Activation of aryl germanium(II) chlorides by [Mo(PMe3) 6] and [W(η2-CH2PMe2)H(PMe 3)4]: A new route to metal-germanium triple bonds

Article abstract of DOI:10.1002/anie.200602061

(Chemical Equation Presented) A new activation mode of aryl germanium(II) chlorides at electron-rich metal centers leads to compounds featuring metal-germanium triple bonds. Reaction of 1 with RGeCl affords the hydridogermylidene complex 2, which rearranges thermally to give the germylidyne complex 3 (see scheme; Trip = C₆H₂-2,4,6-iPr ₃). In contrast, the reaction of [Mo(PMe₃)₆] with RGeCl yields directly the germylidyne complex trans-[CI(PMe ₃)₄Mo≡GeR].

Full text of DOI:10.1002/anie.200602061

Angewandte
Chemie
Germylidyne Complexes
DOI: 10.1002/anie.200602061
Activation of Aryl Germanium(II) Chlorides by
[Mo(PMe3)6] and [W(h2-CH2PMe2)H(PMe3)4]: A
New Route to Metal–Germanium Triple Bonds**
Alexander C. Filippou,* Nils Weidemann,
Athanassios I. Philippopoulos, and
Gregor Schnakenburg
Homoleptic trimethylphosphane complexes of transition
metals, such as [Mo(PMe3)6] (2-Mo)[1] and [W(PMe3)6] (2-
W),[2] form a class of rare and very reactive compounds.[3–5]
The high reactivity of these complexes originates from the
combination of strong s-donor and weak p-acceptor proper-
ties of the PMe3 ligand, which leads to very electron-rich
metal centers[6] that are capable of activating s bonds. A
consequence of the high reactivity of the metal centers and
the steric pressure caused by the PMe3 ligands in the
complexes [M(PMe3)6] (M = Mo, W) is the facile dissociation
À
of one PMe3 ligand to afford, through an intramolecular C H
bond activation, the cyclometalated products [M(h2-
CH2PMe2)H(PMe3)4].[1,2] The complexes [M(PMe3)6] and
their cyclometalation products are subject to various ligand
displacement and oxidative addition reactions.[7] We report
here a new reaction type of these electron-rich metal
À
complexes that involves a Ge Cl bond heterolysis of an aryl
germanium(II) chloride to form metal–germanium triple
bonds.
A new method was developed for the synthesis of the
starting materials [Mo(PMe3)6] (2-Mo) and [W(h2-
CH2PMe2)H(PMe3)4] (2-W-c) involving the reduction of
trans-[MCl2(PMe3)4] (1-M; M = Mo, W)[8,9] with sodium
[*] Prof. Dr. A. C. Filippou, G. Schnakenburg
Institut für Anorganische Chemie
Rheinische Friedrich-Wilhelms-Universität Bonn
Gerhard-Domagk-Strasse 1, 53121 Bonn (Germany)
Fax: (+49)228-73-5327
E-mail: filippou@uni-bonn.de
N. Weidemann
Institut für Chemie
Humboldt-Universität zu Berlin
Brook-Taylor Strasse 2, 12489 Berlin (Germany)
Dr. A. I. Philippopoulos
Institute of Physical Chemistry
NCSR Demokritos
Ag. Paraskevi Attikis, 15310 Athens (Greece)
[**] We are grateful to the Humboldt-Universität zu Berlin and the
Deutsche Forschungsgemeinschaft (project FI 445/6-1) for the
generous financial support of this work, Dr. B. Ziemer and P.
Neubauer for technical assistance with the X-ray diffraction studies,
Dr. U. Hartmann and U. Kätel for the elemental analyses, and Dr. C.
Mügge, W.-D. Bloedorn, A. Thiesies, C. Schmidt, and K. Prochnicki
for NMR experiments. N.W. thanks the Fonds der Chemischen
Industrie for a fellowship.
Supporting information for this article is available on the WWW
under http://www.angewandte.org or from the author.
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powder in THF in the presence of excess PMe3.[10] This
pose upon melting at 1428C (4-Mo-Cl) and 1848C (4-W-Cl).
The hydrido–germylidene complex 5-W-Cl can be stored for a
few hours at room temperature. However, its green solutions
in toluene or pentane turn gradually brown at ambient
temperature as a result of formation of 4-W-Cl. The molecular
structure of 4-W-Cl was determined by single-crystal X-ray
diffraction and exhibits an octahedral complex of roughly C2v
symmetry in which the germylidyne and the chlorido ligands
are in a trans arrangement (Ge-W-Cl 179.3(1)8, Figure 1).[10,16]
method offers several advantages compared to the published
methods.[1,7a,b,11] Complex 2-Mo was thereby obtained as a
beige solid in about 60% yield,[12] and complex 2-W-c as a
bright yellow, very air-sensitive solid in 93% yield. Complex
2-Mo reacts with one equivalent of the aryl germanium(II)
chloride Ge(C6H3-2,6-Trip2)Cl (3; Trip = C6H2-2,4,6-iPr3)[13] in
toluene to give selectively upon elimination of two PMe3
ligands the germylidyne complex 4-Mo-Cl, which was isolated
as a brown, air-sensitive, crystalline solid in 67% yield
[Eq. (1)].[10] No intermediates were observed in this reaction,
which is complete within two hours at room temperature.[14]
In contrast, treatment of 2-W-c with one equivalent of 3 in
pentane at À208C afforded selectively a thermolabile, very
air-sensitive, green product, which was identified by X-ray
crystallography and NMR spectroscopy to be the tungsten(II)
hydrido–germylidene complex 5-W-Cl (Scheme 1).[10] Con-
Figure 1. DIAMOND plot of the molecular structure of 4-W-I in the
solid state. Thermal ellipsoids are set at the 30% probability level.
Hydrogen atoms are omitted for clarity. Selected bond lengths [Š] and
bond angles [8] of 4-W-I [values for 4-W-Cl are given in square
brackets]: W-Ge 2.3206(4) [2.338(1)], W-I 2.8797(5) [W-Cl 2.540(3)], W-
P1 2.4711(8) [2.473(4)], W-P2 2.4967(8) [2.498(4)], W-P3 2.4888(8)
[2.473(3)], W-P4 2.4883(8) [2.477(4)], Ge-C1 2.004(2) [1.982(10)]; W-
Ge-C1 175.79(7) [177.9(3)], Ge-W-I 177.592(9) [Ge-W-Cl 179.3(1)], Ge-
W-P1 90.81(2) [92.55(9)], Ge-W-P2 102.36(2) [101.69(9)], Ge-W-P3
91.96(2) [91.73(8)], Ge-W-P4 97.39(2) [99.30(8)].
Complex 4-W-Cl features a nearly linear coordinated germa-
À
nium atom (W-Ge-C1 177.9(3)8) and a W Ge triple-bond
length of 2.338(1) Š, which compares well with those of trans-
ꢀ
À
[X(PMe3)4W Ge-C6H3-2,6-Trip2] (X = I, W Ge 2.3206(4) Š,
À
Figure 1; X = H, W Ge 2.324(1) Š, Figure 2), but is slightly
Scheme 1. Stepwise transformation of 2-W-c into the germylidyne
complex 4-W-Cl. R=C6H3-2,6-Trip2.
version of 2-W-c into 5-W-Cl is probably initiated by an
[15]
À
insertion of 3 into the W C bond of 2-W-c. Heating of
complex 5-W-Cl in toluene at 508C gave selectively the
brown, air-sensitive germylidyne complex 4-W-Cl in an
À
unprecedented 1,2-elimination reaction, in which a Ge C
[10]
À
bond is cleaved by a W H functionality (Scheme 1). This
rearrangement reaction occurs also in the solid state when
samples of 5-W-Cl are heated slowly in vacuum to 1258C.
Alternatively, the germylidyne complex 4-W-Cl can be
directly obtained in 64% yield upon heating an equimolar
mixture of 2-W-c and 3 in toluene at 508C (Scheme 1).
Complexes 4-M-Cl (M = Mo, W) and 5-W-Cl were fully
characterized.[10] Both germylidyne complexes are thermally
stable solids which are very soluble in pentane and decom-
Figure 2. DIAMOND plot of the molecular structure of 4-W-H in the
solid state. Thermal ellipsoids are set at the 30% probability level.
Hydrogen atoms except H1 are omitted for clarity. Selected bond
lengths [Š] and bond angles [8]: W-Ge 2.324(1), W-H1 1.78(9), W-P1
2.457(3), W-P2 2.442(2), W-P3 2.429(3), W-P4 2.443(2), Ge-C1
1.977(6); W-Ge-C1 178.9(2), Ge-W-H1 179(3), Ge-W-P1 97.31(7), Ge-
W-P2 102.53(7), Ge-W-P3 97.24(7), Ge-W-P4 103.49(6).
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larger than those of the germylidyne complexes trans-[X-
ligand could be located in the difference Fourier map and lies
1
ꢀ
À
(dppe)2W Ge(h -C5Me5)] (X = Cl, Br, I, NCO, dppe =
in the equatorial plane (W H54 1.73(4) Š). This bond length
Ph2PCH2CH2PPh2, W Ge 2.293(1)–2.3060(9) Š)[17] and
lies in the range found for W H bonds by neutron diffraction
À
À
[18]
[Cp(CO)2W Ge-C6H3-2,6-Mes2] (W Ge 2.277(1) Š).
(1.715(4)–1.778(3) Š).[22] The orientation of the W H54
vector and the Ge H54 separation of 2.36(4) Š, which is
ꢀ
À
À
À
Consistent with the molecular structure shown in Figure 1,
the 31P{1H} NMR spectra of the germylidyne complexes 4-
Mo-Cl and 4-W-Cl display a singlet resonance at d = À2.7 and
À31.0 ppm (1J(W,P) = 262 Hz), respectively, and their
1H NMR spectra show the expected number and multiplicity
of signals for the m-terphenyl substituent and the PMe3
ligands of trans-configured, C2v-symmetric complexes.[10]
Compound 5-W-Cl is the first example of a tungsten
hydrido–germylidene complex to be characterized by X-ray
crystallography.[10,19] Its molecular structure shows a pentag-
onal bipyramidal, roughly Cs-symmetric complex, with two
PMe3 ligands (P2and P4) occupying the apical positions (P2-
W-P4 173.46(3)8). The other tungsten-bonded atoms (Ge, P1,
Cl, P3, and H54) lie in the equatorial plane of the bipyramid
(Figure 3).[20] Complex 5-W-Cl features a planar four-mem-
bered metallacycle (W-Ge-C37-P1 torsion angle: 0.6(2)8) that
incorporates a germanium atom in trigonal-planar coordina-
tion (sum of interligand angles: 3608). The steric pressure
exerted by the m-terphenyl substituent increases significantly
one of the external bond angles at germanium (W-Ge-C1
159.8(1)8), which in turn leads to a small endocyclic bond
angle at germanium (W-Ge-C37 97.8(1)8), thus increasing the
À
considerably larger than that expected for a Ge H single
bond (1.53–1.62Š), [23] do not indicate any bonding interac-
tion between the hydrido ligand and the unsaturated germa-
nium center.
The NMR and IR spectra corroborate the solid-state
structure of 5-W-Cl.[10] The 31P{1H} NMR spectrum displays
three resonance signals at d = À36.2(PMe
,
1J(W,PX) =
2
214 Hz), À34.4 (2” PMe 3, 1J(W,PM) = 243 Hz), and
1
À32.7 ppm (1 ” PMe3, J(W,PA) = 163 Hz) with the multipli-
city pattern of an AM2X spin system (2J(PA,PM) = 28 Hz,
2J(PA,PX) = 111 Hz, 2J(PM,PX) = 20 Hz). The hydrido signal
appears in the 1H NMR spectrum at d = 0.49 ppm as a doublet
2
of doublets of triplets (2J(P,H) = 70.8 Hz, J(P,H) = 17.6 Hz,
2J(PM,H) = 15.1 Hz, 1J(W,H) = 14.9 Hz), and the IR spectrum
À
of 5-W-Cl exhibits one n(W H) absorption band at
1812cm À1, which lies in the frequency range of W H
À
stretching modes of terminal hydrido ligands.[17c,24]
Complex 4-W-Cl is a useful starting material for the
preparation of other tungsten germylidyne complexes. Thus,
treatment of 4-W-Cl with an excess of KNCS in THF at
ambient temperature afforded the isothiocyanato complex 4-
W-NCS, which was isolated as a dark brown solid in 88%
yield (Scheme 2). Complex 4-W-NCS can also be prepared in
55% yield from 5-W-Cl and KNCS in THF at ambient
temperature. Similarly, the reaction of 4-W-Cl with an excess
of LiI in diethyl ether gave selectively the iodido derivative 4-
W-I (Scheme 2). Complex 4-W-I was isolated in 79% yield as
a red-brown, microcrystalline solid, which melts at 1948C and
starts decomposing at 1988C. Unexpectedly, treatment of 4-
W-Cl with LiNMe2 afforded selectively the hydrido–germy-
lidyne complex 4-W-H (Scheme 2). Two equivalents of
LiNMe2 were required according to NMR spectroscopy for
the quantitative consumption of 4-W-Cl, which probably
proceeds via a dimethylamido complex intermediate that
undergoes b-hydride elimination. Complex 4-W-H was iso-
lated as a crystalline, red-brown, very air-sensitive solid,
À
ring strain. The W Ge bond length of 5-W-Cl (2.4543(4) Š) is
one of the smallest to be reported so far for a tungsten–
germanium double bond,[21] and lies between those reported
À
for W Ge triple bonds (2.277(1)–2.338(1) Š, see above) and
À
W Ge single bonds (2.493(2)–2.681(3) Š).[15f,g,18] The hydrido
Figure 3. DIAMOND plot of the molecular structure of 5-W-Cl in the
solid state. Thermal ellipsoids are set at the 30% probability level.
Hydrogen atoms except H54 are omitted for clarity. Selected bond
lengths [Š] and bond angles [8]: W-Ge 2.4543(4), W-Cl 2.5217(9), W-
H54 1.73(4), W-P1 2.4806(9), W-P2 2.480(1), W-P3 2.507(1), W-P4
2.470(1), Ge-C1 2.022(3), Ge-C37 2.034(4), P1-C37 1.818(4); W-Ge-C1
159.8(1), W-Ge-C37 97.8(1), C1-Ge-C37 102.4(2), Ge-W-H54 66(1), Ge-
W-Cl 148.48(2), Ge-W-P1 67.86(2), Ge-W-P2 93.22(2), Ge-W-P3
133.46(2), Ge-W-P4 93.28(3), Cl-W-P1 80.62(3), Cl-W-P2 87.12(3), Cl-
W-P3 78.06(3), Cl-W-P4 87.73(3), P1-W-P2 91.77(3), P1-W-P4 91.36(3),
P2-W-P3 87.36(3), P2-W-P4 173.46(3), W-P1-C37 103.2(1), Ge-C37-P1
91.1(2).
Scheme 2. Chloride substitution reactions of the germylidyne complex
4-W-Cl. R=C6H3-2,6-Trip2.
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both compounds, [Os(PMe3)5] and its cyclometalation product
[Os(h2-CH2PMe2)H(PMe3)3], exist: d) H. Werner, J. Gotzig,
Organometallics 1983, 2, 547; e) S. P. Ermer, R. S. Shinomoto,
M. A. Deming, T. C. Flood, Organometallics 1989, 8, 1377.
[4] For the synthesis and reactions of [Co(PMe3)4], see: a) H.-F.
Klein, Angew. Chem. 1971, 83, 363; Angew. Chem. Int. Ed. Engl.
1971, 10, 343; b) H.-F. Klein, H. H. Karsch, Chem. Ber. 1975, 108,
944; c) H.-F. Klein, R. Hammer, Angew. Chem. 1976, 88, 61;
Angew. Chem. Int. Ed. Engl. 1976, 15, 42; d) R. Hammer, H.-F.
Klein, Z. Naturforsch. B 1977, 32, 138.
[5] Selected references for the complexes [M(PMe3)4] (M = Ni, Pd,
Pt): a) C. A. Tolman, J. Am. Chem. Soc. 1970, 92, 2956; b) H.-F.
Klein, H. Schmidbaur, Angew. Chem. 1970, 82, 885; Angew.
Chem. Int. Ed. Engl. 1970, 9, 903; c) D. H. Gerlach, A. R. Kane,
G. W. Parshall, J. P. Jesson, E. L. Muetterties, J. Am. Chem. Soc.
1971, 93, 3543; d) W. Kuran, A. Musco, Inorg. Chim. Acta 1975,
12, 187; e) H.-F. Klein, H. H. Karsch, Chem. Ber. 1976, 109, 2515;
f) B. E. Mann, A. Musco, J. Chem. Soc. Dalton Trans. 1980, 776;
g) H. Werner, W. Bertleff, Chem. Ber. 1983, 116, 823; h) R. Benn,
H. M. Büch, R.-D. Reinhardt, Magn. Reson. Chem. 1985, 23,
559; i) D. Milstein, J. Chem. Soc. Chem. Commun. 1986, 817;
j) A. G. Avent, F. G. N. Cloke, J. P. Day, E. A. Seddon, K. R.
Seddon, S. M. Smedley, J. Organomet. Chem. 1988, 341, 535;
k) H.-F. Klein, B. Zettel, U. Flörke, H.-J. Haupt, Chem. Ber.
1992, 125, 9; l) W. Lin, S. R. Wilson, G. S. Girolami, Inorg. Chem.
1997, 36, 2662; m) H. Yamashita, M. Tanaka, M. Goto, Organo-
metallics 1997, 16, 4696.
which decomposes upon melting at 1898C. Complexes 4-W-X
(X = NCS, I, H) were fully characterized.[10] The molecular
structures of 4-W-I and 4-W-H (Figures 1 and 2, respectively)
reveal the same bonding features of the germylidyne ligand as
4-W-Cl, including the almost-linear coordination geometry at
germanium (W-Ge-Caryl: 175.79(7)8 (4-W-I), 178.9(2)8 (4-W-
À
H)) and the very short W Ge bonds (2.3206(4) Š (4-W-I),
2.324(1) Š (4-W-H)).[25] The solid-state Raman spectrum of 4-
W-H displays a n(W H) band at 1658 cm
at higher energy than that of trans-[H(dmpe)2W CMes]
,
À1 [26] which appears
À
ꢀ
(n(W H) 1600 cmÀ1; dmpe = Me2PCH2CH2PMe2).[27] This
À
observation suggests that the germylidyne ligand exerts a
weaker trans influence than the carbyne ligand.[17c] In the
1H NMR spectrum of 4-W-H the hydrido ligand gives rise to a
quintet signal at d = À5.56 ppm (2J(P,H) = 30.6 Hz, 1J(W,H) =
61.2Hz). The 31P{1H} NMR spectra of the germylidyne
complexes display one singlet resonance for the PMe3 ligands
at d = À28.2 (4-W-NCS), À46.8 (4-W-I), and À30.6 ppm (4-W-
H), thus confirming the trans configuration of the complexes.
The 31P NMR signal is in all cases flanked by a pair of
1
tungsten satellites, and the J(W,P) coupling constants have
similar values (4-W-NCS 257 Hz, 4-W-I 256 Hz, 4-W-H
252 Hz) compared to that of 4-W-Cl (262 Hz). Finally, the
13C{1H} NMR spectra of all germylidyne complexes exhibit a
characteristic low-field signal for the germanium-bonded
[6] The term electron-rich metal center is used here to indicate the
presence of filled metal-centered molecular orbitals at high
energy in these complexes.
C
aryl atom at d = 177.1 (4-W-Cl), 176.6 (4-W-NCS), 174.4 (4-
W-I), and 178.1 ppm (4-W-H), which appears at slightly lower
field than that of 3 (d = 164.6 ppm).
[7] a) V. C. Gibson, C. E. Graimann, P. M. Hare, M. L. H. Green,
J. A. Bandy, P. D. Grebenik, K. Prout, J. Chem. Soc. Dalton
Trans. 1985, 2025; b) M. L. H. Green, G. Parkin, M. Chen, K.
Prout, J. Chem. Soc. Dalton Trans. 1986, 2227; c) D. Rabinovich,
R. Zelman, G. Parkin, J. Am. Chem. Soc. 1990, 112, 9632; d) T.
Hascall, V. J. Murphy, G. Parkin, Organometallics 1996, 15, 3910;
e) K. E. Janak, J. M. Tanski, D. G. Churchill, G. Parkin, J. Am.
Chem. Soc. 2002, 124, 4182; f) G. Zhu, J. M. Tanski, D. G.
Churchill, K. E. Janak, G. Parkin, J. Am. Chem. Soc. 2002, 124,
13658; g) T. Hascall, M.-H. Baik, B. M. Bridgewater, J. H. Shin,
D. G. Churchill, R. A. Friesner, G. Parkin, Chem. Commun.
2002, 2644; h) G. Zhu, G. Parkin, Inorg. Chem. 2005, 44, 9637.
[8] E. Carmona, J. M. Marin, M. L. Poveda, J. L. Atwood, R. D.
Rogers, Polyhedron 1983, 2, 185.
[9] P. R. Sharp, J. C. Bryan, J. M. Mayer, Inorg. Synth. 1990, 28, 326.
[10] The Supporting Information contains detailed experimental
procedures for the preparation and the analytical and spectro-
scopic characterization of the starting materials 2-Mo and 2-W-c
and of all products. It also contains the NMR spectroscopic data
of 3. CCDC-608272 (4-W-Cl·n-C5H12), CCDC-608273 (4-W-
I·0.5n-C5H12), CCDC-608274 (4-W-H), and CCDC-608275 (5-
W-Cl·n-C5H12) contain the supplementary crystallographic data
for this paper. These data can be obtained free of charge from
The Cambridge Crystallographic Data Centre via www.ccdc.
cam.ac.uk/data_request/cif.
[11] The advantages of the new method are the following: a) the use
of PMe3 as solvent is avoided, and b) the starting materials 1-Mo
and 1-W can be readily obtained in good overall yields starting
from MoCl5 and WCl6, respectively.
[12] Depending on the work-up conditions, either pure 2-Mo or a
mixture of 2-Mo and its cyclometalation product [Mo(h2-
CH2PMe2)H(PMe3)4] (2-Mo-c) was isolated (see the Supporting
Information).
[13] a) L. Pu, M. M. Olmstead, P. P. Power, B. Schiemenz, Organo-
metallics 1998, 17, 5602.
[14] The outcome of the reaction with 3 is the same when starting
either from pure 2-Mo or a mixture of 2-Mo and its cyclo-
This work demonstrates that reactions of organogerma-
nium(II) chlorides with electron-rich metal complexes can
follow unprecedented pathways, finally leading to compounds
with metal–germanium triple bonds. This work complements
our recent studies on the activation of organotetrel(II) halides
by d6 metal centers, which have culminated in the isolation of
compounds featuring triple bonds to linear-coordinated
germanium, tin, and lead centers.[17,28] Extension of the
methodology presented here to Group 8 metals is quite
appealing, and should lead to ylidyne complexes of metals
with a different d-electron configuration and coordination
sphere. Efforts in this direction are in progress.
Received: May 23, 2006
Published online: August 22, 2006
Keywords: germanium · hydride ligands · molybdenum ·
.
multiple bonds · tungsten
[1] a) F. G. N. Cloke, K. P. Cox, M. L. H. Green, J. Bashkin, K.
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[2] D. Rabinovich, R. Zelman, G. Parkin, J. Am. Chem. Soc. 1992,
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[3] For M = Fe, Ru, only the cyclometalation products [M(h2-
CH2PMe2)H(PMe3)3] are known: a) J. W. Rathke, E. L. Muet-
terties, J. Am. Chem. Soc. 1975, 97, 3272; b) H. H. Karsch, H.-F.
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5990 www.angewandte.org
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Angewandte
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metalation product [Mo(h2-CH2PMe2)H(PMe3)4] (2-Mo-c); see
the Supporting Information).
C. J. Unkefer, C. J. Burns, G. J. Kubas, A. Lledꢀs, F. Maseras, J.
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[15] Insertions of germanium(II) halides in metal–carbon bonds are
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145, 245; b) J. SatgØ, Chem. Heterocycl. Comp. 2000, 35, 1013.
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metal – heteroatom, metal – metal, or metal – hydrogen bonds:
c) P. Rivi›re, J. SatgØ, A. Boy, J. Organomet. Chem. 1975, 96, 2 5;
d) A. Castel, P. Rivi›re, J. SatgØ, J. J. E. Moreau, R. J. P. Corriu,
Organometallics 1983, 2, 1498; e) A. C. Filippou, J. G. Winter, G.
Kociok-Köhn, I. Hinz, J. Organomet. Chem. 1997, 544, 2 2 5;
f) A. C. Filippou, J. G. Winter, G. Kociok-Köhn, C. Troll, I. Hinz,
Organometallics 1999, 18, 2649, and references therein; g) A. C.
Filippou, P. Portius, J. G. Winter, G. Kociok-Köhn, J. Organomet.
Chem. 2001, 628, 11.
[16] The m-terphenyl substituent adopts in all germylidyne com-
plexes an eclipsed conformation with respect to the {WX-
(PMe3)4} fragment (X = Cl, I, H), as evidenced by the interplane
angle (4-W-Cl 1.8(3)8, 4-W-I 3.60(7)8, 4-W-H 7.9(2)8) between
the least-square plane through the tungsten atom, germanium
atom, and the central aryl ring carbon atoms, and the least-
square plane of the atoms Ge, W, P1, and P3. It should be also
noted that all germylidyne complexes show a similar geometric
deviation of the WP4 core from planarity. The two trans-located
PMe3 ligands which are oriented perpendicular to the germa-
nium-bonded phenyl ring (P2and P4 in Figure 1 and Figure 3)
are bent more strongly away from the germylidyne ligand than
the other two PMe3 ligands (P1 and P3).
À
[25] It is noticeable that the W Ge triple-bond length of 4-W-H does
not differ from those of 4-W-X (X = Cl, I), despite the presence
of a hydrido ligand which exerts a strong trans influence. This
À
finding suggests that the s-bonding part of the W Ge bond,
which is expected to be weakened in 4-W-H by the hydrido
À
ligand, has a minor influence on the W Ge triple-bond length.
À
[26] The W H stretching mode of 4-W-H was also observed in the IR
spectrum at 1654 cmÀ1 (Supporting Information).
[27] F. Furno, T. Fox, H. W. Schmalle, H. Berke, Organometallics
2000, 19, 3620.
[28] a) A. C. Filippou, P. Portius, A. I. Philippopoulos, H. Rohde,
Angew. Chem. 2003, 115, 461; Angew. Chem. Int. Ed. 2003, 42,
445; b) A. C. Filippou, A. I. Philippopoulos, G. Schnakenburg,
Organometallics 2003, 22, 3339; c) A. C. Filippou, H. Rohde, G.
Schnakenburg, Angew. Chem. 2004, 116, 2293; Angew. Chem.
Int. Ed. 2004, 43, 2243; d) A. C. Filippou, N. Weidemann, G.
Schnakenburg, H. Rohde, A. I. Philippopoulos, Angew. Chem.
2004, 116, 6674; Angew. Chem. Int. Ed. 2004, 43, 6512; e) A. C.
Filippou, G. Schnakenburg, A. I. Philippopoulos, N. Weidemann,
Angew. Chem. 2005, 117, 6133; Angew. Chem. Int. Ed. 2005, 44,
5979.
[17] a) A. C. Filippou, A. I. Philippopoulos, P. Portius, D. U. Neu-
mann, Angew. Chem. 2000, 112, 2881; Angew. Chem. Int. Ed.
2000, 39, 2778; b) A. C. Filippou, P. Portius, A. I. Philippopoulos,
Organometallics 2002, 21, 653; c) A. C. Filippou, A. I. Philip-
popoulos, P. Portius, G. Schnakenburg, Organometallics 2004, 23,
4503.
[18] L. Pu, B. Twamley, S. T. Haubrich, M. M. Olmstead, B. V. Mork,
R. S. Simons, P. P. Power, J. Am. Chem. Soc. 2000, 122, 650.
[19] Only
one
hydrido–germylidene
=
complex,
[{PhB-
(CH2PPh2)3}(H)2Ir GeMes2], has been reported so far: J. D.
Feldman, J. C. Peters, T. Don Tilley, Organometallics 2002, 21,
4065.
[20] The maximum deviation of the atoms W, Ge, P1, Cl, P3, and H54
from the least-square plane is less than 10 pm.
À
[21] The W Ge bond length of 5-W-Cl compares well with that of the
5
=
germylidene complex [(h -C5Me4Et)W(CO)2( GeMe2)GeMe3]
À
(W Ge 2.459(2) Š: K. Ueno, K. Yamaguchi, H. Ogino, Organo-
metallics 1999, 18, 4468), but is smaller than those of other
À
tungsten germylidene complexes (W Ge 2.505(2) – 2.632(2) Š):
a) G. Huttner, U. Weber, B. Sigwarth, O. Scheidsteger, H. Lang,
L. Zsolnai, J. Organomet. Chem. 1985, 282, 331; b) P. Jutzi, B.
Hampel, K. Stroppel, C. Krüger, K. Angermund, P. Hofmann,
Chem. Ber. 1985, 118, 2789; c) P. Jutzi, B. Hampel, M. B.
Hursthouse, A. J. Howes, J. Organomet. Chem. 1986, 299, 19;
d) W.-W. du Mont, L. Lange, S. Pohl, W. Saak, Organometallics
1990, 9, 1395; e) N. Tokitoh, K. Manmaru, R. Okazaki, Organo-
metallics 1994, 13, 167.
[22] R. Bau, M. H. Drabnis, Inorg. Chim. Acta 1997, 259, 2 7.
À
[23] The experimental value for the Ge H bond length of GeH4 is
1.5251(5) Š: J. H. Callomon, E. Hirota, K. Kuchitsu, W. J.
Lafferty, A. G. Maki, C. S. Pote, Structure Data of Free Poly-
atomic Molecules, Landolt-Börnstein, New Series II, Vol. 7 (Eds.
K.-H. Hellwege, A. M. Hellwege), Springer, Berlin, 1976. The
À
calculated value for the Ge H bond length of GeH2 ranges from
1.584 to 1.617 Š: Q.-S. Li, R.-H. Lü, Y. Xie, H. F. Schaefer III, J.
Comput. Chem. 2002, 23, 1642.
[24] M-H-E three-center interactions (M = Mo, E = Ge; M = W, E =
Si) give rise to n(M-H-E) absorption bands at considerably lower
wave numbers: a) J. L. Vincent, S. Luo, B. L. Scott, R. Butcher,
Angew. Chem. Int. Ed. 2006, 45, 5987 –5991
ꢀ 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.angewandte.org
5991