yields,
respectively. Compound 2b is a moderately air-sensitive
solid that is soluble in CH2Cl2 but insoluble in diethyl
1
by H NMR spectroscopy to be approximately 12/1/1.3
and 5.1/1/1.1, respectively. GeCp*2 could be easily
removed upon washing the crude products with pen-
tane. Separation of 4a ,b from 5a ,b proved however
difficult, the germylyne complexes 4a and 4b enhancing
the solubility of the less soluble dihalides 5a and 5b in
THF, toluene, and diethyl ether. This was finally
achieved by repeated fractional crystallization from hot
toluene to afford the germylyne complexes as orange-
brown, very air-sensitive solids, which contain 1 mol of
toluene. Both compounds show a remarkable thermal
stability and decompose upon melting at 236 and 224
°C, respectively. They are soluble in THF and warm
toluene to give dark red solutions, which brighten
rapidly upon exposure to air. The oxidation results in a
mixture of presently unknown products. The IR spectra
of 4a ‚toluene and 4b‚toluene are essentially identical
in the region 4000-400 cm-1 as expected for isostruc-
tural complexes, and the 31P{1H} NMR spectra display
in THF-d8 one singlet resonance for the chemically
equivalent dppe ligands at δ 66.6 and 64.9, respectively.
1
ether and melts at 134-140 °C. The H NMR spectrum
of 2b displays in CD2Cl2 at ambient temperature one
singlet resonance for the methyl protons at δ 2.17, and
the 13C{1H} NMR spectrum one singlet resonance for
the methyl and the ring carbon nuclei at δ 9.8 and 121.8,
respectively. The methyl proton resonance appears at
lower field than that of 1b (δ ) 2.00 (CD2Cl2, RT)) and
at a position close to that found for other salts bearing
the [Cp*Ge]+ cation (δMe (CD2Cl2, RT): 2a, 2.16; [Cp*Ge]-
[BF4], 2.16; [Cp*Ge][InCl4], 2.21).11 The ionic character
of 2a and 2b was confirmed by single-crystal X-ray
structural analyses.11
Heating of an equimolar mixture of trans-[Mo(dppe)2-
(N2)2] (3) and 1a ,b in boiling toluene resulted in the
formation of the germylyne complexes trans-[X(dppe)2-
MotGe-(η1-Cp*)] (4a , X ) Cl; 4b, X ) Br) (eq 2).
Furthermore the 1H NMR spectra show in THF-d8
a
double set of resonances for the diastereotopic methyl-
ene protons at δ 2.45 and 2.83 (4a ‚toluene) and δ 2.49
and 2.93 (4b‚toluene), and the 13C{1H} NMR spectra
display a double set of resonances for the diastereotopic
phenyl substituents of each PPh2 group (Experimental
Section). All these spectroscopic data indicate the pres-
ence of diamagnetic complexes of the general formula
trans-[Mo(dppe)2(L)(L′)]. Finally, one singlet resonance
is observed for the methyl protons of the Cp* group in
(11) Filippou, A. C.; Portius, P.; Philippopoulos, A. I.; Neumann, D.
U.; Bader, K. G.; Steck, R. Unpublished work.
(12) When the reactions of 3 with 1a ,b were carried out in toluene,
which after drying with Na/benzophenone and deoxygenation was
stored under inert gas for several days over 4 Å sieves in Schlenk flasks
with a plastic stopper, the 31P{1H} NMR spectrum of the crude product
in C6D6 displayed an additional singlet at δ 68.5 (in the case of 3a )
and 67.2 (in the case of 3b), indicating the formation of a second
diamagnetic product. This product did not contain
a Cp* group
according to 1H NMR spectroscopy and is probably the result of
oxidation/hydrolysis of the germylyne complexes 4a and 4b.
(13) (a) Anker, M. W.; Chatt, J .; Leigh, G. J .; Wedd, A. G. J . Chem.
Soc., Dalton Trans. 1975, 2639-2645. (b) Ito, T.; Yamamoto, A. J .
Chem. Soc., Dalton Trans. 1975, 1398-1401. (c) Filippou, A. C.;
Portius, P.; Philippopoulos, A. I.; Kociok-Ko¨hn, G.; Ziemer, B. Acta
Crystallogr. 2000, C56, e378-e379.
Evidence for a fast reaction was given by the IR spectra
(8) Dilworth, J . R.; Richards, R. L. Inorg. Synth. 1980, 20, 119-
127.
(9) J utzi, P.; Kohl, F.; Hofmann, P.; Kru¨ger, C.; Tsay, Y.-H. Chem.
Ber. 1980, 113, 757-769.
(10) (a) Kolesnikov, S. P.; Rogozhin, I. S.; Nefedov, O. M. Chem.
Abstr. 1975, 82, 25328u. (b) Kouvetakis, J .; Haaland, A.; Shorokhov,
D. J .; Volden, H. V.; Girichev, G. V.; Sokolov, V. I.; Matsunaga, P. J .
Am. Chem. Soc. 1998, 120, 6738-6744.
(14) 1H NMR data of GeCp*2 and 4a ,b in C6D6 at room tempera-
ture: GeCp*2, δ 1.94 (s, 15H, C5Me5); 4a , δ 8.01 (s, 8H), 8.75 (s, ∆ν1/2
) 25 Hz, 8H), 8.94 (s, ∆ν1/2 ) 32 Hz, 16H), 15.23 (s, ∆ν1/2 ) 227 Hz,
16H) (∆ν1/2 of the solvent signal ) 12 Hz); 4b, δ 8.85 (s, ∆ν1/2 ) 13 Hz,
8H), 9.12 (s, ∆ν1/2 ) 14 Hz, 16H), 9.40 (s, ∆ν1/2 ) 34 Hz, 8H), 17.72 (s,
∆ν1/2 ) 45 Hz, 16H) (∆ν1/2 of the solvent signal ) 3.6 Hz). No 31P NMR
signals were observed for the paramagnetic complexes 4a and 4b.

Molybdenum and Tungsten Germylyne Complexes
Organometallics, Vol. 21, No. 4, 2002 655
1
the H NMR spectra of 4a ‚toluene (δ ) 1.41 (THF-d8);
δ ) 1.50 (C6D6)) and 4b‚toluene (δ ) 1.36 (THF-d8); δ
) 1.46 (C6D6)) at room temperature. This reveals a fast
haptotropic shift of the Cp* substituent on the NMR
time scale, if one takes into account the solid-state
molecular structures of 4a and 4b (vide infra). The
activation energy for this process should be low given
the fact that the static structures of 4a ‚toluene and of
4b‚toluene cannot be frozen out in toluene-d8 at -73
°C (300 MHz spectrometer). This agrees fully with the
results of density functional theory (DFT) calculations
on the related model compounds trans-[Cl(L)4WtGe-
(η1-Cp)] (L ) CO, PH3; Cp ) C5H5).4 The energy barrier
for the haptotropic shift involving a transition state
structure with an η2-bonded Cp group is at 3.7 kJ /mol
(L ) CO) and 10.8 kJ /mol (L ) PH3), which is consider-
ably smaller than that of cyclopentadienyl germanes.15
The reactions of the corresponding tungsten com-
pound trans-[W(dppe)2(N2)2] (6) with the haloger-
mylenes 1a -c7 are much more selective than those of
the molybdenum complex 3 mentioned above and afford
the tungsten germylyne complexes trans-[X(dppe)2-
WtGe-(η1-Cp*)] (7a , X ) Cl; 7b, X ) Br; 7c, X ) I) in
good yields (eq 3).4 Only a tiny amount of trans-
F igu r e 1. DIAMOND plot of the molecular structure of
trans-[Br(dppe)2MotGe-(η1-Cp*)] (4b) with thermal el-
lipsoids drawn at the 50% probability level. Hydrogen
atoms are omitted for clarity.
[W(dppe)2(X)2] (X ) Cl, Br, I) and GeCp*2 were formed
in these reactions according to 1H NMR spectros-
copy, and no intermediates could be detected by IR or
31P{1H} NMR spectroscopy as in the molybdenum case
(vide supra). The germylyne complexes 7a -c were
isolated as orange-brown (7a ,b) and red-brown (7c)
solids, which are less air-sensitive and thermally more
stable than their molybdenum congeners 4a and 4b .
7a -c have spectroscopic properties similar to 4a and
4b (Experimental Section).4
The solid-state structures of the germylyne complexes
4a ‚0.5pentane, 4b‚0.5pentane, 7b‚0.5pentane, and 7c‚
toluene were determined by single-crystal X-ray dif-
fraction. Suitable dark red crystals of 4a ‚0.5pentane,
4b‚0.5pentane, and 7b‚0.5pentane were obtained upon
diffusion of pentane into a toluene solution (4a ) or a
THF solution (4b, 7b) at 4 and 20 °C, respectively. Red-
brown crystals of 7c‚toluene were grown upon slow
cooling of a hot saturated toluene solution of 7c to room
temperature. The pentane hemisolvates of 4a , 4b, and
7b are isostructural and crystallize in the space groups
I2/a (4a , 4b) and C2/c (7b). Similarly, the toluene
solvates of 7a and 7c are isostructural and crystallize
in the space group P1h. The molecular structures of 4b
and 7c are depicted in Figures 1 and 2, and selected
bond lengths and angles of all germylyne complexes are
listed in Table 1 including those of 7a ‚toluene4 for
comparison reasons.
F igu r e 2. DIAMOND plot of the molecular structure of
trans-[I(dppe)2WtGe-(η1-Cp*)] (7c) with thermal ellip-
soids drawn at the 50% probability level. Hydrogen atoms
are omitted for clarity.
germylyne ligand occupy trans positions. This agrees
fully with the results of the NMR studies in solution
(vide supra). Complexes 4a , 4b, and 7b differ from 7a
and 7c in the conformation adopted by the Cp* sub-
stituent and the phenyl groups (Figure 3).
The Mo-Br distance of 4b‚0.5pentane (264.06(7) pm)
is 9 pm shorter than that of the related carbyne complex
trans-[Br(dppe)2MotC-SiMe3] (Mo-Br ) 273.1(2) pm)16
and the W-Br distance of 7b‚0.5pentane (263.8(2) pm)
10.6 pm shorter than that of trans-[Br(dmpe)2WtC-
Ph] (W-Br ) 274.4(2) pm, dmpe ) Me2PCH2CH2-
All germylyne complexes reveal a distorted octahedral
coordination geometry, in which the halogen and the
(16) Ahmed, K. J .; Chisholm, M. H.; Huffman, J . C. Organometallics
1985, 4, 1168-1174.
(15) J utzi, P. Chem. Rev. 1986, 86, 983-996.

656 Organometallics, Vol. 21, No. 4, 2002
Filippou et al.
Ta ble 1. Selected Bon d Len gth s (p m ) a n d An gles (d eg) w ith Estim a ted Sta n d a r d Devia tion s of th e
Ger m ylyn e Com p lexes tr a n s-[X(d p p e)2MtGe-(η1-Cp *)] (4, M ) Mo; 7, M )W; a , X ) Cl; b, X ) Br ; c, X ) I)
4a ‚0.5pentane
4b‚0.5pentane
7a ‚toluene
7b‚0.5pentane
7c‚toluene
M-Ge
231.85(6)
251.2(1)
250.4(1)
252.8(1)
249.1(1)
247.0(1)
249.8(1)
204.9(4)
148.1(5)
135.4(6)
146.8(6)
136.0(6)
149.6(6)
172.0(1)
171.36(3)
101.67(3)
87.82(3)
91.31(3)
89.64(3)
81.52(3)
84.83(3)
86.50(3)
98.16(3)
115.9
231.03(6)
264.06(7)
249.7(1)
253.1(1)
248.8(1)
247.8(1)
249.8(1)
202.9(5)
149.6(7)
135.3(7)
146.2(7)
134.1(7)
150.8(7)
171.6(2)
171.35(2)
101.49(3)
87.97(3)
91.35(3)
89.18(3)
82.08(3)
84.87(3)
86.07(3)
98.48(3)
116.8
230.2(1)
248.6(1)
246.9(1)
248.9(1)
245.5(1)
244.6(1)
246.5(1)
203.8(5)
150.0(8)
136.7(8)
145.1(8)
137.2(7)
147.7(8)
172.2(2)
174.04(3)
101.81(4)
94.16(5)
87.80(4)
92.11(5)
81.85(5)
81.87(5)
88.91(5)
92.17(5)
109.6
229.3(1)
263.8(2)
248.0(3)
250.6(3)
247.0(3)
245.9(4)
247.9(3)
203.0(8)
149.6(10)
133.9(11)
146.0(12)
135.4(11)
148.6(11)
172.4(2)
171.23(3)
101.81(7)
88.25(8)
91.63(7)
89.33(8)
81.98(7)
84.62(9)
85.63(7)
98.36(9)
116.9
230.60(9)
282.76(9)
249.6(2)
249.0(2)
250.0(2)
245.8(2)
248.6(2)
204.9(6)
149.3(9)
137.1(9)
147.3(9)
133.5(9)
149.5(8)
172.6(2)
173.90(2)
100.96(4)
93.81(4)
87.46(4)
92.47(4)
82.96(4)
82.36(4)
88.95(4)
91.73(4)
109.4
M-X
M-P(1)
M-P(2)
M-P(3)
M-P(4)
(M-P)av
Ge-C(1)
C(1)-C(2)
C(2)-C(3)
C(3)-C(4)
C(4)-C(5)
C(5)-C(1)
M-Ge-C(1)
Ge-M-X
Ge-M-P(1)
Ge-M-P(2)
Ge-M-P(3)
Ge-M-P(4)
X-M-P(1)
X-M-P(2)
X-M-P(3)
X-M-P(4)
Ge-C(1)-Cg
a
Ge-C(1)-C(2)
Ge-C(1)-C(5)
Ge-C(1)-C(6)
C(2)-C(1)-C(5)
C(2)-C(1)-C(6)
C(5)-C(1)-C(6)
105.7(3)
105.4(3)
110.8(3)
104.5(3)
114.4(4)
115.2(4)
107.0(3)
106.1(3)
111.4(3)
103.7(4)
114.0(4)
114.1(4)
100.3(3)
105.2(3)
111.7(4)
104.7(4)
117.1(5)
116.1(4)
105.9(5)
106.7(5)
110.7(5)
103.8(6)
114.2(7)
114.7(7)
100.1(4)
105.6(4)
111.4(4)
103.6(5)
118.3(6)
115.9(5)
a
Cg denotes the center of the C5 ring.
average M-P bond lengths in the series cis- or trans-
[M(P)4(N2)2] < trans-[X(P)4MtGe-(η1-Cp*)] < trans-
[M(P)4(X)2] (Table 2), which indicates a weakening of
the M-P bonds. This suggests in the absence of any
steric effects a reduction of the electron density at the
metal center and a decrease of the metal-phosphane
back-bonding in the same series. Additional evidence
that the M-P bonds of the germylyne complexes trans-
[X(P)4MtGe-(η1-Cp*)] are weaker than those of the bis-
dinitrogen complexes cis- or trans-[M(P)4(N2)2] is given
1
by the J (W,P) coupling constants of the complex pairs
7a /6 (1J (W,P) ) 258.8/320.8 Hz)4,11 and trans-[Cl-
(PMe3)4WtGe-(η1-Cp*)]/cis-[W(PMe3)4(N2)2] (1J (W,P) )
264.1/312, 314 Hz).11,20b
Striking features of the molecular structures of the
germylyne complexes are however the very short M-Ge
bonds, the almost linear M-Ge-C(Cp*) linkages, and
the η1-coordination of the Cp* substituent, which sug-
gest in agreement with the results of theoretical calcu-
lations the presence of metal-germanium triple bonds
in these compounds.4 Thus, the Mo-Ge bond length of
4a ‚0.5pentane is at 231.85(6) pm and that of 4b‚
0.5pentane at 231.03(6) pm, which is considerably
smaller than Mo-Ge single bond lengths. The latter
range from 250 to 266 pm depending on the coordination
sphere of molybdenum and the other substituents at the
germanium atom, e.g., trans-[(η5-Cp)Mo(CO)2(PMe3)-
F igu r e 3. View of 4b down the Ge-Mo-Br axis and of
7c down the Ge-W-I axis showing the different conforma-
tions of the Cp* ring and the diphosphane ligands.
PMe2).17 Similarly, the Mo-Cl distance of 4a ‚0.5pen-
tane (251.2(1) pm) is 7.3 pm shorter than that of the
electronically related carbyne complex trans-[Cl-
{P(OMe)3}4MotC-Ph] (Mo-Cl ) 258.5(3) pm).18 All
these data indicate a weaker trans influence19 of the
germylyne ligand Ge(η1-Cp*) than that of the carbyne
ligands CPh and CSiMe3. A comparison of the germy-
lyne complexes trans-[X(P)4MtGe-(η1-Cp*)] (M ) Mo,
W; P ) 0.5dppe, PMe3; X ) Cl, Br) with the bis-
dinitrogen complexes cis- or trans-[M(P)4(N2)2]20 and the
dihalides trans-[M(P)4(X)2]21 reveals an increase of the
(20) (a) Uchida, T.; Uchida, Y.; Hidai, M.; Kodama, T. Acta Crys-
tallogr. B 1975, 31, 1197-1199. (b) Carmona, E.; Marin, J . M.; Poveda,
M. L.; Atwood, J . L.; Rogers, R. D. J . Am. Chem. Soc. 1983, 105, 3014-
3022. (c) Hu, C.; Hodgeman, W. C.; Bennett, D. W. Inorg. Chem. 1996,
35, 1621-1626.
(21) (a) Agaskar, P. A.; Cotton, F. A.; Derringer, D. R.; Powell, G.
L.; Root, D. R.; Smith, T. J . Inorg. Chem. 1985, 24, 2786-2791. (b)
Carmona, E.; Marin, J . M.; Poveda, M. L.; Atwood, J . L.; Rogers, R. D.
Polyhedron 1983, 2, 185-193.
(17) Manna, J .; Gilbert, T. M.; Dallinger, R. F.; Geib, S. J .; Hopkins,
M. D. J . Am. Chem. Soc. 1992, 114, 5870-5872.
(18) Mayr, A.; Dorries, A. M.; McDermott, G. A.; van Engen, D.
Organometallics 1986, 5, 1504-1506.
(19) Lyne, P. D.; Mingos, D. M. P. J . Chem. Soc., Dalton Trans. 1995,
1635-1643, and references therein.

Molybdenum and Tungsten Germylyne Complexes
Organometallics, Vol. 21, No. 4, 2002 657
Ta ble 2. Com p a r ison of th e M-P a n d M-X Bon d Len gth s of th e Com p lexes cis- or tr a n s-[M(P )4(N2)2],
tr a n s-[X(P )4MtGe-(η1-Cp *)], a n d tr a n s-[M(P )4(X)2] (M ) Mo, W; P ) 0.5d p p e, P Me3; X ) Cl, Br )a
complex
M-Pb
M-X
ref
trans-[Mo(dppe)2(N2)2] (3)
245.4(1)
249.8(1)
251.4(2)
249.8(1)
252.0(1)
245.2(3)e
247.9(2)
249.6(3)
245.4(3)
246.5(1)
250.1(1)
20a
this work
13c
this work
21a
20b
11
21b
20c
4
trans-[Cl(dppe)2MotGe-(η1-Cp*)] (4a )c
trans-[Mo(dppe)2(Cl)2] (5a )d
trans-[Br(dppe)2MotGe-(η1-Cp*)] (4b)c
trans-[Mo(dppe)2(Br)2] (5b)
cis-[Mo(PMe3)4(N2)2]
251.2(1)
243.4(2)
264.06(7)
256.9(1)
trans-[Cl(PMe3)4MotGe-(η1-Cp*)]f
trans-[Mo(PMe3)4(Cl)2]
253.4(2)
242.0(6)
trans-[W(dppe)2(N2)2] (6)
trans-[Cl(dppe)2WtGe-(η1-Cp*)] (7a )c
trans-[W(dppe)2(Cl)2]c
248.6(1)
242.3(1)b
11
a
b
Bond lengths are given in pm and estimated standard deviations in parentheses. Average M-P and M-Cl bond lengths. c Bonding
d
parameters of the hemipentane (0.5C5H12) solvates of 4a , 4b and trans-[W(dppe)2(Cl)2] and the toluene solvate of 7a . Average M-P and
M-Cl bond lengths of the hemipentane solvate and the ditetrahydrofurane solvate (2C4H8O) of 5a . e The average Mo-P bond lengths of
the trans- and cis-coordinated PMe3 ligands do not differ significantly ((Mo-P)trans ) 245.3(3) pm; (Mo-P)cis ) 245.0(3) pm). f Average
values of the two crystallographically independent molecules.
(GeCl3)] ((Mo-Ge)av ) 250.57(6) pm),22a trans-[(η5-Cp)-
Mo(CO)2(PMe3)(GeCl2H)] (Mo-Ge ) 253.1(2) pm),22b
[(η5-Cp)Mo(CO)3(GeCl3)] (Mo-Ge ) 254.6(1) pm),22a
[(η5-Cp)Mo(η3-C6H11)(NO)(GePh3)] (Mo-Ge ) 260.4(2)
pm),23 [(η5-Cp)Mo(CO)2{C(OEt)Ph}(GePh3)] (Mo-Ge )
265.8(2) pm),24 and [{(η5-Cp)Mo(CO)3}2GeCl2] ((Mo-
Ge)av ) 266.02(7) pm).22c The Mo-Ge triple bonds of
4a ,b are 3-5 pm longer than those of the dicarbonyl
complexes [(η5-C5H5)(CO)2MotGe-C6H3-2,6-R2] (R )
Mes, Mo-Ge ) 227.1(1) pm; R ) Trip, Mo-Ge ) 227.2-
(8) pm)3 and of germylyne complexes, which bear
sterically less demanding and more basic phosphane
ligands, such as trans-[Br(depe)2MotGe-(η1-Cp*)] (Mo-
Ge ) 227.98(5) pm, depe ) Et2PCH2CH2PEt2)11 and
trans-[Cl(PMe3)4MotGe-(η1-Cp*)] ((Mo-Ge)av ) 228.1-
(1) pm (two crystallographically independent molecules
in the solid state)).11 The latter finding can be explained
by the decrease in steric crowding around the metal
center and the stronger molybdenum-germylyne ligand
π bonding in the complexes trans-[Br(depe)2MotGe-
(η1-Cp*)] and trans-[Cl(PMe3)4MotGe-(η1-Cp*)]. Simi-
larly, the W-Ge distances of the germylyne complexes
7a ‚toluene, 7b‚0.5pentane, and 7c‚toluene range from
229.3(1) to 230.60(9) pm (Table 1) and are slightly longer
than that of the dicarbonyl complex [(η5-C5H5)(CO)2Wt
Ge-C6H3-2,6-Mes2] (W-Ge ) 227.7(1) pm),3b but con-
siderably smaller than W-Ge single bond lengths,
which are found between 249 and 268 pm, e.g., (spy-
5-13)-[(η5-Cp*)W(CO)(EtNC)(PMe3)GeCl3] (W-Ge )
249.3(2) pm),25 cis-[(η5-Cp*)W(CO)2{C(H)NEt2}(GeCl3)]
(W-Ge ) 252.69(9) pm),25 [(η5-Cp)2W(GeMe2Cl)(SiMe3)]
(W-Ge ) 254.2(1) pm),26 cis-[(η5-Cp*)W(CO)2(PMe3)-
(GeCl3)] (W-Ge ) 255.90(5) pm),27 W2(GePh3)2(NMe2)4
(W-Ge ) 262.5(1) pm),28 [{(η5-Cp)(CO)3W}2GeCl2] ((W-
Ge)av ) 266.1(1) pm),22c and [(η5-Cp)W(CO)3Ge(C6H3-
2,6-Trip2)] (W-Ge ) 268.1(3) pm).3b Only a small
influence of the metal center and the trans-arranged
halogen ligand is observed on the M-Ge bond lengths
of 4a ,b and 7a -c. For example the W-Ge triple bonds
are approximately 1.7 pm longer than the Mo-Ge triple
bonds (Table 1), this value being close to the difference
of the metallic radii of the two elements (0.8 pm).29
The Μ-Ge-C atom sequences in 4a ,b and 7a -c
deviate slightly from linearity, the angles at the ger-
manium atom ranging from 171.6(2)° to 172.6(2)° (Table
1). The same phenomenon was observed in the dicar-
bonyl complexes [(η5-C5H5)(CO)2MtGe-C6H3-2,6-R2] (M
) Mo, W; R ) Mes, Trip) (Μ-Ge-C ) 170.9(3)-174.3-
(1)°)3 and is apparently in the case of 4a ,b and 7a -c
the result of intramolecular steric repulsions between
the Cp* substituent and the dppe ligands. For example,
the Μ-Ge-C(Cp*) angles of the less crowded germylyne
complexes trans-[Cl(PMe3)4MotGe-(η1-Cp*)] and trans-
[Br(depe)2MotGe-(η1-Cp*)] are 177.3(2)° (mean value
of the two crystallographically independent molecules)
and 177.46(8)°, respectively. These values are close to
the expected 180° for a sp-hybridized germanium atom.
Finally, the Cp* substituent is η1-bonded to germanium,
as evidenced by the Ge-C(1) bond lengths, the Ge-C(2)/
C(5) and Ge-C(3)/C(4) distances, the (C-C)ring bond
lengths, and the bond angles at the C(1) atom (Table
1). For example, the Ge-C(1) bond lengths, which range
from 202.9(5) pm (4b‚0.5pentane) to 204.9(6) pm (7c‚
toluene), compare well with those of Ge-C σ bonds in
other two-coordinate, low-valent germanium compounds,
such as the diarylgermylenes GeMes*2 ((Ge-C)av
)
204.7(4) pm, Mes* ) C6H2-2,4,6-tBu3),30 Ge(C6H3-2,6-
Mes2)2 (Ge-C ) 203.3(4) pm),31 and Ge(C6H3-2,6-(1-
naphthyl)2)2 ((Ge-C)av ) 203.3(2) pm)32 or the dialkyl-
germylene Ge[CH(SiMe3)2][C(SiMe3)3] (Ge-C ) 201.2-
(22) (a) Filippou, A. C.; Winter, J . G.; Kociok-Ko¨hn, G.; Hinz, I. J .
Organomet. Chem. 1997, 542, 35-49. (b) Filippou, A. C.; Winter, J .
G.; Kociok-Ko¨hn, G.; Hinz, I. J . Organomet. Chem. 1997, 544, 225-
231. (c) Filippou, A. C.; Winter, J . G.; Kociok-Ko¨hn, G.; Hinz, I. J .
Chem. Soc., Dalton Trans. 1998, 2029-2036.
(23) Carre´, F.; Colomer, E.; Corriu, R. J . P.; Vioux, A. Organome-
tallics 1984, 3, 970-977.
(24) Chan, L. Y. Y.; Dean, W. K.; Graham, W. A. G. Inorg. Chem.
1977, 16, 1067-1071.
(25) Filippou, A. C.; Portius, P.; Winter, J . G.; Kociok-Ko¨hn, G. J .
Organomet. Chem. 2001, 628, 11-24, and references therein.
(26) Figge, L. K.; Carroll, P. J .; Berry, D. H. Organometallics 1996,
15, 209-215.
(27) Filippou, A. C.; Winter, J . G.; Feist, M.; Kociok-Ko¨hn, G.; Hinz,
I. Polyhedron 1998, 17, 1103-1114.
(28) Chisholm, M. H.; Parkin, I. P.; Huffman, J . C. Polyhedron 1991,
10, 1215-1219.
(29) Pauling, L. The Nature of the Chemical Bond, 3rd ed.; Cornell
University Press: Ithaca, NY, 1960; p 250.
(30) J utzi, P.; Schmidt, H.; Neumann, B.; Stammler, H.-G. Orga-
nometallics 1996, 15, 741-746.
(31) Simons, R. S.; Pu, L.; Olmstead, M. M.; Power, P. P. Organo-
metallics 1997, 16, 1920-1925.
(32) Wegner, G. L.; Berger, R. J . F.; Schier, A.; Schmidbaur, H.
Organometallics 2001, 20, 418-423.

658 Organometallics, Vol. 21, No. 4, 2002
Filippou et al.
F igu r e 4. Structure of one of the two molecules of (η1-
Cp*)GeI3 (8) in the asymmetric unit (DIAMOND plot).
Thermal ellipsoids are drawn at the 50% probability level
and hydrogen atoms omitted for clarity.
F igu r e 5. DIAMOND plot of the molecular structure of
(η1-Cp*)2GeCl2 (9) with thermal ellipsoids drawn at the 50%
probability level. Hydrogen atoms are omitted for clarity.
(6) and 206.7(4) pm).33 This suggests in agreement with
the results of theoretical calculations a high p character
of the germanium hybrid orbital used for the σ bond to
carbon in the germylyne complexes.4 In addition, the
Ge-C(1) bonds of the germylyne complexes are consid-
erably shorter than those of 1a ((Ge-C)av ) 221.7(3)
pm), in which the Cp* group is η2-bonded to germa-
nium.6 Furthermore, the Ge-C(2)/C(5) and Ge-C(3)/
C(4) distances, which lie respectively in the range from
273.8 to 285.0 pm and from 350.3 to 367.4 pm, are too
long to suggest any bonding interaction between these
atoms. Moreover, an alternation of single and double
C-C bonds is observed in the five-membered ring, which
points to localized π bonds between the atoms C(2)-
C(3) and C(4)-C(5), and the germanium atom is dis-
placed beyond the periphery of the five-membered ring,
as shown by the Ge-C(1)-Cg angle, which ranges from
109.4° (7c‚toluene) to 116.9° (7b‚0.5pentane) (Table 1).
The C5 rings are almost planar, the maximal deviation
of one of the ring-carbon atoms from the least-squares
plane is observed in 7a ‚toluene and 7c‚toluene and
ranges from -2.2 pm to 2.4 pm. The C(1)-attached
methyl group is bent out of the ring plane in a direction
away from the germanium atom by 39.4° (7c‚toluene)
to 47.8° (4b‚0.5pentane), which indicates with the other
bond angles at C(1) an sp3 hybridization of this atom.
Finally, similar bonding features are found for the η1-
bonded Cp* group in the germanes (η1-Cp*)GeI3 (8) and
(η1-Cp*)2GeCl2 (9) (vide infra), giving further unambigu-
ous evidence for the η1-bonding mode of the Cp* sub-
stituent in the germylyne complexes 4a ,b and 7a -c.
The molecular structures of 8 and 9 are depicted in
Figures 4 and 5, respectively, and selected bond lengths
and angles are listed in Table 3.
Ta ble 3. Bon d Len gth s (p m ) a n d Bon d An gles
(d eg) w ith Estim a ted Sta n d a r d Devia tion s for
(η1-Cp *)GeI3 (8) a n d (η1-Cp *)2GeCl2 (9)
bond lengths
bond angles
Compound 8a
C(1)-Ge(1)-I(1)
Ge(1)-C(1)
202.8(4)
150.0(5)
135.7(6)
146.6(6)
136.1(6)
151.2(6)
252.7(1)
253.06(8)
254.73(9)
274.7c
112.67(12)
111.90(12)
115.31(13)
108.59(4)
105.91(3)
101.67(3)
106.9
101.2(2)
101.3(3)
108.9(3)
104.2(3)
118.8(4)
119.5(3)
C(1)-C(2)
C(2)-C(3)
C(3)-C(4)
C(4)-C(5)
C(5)-C(1)
Ge(1)-I(1)
Ge(1)-I(2)
Ge(1)-I(3)
Ge(1)‚‚‚C(2)
Ge(1)‚‚‚C(3)
Ge(1)‚‚‚C(4)
Ge(1)‚‚‚C(5)
C(1)-Ge(1)-I(2)
C(1)-Ge(1)-I(3)
I(1)-Ge(1)-I(2)
I(1)-Ge(1)-I(3)
I(2)-Ge(1)-I(3)
b
Ge(1)-C(1)-Cg
Ge(1)-C(1)-C(2)
Ge(1)-C(1)-C(5)
Ge(1)-C(1)-C(6)
C(2)-C(1)-C(5)
C(2)-C(1)-C(6)
C(5)-C(1)-C(6)
342.7c
344.0c
275.7c
Compound 9
Ge-C(1)
C(1)-C(2)
C(2)-C(3)
C(3)-C(4)
C(4)-C(5)
Ge-Cl(1)
Ge‚‚‚C(2)
Ge‚‚‚C(3)
Ge‚‚‚C(4)
Ge‚‚‚C(5)
197.8(5)
153.0(7)
130.2(9)
149.0(7)
134.9(8)
218.61(18)
287.4c
C(1)-Ge-Cl(1)
107.14(15)
106.36(14)
127.3(3)
98.98(11)
120.7
109.4(3)
111.5(4)
108.5(4)
101.7(4)
112.7(5)
113.0(4)
C(1)-Ge-Cl(1)#1
C(1)-Ge-C(1)#1
Cl(1)-Ge-Cl(1)#1
b
Ge-C(1)-Cg
Ge-C(1)-C(2)
Ge-C(1)-C(5)
Ge-C(1)-C(6)
C(2)-C(1)-C(5)
C(2)-C(1)-C(6)
C(5)-C(1)-C(6)
369.3c
369.2c
290.0c
a
Bond lengths and angles of one of the two independent
b
molecules. Cg denotes the center of the C5 ring. c Atomic dis-
tances.
C(1)-Ge-C(1)#1 angle of 9 (127.3(3)°), which are more
obtuse than that of a regular tetrahedron. These distor-
tions can be explained with the large steric demand of
the Cp* group, to which an electronic effect is super-
imposed according to the Walsh/Bent rules.34 For the
same reasons the Ge-I bonds of 8 ((Ge-I)av ) 253.37-
(9) pm) are longer than those of GeI4 ((Ge-I)av ) 250.0-
(1) pm),35 the Ge-Cl bonds of 9 (218.61(18) pm) are
longer than those of GeCl4 (211.3(3) pm),36 MeGeCl3
(213.2(3) pm),37 (η1-Cp*)GeCl3 ((Ge-Cl)av ) 213.41(7)
Two independent molecules of 8 with marginally
different bonding parameters were found in the asym-
metric unit. The following discussion is based on the
average bond lengths and angles of the two molecules
of 8. Compound 9 reveals a crystallographically imposed
C2 symmetry. Both halogermanes are composed of
distorted tetrahedral molecules, as revealed by the
I-Ge-I angles of 8 (105.74(3)°, mean value) and the
Cl(1)-Ge-Cl(1)#1 angle of 9 (98.98(11)°), which are
more acute than that of a regular tetrahedron, or the
C-Ge-I angles of 8 (112.98(12)°, mean value) and the
(34) (a) Walsh, A. D. J . Chem. Soc. 1948, 398-406. (b) Bent, H. A.
Chem. Rev. 1961, 61, 275-311.
(35) Walz, L.; Thiery, D.; Peters, E.-M.; Wendel, H.; Scho¨nherr, E.;
Wojnowski, M. Z. Kristallogr. 1993, 208, 207-211.
(36) Morino, Y.; Nakamura, Y.; Iijima, T. J . Chem Phys. 1960, 32,
643-652.
(33) J utzi, P.; Becker, A.; Stammler, H.-G.; Neumann, B. Organo-
metallics 1991, 10, 1647-1648.
(37) Drake, J . E.; Hencher, J . L.; Shen, Q. Can. J . Chem. 1977, 55,
1104-1110.

Molybdenum and Tungsten Germylyne Complexes
Organometallics, Vol. 21, No. 4, 2002 659
pm),11 and Me2GeCl2 (214.3(4) pm),37 and the Ge-C
bonds of 9 (197.8(5) pm) (Table 3) are slightly longer
than that of (η1-Cp*)GeCl3 (196.3(3) pm).11
an external 85% aqueous H3PO4 solution. The following
abbreviations were used for the signal multiplicities: s )
singlet, m ) multiplet. Melting points were determined using
a Bu¨chi 530 melting point apparatus and are corrected. The
samples were sealed under vacuum in capillary tubes.
Con clu sion
1. P r ep a r a t ion of Cp *GeCl (1a ) a n d [Cp *Ge][GeCl3]
(2a ) fr om GeCp *2 a n d GeCl2(1,4-d ioxa n e). A solution of
GeCp*2 (1.647 g, 4.801 mmol) in 40 mL of CH2Cl2 was cooled
to -70 °C and added without stirring to a suspension of GeCl2-
(1,4-dioxane) (1.123 g, 4.848 mmol) in 35 mL of CH2Cl2, which
was kept at -70 °C. Stirring was then started, and the reaction
mixture was allowed to warm to ambient temperature within
approximately 0.5 h. During this time all GeCl2(1,4-dioxane)
dissolved and a slight cloudy, pale yellow-green solution
resulted. After stirring for 10 min at ambient temperature the
solvent was removed in vacuo, and the residue was dried
briefly and extracted three times with 60 mL of pentane. The
combined pentane extracts were evaporated to dryness to
afford 1a as a pale green-yellow, microcrystalline solid of
characteristic smell, which can be stored for several months
in the freezer (-28 °C) without sign of decomposition: yield
2.094 g (90% based on GeCp*2); mp 76 °C. 1H NMR (300 MHz,
C6D6): δ 1.65 (s, 15H, C5Me5). 1H NMR (300 MHz, toluene-
d8): δ 1.66 (s, 15H, C5Me5). 1H NMR (300 MHz, THF-d8): δ
Thermal elimination of dinitrogen from the complexes
trans-[M(dppe)2(N2)2] (M ) Mo, W; dppe ) Ph2PCH2-
CH2PPh2) affords in the presence of the germanium(II)
halides (Cp*GeX)n (Cp* ) C5Me5; X ) Cl, n ) 1; X )
Br, n ) 2; X ) I, n ) ∞) the mononuclear germylyne
complexes trans-[X(dppe)2MtGe-(η1-Cp*)]. The spec-
troscopic data and the structural parameters provide
experimental evidence for the presence of metal-
germanium triple bonds in these complexes. The large
number of known transition metal dinitrogen com-
plexes38 and the increasing number of isolable germa-
nium(II) halides39 let us suggest that the “dinitrogen
elimination method” can become a very valuable route
to germylyne complexes of variable ligand sphere al-
lowing systematic reactivity studies. Preliminary work
in this direction shows that the “dinitrogen elimination
method” can be also used to prepare germylyne com-
plexes bearing monodentate phosphane ligands, e.g.,
trans-[Cl(PMe3)4MtGe-(η1-Cp*)] (M ) Mo, W), which
easily undergo oxidation reactions. Halogen exchange
by pseudohalides is also possible in the case of tungsten
to afford the germylyne complexes trans-[Y(dppe)2Wt
Ge-(η1-Cp*)] (Y ) NCO, N3, NCS, CN).11
1
2.00 (s, 15H, C5Me5). H NMR (300 MHz, CD2Cl2): δ 2.02 (s,
15H, C5Me5). 13C{1H} NMR (75.5 MHz, C6D6): δ 9.4 (s, C5Me5),
120.1 (s, C5Me5). 13C{1H} NMR (75.5 MHz, toluene-d8): δ 9.3
(s, C5Me5), 120.2 (s, C5Me5). 13C{1H} NMR (75.5 MHz, CD2-
Cl2): δ 9.8 (s, C5Me5), 120.7 (s, C5Me5).
The pentane-insoluble fraction was treated with CH2Cl2, and
the solution was filtered from some insoluble yellow material.
The filtrate was concentrated in vacuo to a few milliliters and
treated with a diethyl ether/pentane mixture (1/1) to complete
precipitation of 2a as a white solid, which was dried in vacuo
at ambient temperature: yield 167 mg (5% relative to GeCp*2).
1H NMR (300 MHz, CD2Cl2): δ 2.16 (s, 1J (C,H) ) 129.4 Hz,
15H, C5Me5). 13C{1H} NMR (75.5 MHz, CD2Cl2): δ 9.6 (s,
C5Me5), 121.7 (s, C5Me5).
Exp er im en ta l Section
Gen er a l P r oced u r es. All experiments were carried out
under an atmosphere of argon using Schlenk and glovebox
techniques.40 The solvents were dried by standard methods
(pentane over CaH2, toluene, THF, and diethyl ether over Na/
benzophenone, CH2Cl2 over Sicapent (Merck) and Na/Pb alloy)
and distilled under dinitrogen. The dried solvents were stored
over LiAlH4 (toluene and CH2Cl2 over CaH2), trap-to-trap
condensed, and deoxygenated immediately prior to use. The
dinitrogen complexes 3 and 5 were prepared as reported in
the literature8 under an atmosphere of dinitrogen and recrys-
tallized from THF, until the compounds were found by
elemental analysis to be free of chlorine. Cp*GeI (1c) was
prepared upon treatment of 1a with an excess of NaI in diethyl
ether,11 Cp*GeI3 (8)41 upon oxidation of 7c with iodine, and
Cp*2GeCl2 (9) as described previously.42 Elemental analyses
were obtained from the Central Analytical Group of the
Chemistry Department of the Humboldt-Universita¨t zu Berlin.
Solution IR spectra were recorded in the region 2300-1500
cm-1 on a Bruker IFS-55 spectrometer and IR spectra of the
products in the region 4000-400 cm-1 as KBr pellets. 1H, 13C-
{1H}, and 31P{1H} NMR spectra were recorded on a Bruker
AM-300 spectrometer in dry deoxygenated tetrahydrofurane-
d8, benzene-d6, toluene-d8, or methylene-d2 chloride. The 1H
and 13C{1H} NMR spectra were calibrated against the internal
residual proton and natural abundance 13C resonances of the
deuterated solvent (tetrahydrofurane-d8, δH 1.73 and δC 25.3
ppm; benzene-d6, δH 7.15 and δC 128.0 ppm; toluene-d8, δMe
2.09 and δMe 20.4 ppm; methylene-d2 chloride δH 5.32 and δC
53.8 ppm). The 31P{1H} NMR spectra were calibrated against
2. P r ep a r a tion of Cp *GeBr (1b) a n d [Cp *Ge][GeBr 3]
(2b) fr om GeCp *2 a n d GeBr 2(1,4-d ioxa n e). A sample of
GeCp*2 (423 mg, 1.23 mmol) was mixed at -78 °C with a
sample of GeBr2(1,4-dioxane) (415 mg, 1.29 mmol), and
the mixture was treated with 20 mL of cold (-78 °C) tolu-
ene. The suspension was stirred and allowed to warm to
room temperature. After stirring for 0.5 h at ambient temper-
ature an orange suspension resulted, which was evaporated
to dryness and dried in vacuo for 1 h. The residue was
extracted twice with 50 mL of pentane and the insoluble
portion worked up as described below. The combined pentane
extracts were concentrated under vacuum to approximately 5
mL, and the resulting suspension was cooled to -78 °C to
complete crystallization of 1b. The supernatant solution was
decanted and the precipitate was dried for 0.5 h in vacuo at
ambient temperature to afford 1b as a white, microcrystalline
solid: yield 621 mg (88% based on GeCp*2). 1H NMR (300
1
1
MHz, C6D6): δ 1.65 (s, J (C,H) ) 127.1 Hz, 15H, C5Me5). H
NMR (300 MHz, toluene-d8): δ 1.66 (s, 15H, C5Me5). 1H NMR
(300 MHz, CD2Cl2): δ 2.00 (s, 15H, C5Me5). 13C{1H} NMR
(75.5 MHz, C6D6): δ 9.6 (s, C5Me5), 119.9 (s, C5Me5). 13C{1H}
NMR (75.5 MHz, toluene-d8): δ 9.5 (s, C5Me5), 120.0 (s, C5-
Me5). 13C{1H} NMR (75.5 MHz, CD2Cl2): δ 9.9 (s, C5Me5), 120.1
(s, C5Me5).
The pentane-insoluble fraction was treated with CH2Cl2, and
the solution was filtered from some insoluble orange material.
The colorless filtrate was concentrated in vacuo to a few
milliliters and treated with pentane to complete precipitation
of 2b . The precipitate was washed with pentane and dried
under vacuum for 1 h to afford 2b as a muddy-white solid:
yield 72 mg (6% based on GeCp*2); mp 134-140 °C. Anal.
Calcd for C10H15Br3Ge2 (520.18): C, 23.09; H, 2.91; Br, 46.08.
Found: C, 23.16; H, 3.12; Br, 45.81. 1H NMR (300 MHz,
(38) Hidai, M.; Mizobe, Y. Chem. Rev. 1995, 95, 1115-1133, and
references therein.
(39) Stender, M.; Pu, L.; Power, P. P. Organometallics 2001, 20,
1820-1824, and references therein.
(40) Shriver, D. F.; Drezdzon, M. A. The Manipulation of Air-
Sensitive Compounds, 2nd ed.; Wiley: New York, 1986.
(41) J utzi, P.; Hampel, B.; Organometallics 1986, 5, 730-734.
(42) J utzi, P.; Hielscher, B. Organometallics 1986, 5, 1201-1204.

660 Organometallics, Vol. 21, No. 4, 2002
Filippou et al.
1
1
C6D6): δ 1.41 (s, J (C,H) ) 129.2 Hz, 15H, C5Me5). H NMR
(300 MHz, CD2Cl2): δ 2.17 (s, 1J (C,H) ) 129.3 Hz, 15H, C5Me5).
13C{1H} NMR (75.5 MHz, C6D6): δ 8.9 (s, C5Me5), 120.6 (s, C5-
Me5). 13C{1H} NMR (75.5 MHz, CD2Cl2): δ 9.8 (s, C5Me5), 121.8
(s, C5Me5).
in 5 mL of toluene was added to a solution of 6 (184 mg, 0.177
mmol) in 40 mL of toluene, and the mixture was heated in a
preheated oil bath (120 °C), so that the solvent boiled gently.
The color of the solution turned from orange to red, and after
40 min an IR spectrum of the reaction solution was recorded,
confirming the absence of any N2-containing complexes. The
solution was then concentrated in vacuo to a few milliliters
and cooled overnight at -28 °C. The resulting suspension was
treated with 30 mL of cold pentane (-28 °C) to complete
precipitation of complex 7b‚toluene, which was washed with
10 mL of pentane and dried under fine vacuum for 3 h at
ambient temperature. An orange-brown solid resulted, yield
188 mg (78%), mp 236 °C (dec). Anal. Calcd for C69H71BrGeP4W
(1360.58): C, 60.91; H, 5.26; Br, 5.87. Found: C, 60.25; H, 5.37;
Br, 6.49. 1H NMR (300 MHz, THF-d8, RT): δ 1.37 (s, 15H,
C5Me5), 2.31 (s, 3H, PhMe), 2.46 (m, 4H, 4 × HACHB), 2.95 (m,
4H, 4 × HACHB), 6.89-7.70 (m, 45H, 4 × PPh2 and PhMe).
1H NMR (300 MHz, C6D6, RT): δ 1.47 (s, 15H, C5Me5), 2.10 (s,
3H, PhMe), 2.40 (m, 4H, 4 × HACHB), 2.93 (m, 4H, 4 × HACHB),
6.98-7.81 (m, 45 H, 4 × PPh2 and PhMe). 31P{1H} NMR (121.5
MHz, THF-d8, RT): δ 43.9 (s, 1J (W,P) ) 262.3 Hz).31P{1H}
NMR (121.5 MHz, C6D6, RT): δ 45.9 (s, 1J (W,P) ) 262.6
Hz).13C{1H} NMR (75.5 MHz, THF-d8, 220K): δ 12.7 (s,
C5Me5), 21.6 (s, PhMe), 37.4 (m, 4 × CH2), 126.2 (s, p-C, PhMe),
127.1 (s, C5Me5), 128.1 (m, m-C, 4 × PhAPPhB), 128.5 and 129.3
(s, p-C, 4 × PhAPPhB), 129.1 (s, m-C, PhMe), 129.8 (s, o-C,
PhMe), 134.6 and 135.5 (m, o-C, 4 × PhAPPhB), 138.4 (s, ipso-
C, PhMe), 138.7 and 148.7 (m, ipso-C, 4 × PhAPPhB).
3. P r ep a r a tion of tr a n s-[Cl(d p p e)2MotGe-(η1-Cp *)]‚
tolu en e (4a ‚tolu en e). A mixture of 3 (385 mg, 0.406 mmol)
and Cp*GeCl (1a ) (100 mg, 0.411 mmol) was suspended in 80
mL of toluene, and the suspension was refluxed for 20 min.
During this time all starting material dissolved to give an
orange solution, which turned rapidly dark red to red-brown.
Completion of the reaction was confirmed by IR and 31P{1H}
NMR spectroscopy. The warm solution was filtered and the
filtrate concentrated in vacuo to approximately 3 mL and
cooled to -28 °C for 1 h to afford a precipitate, which was
washed with a minimum amount of cold toluene and dried in
vacuo. The solid was redissolved in hot toluene, the solution
was filtered, and the filtrate was concentrated to a few
milliliters and cooled to -28 °C. The resulting precipitate was
washed with a minimum amount of cold toluene and recrystal-
lized from toluene as described above to yield after drying
under fine vacuum at ambient temperature 4a ‚toluene as an
analytically pure orange-brown, microcrystalline solid: yield
200 mg (40%); mp 237 °C (dec). Anal. Calcd for C69H71
ClGeMoP4 (1228.22): C, 67.48; H, 5.83; Cl, 2.89; N, 0. Found:
C, 67.90; H, 5.87; Cl, 3.13; N, 0.00. H NMR (300 MHz, THF-
-
1
d8, RT): δ 1.41 (s, 15H, C5Me5), 2.31 (s, 3H, PhMe), 2.45 (m,
4H, 4 × HACHB), 2.83 (m, 4H, 4 × HACHB), 6.84-7.70 (m, 45H,
1
4 × PPh2 and PhMe). H NMR (300 MHz, C6D6, RT): δ 1.50
6. P r epar ation of tr a n s-[I(dppe)2WtGe(η1-Cp*)]‚tolu en e
(7c‚tolu en e). A Schlenk tube was charged with 6 (214 mg,
0.206 mmol) and Cp*GeI (1c) (77 mg, 0.23 mmol), and the
mixture was suspended in 30 mL of toluene. The suspension
was heated in a preheated oil bath (120 °C), so that the solvent
boiled gently. On heating the reaction mixture all starting
material dissolved to give an orange solution, which turned
gradually to red. IR monitoring of the reaction revealed a
continuous decrease in intensity of the ν(N2) absorptions of 5
at 2010 and 1949 cm-1. After approximately 20 min the color
of the solution had changed to dark red and complex 5 had
been completely consumed (IR detection). The reaction mixture
was allowed to cool to ambient temperature and filtered from
some dark brown insoluble material, and the filtrate was
concentrated in vacuo to approximately 4 mL and cooled to
-78 °C. The supernatant solution was decanted and the
precipitate was washed with 10 mL of pentane at -78 °C and
dried under high vacuum at room temperature overnight to
afford 7c‚toluene as a red-brown powder: yield 189 mg (65%),
mp 221 °C (dec). Anal. Calcd for C69H71GeIP4W (1407.58): C,
58.88; H, 5.08; N, 0; I, 9.02. Found: C, 58.79; H, 5.20; N, 0.00;
I, 9.23. 1H NMR (300 MHz, THF-d8, RT): δ 1.31 (s, 15H,
C5Me5), 2.31 (s, 3H, PhMe), 2.54 (m, 4H, 4 × HACHB), 3.09 (m,
4H, 4 × HACHB), 6.89-7.72 (m, 45H, 4 × PPh2 and PhMe).
1H NMR (300 MHz, C6D6, RT): δ 1.40 (s, 15H, C5Me5), 2.10 (s,
PhMe), 2.46 (m, 4H, 4 × HACHB), 3.07 (m, 4H, 4 × HACHB),
6.98-7.84 (m, 45H, 4 × PPh2 and PhMe). 31P{1H} NMR (121.5
MHz, THF-d8, RT): δ 38.7 (s, 1J (W,P) ) 258.8 Hz). 31P{1H}
(s, 15H, C5Me5), 2.10 (s, PhMe), 2.37 (m, 4H, 4 × HACHB), 2.81
(m, 4H, 4 × HACHB), 6.88-7.81 (m, 45H, 4 × PPh2 and PhMe).
31P{1H} NMR (121.5 MHz, THF-d8, RT): δ 66.6 (s). 31P{1H}
NMR (121.5 MHz, C6D6, RT): δ 66.7 (s). 13C{1H} NMR (75.5
MHz, THF-d8, RT): 12.7 (s, C5Me5), 21.5 (s, PhMe), 33.3 (m, 4
× CH2), 126.0 (s, p-C, PhMe), 126.9 (s, C5Me5), 127.3 and 128.1
(m, m-C, 4 × PhAPPhB), 128.2 and 129.0 (s, p-C, 4 × PhAPPhB),
128.9 (s, m-C, PhMe), 129.6 (s, o-C, PhMe), 134.5 and 135.2
(m, o-C, 4 × PhAPPhB), 138.4 (s, ipso-C, PhMe), 138.9 and 147.1
(m, ipso-C, 4 × PhAPPhB).
4. P r ep a r a tion of tr a n s-[Br (d p p e)2MotGe-(η1-Cp *)]‚
tolu en e (4b‚tolu en e). A mixture of 3 (340 mg, 0.358 mmol)
and Cp*GeBr (1b) (103 mg, 0.358 mmol) was suspended in 50
mL of toluene, and the suspension was refluxed for 7 min in
the glovebox. During this time all starting material dissolved
to give an orange solution, which turned rapidly to red-brown.
Completion of the reaction was confirmed by IR and 31P{1H}
NMR spectroscopy. The warm solution was filtered and the
filtrate concentrated in vacuo to a few milliliters and cooled
for 1 h at -28 °C to afford a precipitate, which was washed
with cold toluene and dried in vacuo at ambient temperature
for 0.5 h. The dark orange solid was recrystallized three times
from hot toluene as described above for the isolation of 4a ‚
toluene to afford complex 4b‚toluene as an orange-brown,
microcrystalline solid: yield 82 mg (18%); mp 224 °C (dec).
Anal. Calcd for C69H71BrGeMoP4 (1272.68): C, 65.12; H, 5.62;
1
Br, 6.28; N, 0. Found: C, 65.65; H, 6.03; Br, 6.72; N, 0.00. H
NMR (300 MHz, THF-d8, RT): δ 1.36 (s, 15H, C5Me5), 2.31 (s,
3H, PhMe), 2.49 (m, 4H, 4 × HACHB), 2.93 (m, 4H, 4 × HACHB),
6.86-7.73 (m, 45H, 4 × PPh2 and PhMe). 1H NMR (300 MHz,
C6D6, RT): δ 1.46 (s, 15H, C5Me5), 2.10 (s, PhMe), 2.42 (m,
4H, 4 × HACHB), 2.91 (m, 4H, 4 × HACHB), 6.89-7.84 (m, 45H,
4 × PPh2 and PhMe). 31P{1H} NMR (121.5 MHz, THF-d8,
RT): δ 64.9 (s). 31P{1H} NMR (121.5 MHz, C6D6, RT): δ 65.0
(s). 13C{1H} NMR (75.5 MHz, THF-d8, RT): 12.7 (s, C5Me5),
21.5 (s, PhMe) 33.9 (m, 4 × CH2), 126.0 (s, p-C, PhMe), 126.9
(s, C5Me5), 127.1 and 128.2 (m, m-C, 4 × PhAPPhB), 128.3 and
129.0 (s, p-C, 4 × PhAPPhB), 128.9 (s, m-C, PhMe), 129.6 (s,
o-C, PhMe), 134.4 and 135.4 (m, o-C, 4 × PhAPPhB), 138.4 (s,
ipso-C, PhMe), 139.2 and 147.9 (m, ipso-C, 4 × PhAPPhB).
5. P r ep a r a tion of tr a n s-[Br (d p p e)2WtGe-(η1-Cp *)]‚
tolu en e (7b‚tolu en e). A solution of 1b (51 mg, 0.177 mmol)
1
NMR (121.5 MHz, C6D6, RT): δ 40.6 (s, J (W,P) ) 258.0 Hz).
13C{1H} NMR (75.5 MHz, THF-d8, RT): 12.6 (s, C5Me5), 21.5
(s, PhMe), 38.4 (m, 4 × CH2), 126.0 (s, p-C, PhMe), 127.0 (s,
C5Me5), 126.8 and 128.4 (m, m-C, 4 × PhAPPhB), 128.0 and
129.1 (s, p-C, 4 × PhAPPhB), 128.9 (s, m-C, PhMe), 129.6 (s,
o-C, PhMe), 134.6 and 135.6 (m, o-C, 4 × PhAPPhB), 138.4 (s,
ipso-C, PhMe), 140.7 and 149.9 (m, ipso-C, 4 × PhAPPhB).
7. Cr ysta l Str u ctu r e Deter m in a tion of 4a ‚0.5p en ta n e,
4b‚0.5p en ta n e, 7b‚0.5p en ta n e, 7c‚tolu en e, 8, a n d 9. A
summary of the crystal data, data collection, and refinement
is given in Table 4.
The data collection of 8 and of the solvates of 4a , 4b, and
7c was performed on a STOE IPDS diffractometer (area

Molybdenum and Tungsten Germylyne Complexes
Organometallics, Vol. 21, No. 4, 2002 661
Ta ble 4. Su m m a r y of Cr ysta llogr a p h ic Da ta of th e Com p ou n d s 4a ‚0.5p en ta n e, 4b‚0.5p en ta n e,
7b‚0.5p en ta n e, 7c‚tolu en e, 8, a n d 9
4a ‚0.5pentane
4b‚0.5pentane
7b.0.5pentane
7c‚toluene
8
9
empirical
formula
C
64.5H69ClGeMoP4
C64.5H69BrGeMoP4
C64.5H69BrGeP4W
C69H71GeIP4W
C10H15GeI3
C20H30Cl2Ge
Mt
1172.06
dark red
0.24 × 0.20 ×
0.16
1216.52
dark red
0.52 × 0.30 ×
0.20
1304.43
dark red
0.36 × 0.32 ×
0.20
1407.48
red-brown
0.24 × 0.16 ×
0.08
588.51
red
413.93
cryst color
cryst size (mm)
pale yellow
0.34 × 0.23 ×
0.02
0.64 × 0.44 ×
0.24
temp (K)
cryst syst
space group
a (Å)
b (Å)
c (Å)
180(2)
180(2)
180(2)
180(2)
180(2)
183(2)
monoclinic
I2/a (no. 15)
24.664(4)
13.3460(16)
34.453(5)
90
97.322(18)
90
11248(3)
8
monclinic
I2/a (no. 15)
24.715(5)
13.2501(19)
34.527(7)
90
97.68(2)
90
11205(3)
8
monoclinic
C2/c (no. 15)
39.57(3)
13.225(8)
34.48(4)
90
141.95(4)
90
11121(16)
8
triclinic
P1h (no. 2)
10.592(2)
16.287(3)
17.928(3)
97.24(2)
96.58(2)
103.31(2)
2952.8(10)
2
triclinic
P1h (no. 2)
8.376(2)
13.524(4)
13.774(3)
89.35(3)
82.45(3)
89.67(3)
1546.7(7)
4
monoclinic
C2/c (no. 15)
14.986(3)
8.9304(12)
16.878(4)
90
112.20(2)
90
2091.4(7)
4
R (deg)
â (deg)
γ (deg)
V (Å3)
Z
Fcalcd (g‚cm-3
)
)
1.384
0.959
4856
1.442
1.628
5000
1.558
3.482
5256
1.583
3.128
1408
2.527
7.938
1064
1.315
1.718
864
µ
MoKR (mm-1
F(000)
2θ min/max
(deg)
4.3/50.5
4.3/49.8
3.3/52.0
4.6/50.5
5.4/50.5
5.2/52.0
hkl range
-29, 29/-16,
16/-41, 41
36 274
-29, 28/-15,
15/-40, 40
96 78
-48, 48/0,
16/-42, 42
18 487
-12, 12/-19,
19/-21, 21
19 795
-10, 10/-16,
16/-16, 16
13 610
-18, 17/-10,
10/0, 20
2048
total no. of data
no. of unique
data (I > 2σI)
R(int)
10 154
9678
10 919
10 062
5191
2048
0.0875
0.1226
0.0695
0.0528
0.0420
0.0867
abs corr
min./max.
none
0.932/-0.759
numerical
0.787/-0.822
empirical
1.187/-0.899
numerical
1.541/-2.004
refdelf
0.923/-0.723
empirical
0.768/-0.688
density (e‚Å-3
no. of params
refined
)
651
650
632
686
254
106
a
R1 (I > 2σI)
0.0405
0.0983
0.929
0.0403
0.0872
0.819
0.0491
0.1107
1.089
0.0413
0.0936
0.947
0.0255
0.0651
1.024
0.0624
0.1754
0.785
b
wR2 (all data)
GOFc
R1 ) ∑||Fo| - |Fc||/∑|Fo|. wR2) {∑[w(Fo - Fc2)2]/∑[w(Fo2)2]}1/2
.
c GOF ) S ) {∑[w(Fo - Fc2)2]/(n - p)}1/2
.
a
b
2
2
detector), whereas data of 7b‚0.5pentane43 and 9 were collected
on a STOE STADI-4 diffractometer (scintillation counter) with
Mo KR radiation (λ ) 0.71073 Å). Both diffractometers were
equipped with a low-temperature device. An absorption cor-
rection was applied in all cases instead of 4a ‚0.5pentane.44 The
data of 4b‚0.5pentane and 7c‚toluene were treated by a
numerical absorption correction. The crystal of 4b‚0.5pentane
was optimized by the program XSHAPE1.02, whereas in 7c‚
toluene the crystal faces were indexed with a microscope on
the diffractometer before the numerical absorption correction
was applied that is based on a Gaussian algorithm and
implemented in XRED1.08.45 The data of 7b‚pentane, 8 (ψ-
scan each),46 and 9 (“refdelf”)47 were corrected empirically. The
structure solution and refinement was carried out following
standard methods (SHELXS97 and SHELXL97).48 Hydrogen
refined anisotropically except the n-pentane carbon atoms in
7b‚0.5pentane. In the structure of 7b‚0.5pentane the pentane
molecule could be localized only after absorption correction.
A split atom model could not be applied successfully for 9 (C(3),
C(4), C(8), and C(9) atoms were split, wR2 ) 0.1957). Geo-
metrical calculations were performed with PLATON49 and
illustrations with DIAMOND.50
Ack n ow led gm en t. We thank the Humboldt Uni-
versita¨t zu Berlin and the Fonds der Chemischen
Industrie for financial support of this work, Dr. B.
Ziemer, Dr. G. Kociok-Ko¨hn, and P. Neubauer for the
single-crystal X-ray diffraction studies, Dr. U. Hart-
mann, U. Kursawe, and U. Ka¨tel for the elemental
analyses, and Dr. J . G. Winter for a sample of 9.
atoms were calculated at idealized positions (“AFIX”, D(Caliph
H) ) 98 pm, D(Car-H) ) 95 pm). All non-hydrogen atoms were
-
Su p p or tin g In for m a tion Ava ila ble: Further details of
the crystal structure determinations including tables of crystal
data and structure refinement, atomic coordinates, bond
lengths, bond angles, and thermal parameters for 4a ‚0.5pen-
tane, 4b‚0.5pentane, 7b‚0.5pentane, 7c‚toluene, 8, and 9. This
material is available free of charge via the Internet at
http://pubs.acs.org.
(43) A mixture of pentane isomers was used for the crystallizations.
Only n-pentane was found in all hemipentane solvates.
(44) Programs for data collection, cell refinement, and data reduction
and correction: IPDS-2.87, STADI4-1.06, XRED-1.08, and XSHAPE-
1.02, Stoe&Cie: Darmstadt, Germany, 1997.
(45) More than 200 strong reflections with 4 symmetry equivalents
in each case were used for the optimization of 4b‚0.5pentane. XSHAPE
is based on the program HABITUS (Herrendorf, W. PhD Thesis,
Universita¨t Karlsruhe, Germany, 1993).
OM010785X
(46) North, A. C. T.; Phillips, D. C.; Mathwes, F. S. Acta Crystallogr.
A 1968, 24, 351-359.
(47) Walker, N.; Stuart, D. Acta Crystallogr. A 1983, 39, 158-166.
(48) (a) Sheldrick, G. M. Acta Crystallogr. A 1990, 46, 467-473. (b)
Sheldrick, G. M. (SHELXL; Universita¨t Go¨ttingen: Germany, 1997.
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