Halogermanium(II) complexes having phenylamidinate as supporting ligands: Syntheses, characterizations, and reactivities

Article abstract of DOI:10.1021/om100347c

Novel germylenes [{Me₃SiNC(Ph)NSiMe₃}GeX] (X = Cl, Br, I) and [{Me₃SiNC(Ph)NSiMe₃}₂Ge] with the bidentate phenylamidinato ligand have been synthesized in high yields by a salt metathesis reaction betw

Full text of DOI:10.1021/om100347c

Organometallics 2010, 29, 3039–3046 3039
DOI: 10.1021/om100347c
Halogermanium(II) Complexes Having Phenylamidinate As Supporting
Ligands: Syntheses, Characterizations, and Reactivities
Dimitri Matioszek,† Nadia Katir,† Nathalie Saffon,‡ and Annie Castel*,†
†
ꢀ ꢀ
ꢀ
ꢀ
Laboratoire Heterochimie Fondamentale et Appliquee, UMR/CNRS 5069, Universite Paul Sabatier,
‡
118 Route de Narbonne, 31062 Toulouse Cedex 09, France, and Structure Federative Toulousaine en Chimie
ꢀ ꢀ
Moleꢀculaire (FR2599), UniversiteꢀPaul Sabatier, 118 Route de Narbonne, 31062 Toulouse Cedex 09, France
Received April 26, 2010
Novel germylenes [{Me3SiNC(Ph)NSiMe3}GeX] (X = Cl, Br, I) and [{Me3SiNC(Ph)NSiMe3}2Ge]
with the bidentate phenylamidinato ligand have been synthesized in high yields by a salt metathesis
reaction between Cl2Ge dioxane or I2Ge and the lithium salt of the ligand. They were characterized by
3
1H and 13C NMR and mass spectrometry and single-crystal X-ray structure analyses, which confirmed
N-chelation and a three-coordinate germanium center. The cycloaddition reactions with o-quinone led
to cycloadducts, whose structures were determinedby X-ray analyses. The chelation of the ligand to the
metal center was conserved, affording penta- and hexacoordinated germanium(IV) atoms. Complexation
reactions with [codW(CO)4] and [nbdMo(CO)4] resulted in trinuclear bis(germanium(II)) transition-
metal complexes in “trans” octahedral geometry.
Introduction
stannylenes with chelating anilido-imine ligands showing
both the chelating and electron donor properties of these
ligands.7 Although a large number of germanium(II) com-
pounds have been isolated, the search for new ligands able to
stabilize low-coordinate compounds is still very important
today. Indeed, an unexpected application of dicyclopenta-
dienyl, amido, and alkoxy germylenes as precursors of
nanomaterials has recently been described and opens a wide
field of investigation.8 Likewise, amidinate ligands have been
emphasized as convenient precursors for CVD methods.9
They are bidentate, three-atom-bridging moieties with the
general formula [R0NC(R)NR0]-. Another characteristic is
the possibility of modifying their steric and electronic pro-
perties by changing the organic substituents at the nitrogen
atom as well at the bridging carbon atom. Only a few chloro-
germylenes with amidinate or guanidinate ligands10 and with
alkyl or aryl substituents at nitrogen atoms5d,e,11 have been
reported so far. With the bulky trimethylsilyl group as sub-
stituent, only the mixed amidinato amido complex [{Me3-
SiNC(t-Bu)NSiMe3}Ge{N(SiMe3)2}] was obtained because
of a rearrangement of the lithium amidinate salt.12 1,3
During the last three decades, the stabilization and isola-
tion of compounds with group 14 elements in unusual or low
oxidation states has received considerable attention, parti-
cularly since the discovery of the Arduengo-type carbene in
1991.1 The rapid development of the chemistry of N-hetero-
cyclic carbenes (NHC) and their use in transition-metal
catalysis2 and more recently as organocatalysts3 have in-
creased interest in their higher congeners, NHGe or NHSn,
although they had been discovered earlier.4 Since these initial
reports, the chemistry of stable NHGe has largely been
developed.5 Besides the divalent NHGe featuring two nor-
mal covalent Ge-N bonds, the tricoordinated species having
amino/imino ligands with a covalent Ge-N bond and a
coordinative GefN bond have also been reported. Exam-
ples of such ligands include amidinates,5b aminotroponi-
minates,6 and β-diketiminates.5d In this context, we have
recently reported the preparation of new germylenes and
*To whom correspondence should be addressed. E-mail: castel@
chimie.ups-tlse.fr.
(1) Arduengo, A. J., III; Harlow, R. L.; Kline, M. J. Am. Chem. Soc.
1991, 113, 361.
(2) Glorius, F. N-Heterocyclic Carbenes in Transition Metal Catalysis,
1st ed.; Springer: Berlin, 2006.
(3) Marion, N.; Diez-Gonzalez, S.; Nolan, S. P. Angew. Chem., Int.
(8) (a) Mathur, S.; Shen, H.; Sivakov, V.; Werner, U. Chem. Mater.
2004, 16, 2449. (b) Gerung, H.; Bunge, S. D.; Boyle, T. J.; Brinker, C. J.; Han,
S. M. Chem. Commun. 2005, 1914. (c) Gerung, H.; Boyle, T. J.; Tribby, L. J.;
Bunge, S. D.; Brinker, C. J.; Han, S. M. J. Am. Chem. Soc. 2006, 128, 5244.
(d) Boyle, T. J.; Tribby, L. J.; Ottey, L. A. M.; Han, S. M. Eur. J. Inorg.
Chem. 2009, 5550. (e) Lee, D. C.; Pietryga, J. M.; Robel, I.; Werder, D. J.;
Schaller, R. D.; Klimov, V. I. J. Am. Chem. Soc. 2009, 131, 3436.
(9) Riedel, R.; Greiner, A.; Miehe, G.; Dressler, W.; Fuess, H.; Bill, J.;
Aldinger, F. Angew. Chem., Int. Ed. Engl. 1997, 36, 603.
Ed. 2007, 46, 2988.
(4) (a) Veith, M.; Grosser, M. Z. Naturforsch. 1982, 37b, 1375.
(b) Herrmann, W. A.; Denk, M.; Behm, J.; Scherer, W.; Klingan, F.-R.; Bock,
H.; Solouki, B.; Wagner, M. Angew. Chem., Int. Ed. 1992, 31, 1485.
(5) (a) Lappert, M. F. Main Group Met. Chem. 1994, 17, 183. (b) K€ulh, O.
Coord. Chem. Rev. 2004, 248, 411. (c) Leung, W.-P.; Kan, K.-W.; Chong,
K.-H. Coord. Chem. Rev. 2007, 251, 2253. (d) Nagendran, S.; Roesky, H. W.
Organometallics 2008, 27, 457. (e) Mizuhata, Y.; Sasamori, T.; Tokitoh, N.
Chem. Rev. 2009, 109, 3479.
(10) Jones, C.; Rose, R. P.; Stasch, A. Dalton Trans. 2008, 2871.
(11) (a) Nagendran, S.; Sen, S. S.; Roesky, H. W.; Koley, D.;
€
Grubmuller, H.; Pal, A.; Herbst-Irmer, R. Organometallics 2008, 27,
5459. (b) Green, S. P.; Jones, C.; Junk, P. C.; Lippert, K.-A.; Stasch, A. Chem.
Commun. 2006, 3978.
(12) Foley, S. R.; Zhou, Y.; Yap, G. P. A.; Richeson, D. S. Inorg.
(6) Dias, H. V. R.; Wang, Z.; Jin, W. Coord. Chem. Rev. 1998, 176, 67.
(7) Mcheik, A.; Katir, N.; Castel, A.; Gornitzka, H.; Massou, S.;
ꢁ
Riviere, P.; Hamieh, T. Eur. J. Inorg. Chem. 2008, 5397.
Chem. 2000, 39, 924.
r
2010 American Chemical Society
Published on Web 06/10/2010
pubs.acs.org/Organometallics

3040 Organometallics, Vol. 29, No. 13, 2010
Matioszek et al.
Scheme 1
Trimethylsilyl shifts within the amidinate framework were
suggested to lose t-BuCN and generate (Me3Si)2NLi, which
in turn reacted with the transient chlorogermylene. Chang-
ing a tert-butyl to a methyl group partially stabilizes the
lithium salt. With a phenyl group at the methine carbon,
while the unstable amidonato chlorosilylene decomposed
into a six-coordinate [{Me3SiNC(Ph)NSiMe3}2SiCl2],13 the
corresponding tin analogue was obtained by treatment in
situ with lithium hexamethyldisilazide.14 However to the best
of our knowledge, this ligand remains unknown in germa-
nium chemistry. Thus, our study in this area will explore the
use of a phenylamidinato ligand to stabilize halogerma-
nium(II) species and investigate its effect on their reactivity.
The present work reports the preparation of novel pheny-
lamidinate-based germanium(II) complexes and their full
characterization including single-crystal X-ray diffraction
structure determinations. In order to gain insights into the
chemical behavior of these species, oxidative cycloadditions
with o-quinone and complexation with transition-metal
complexes will be described.
Figure 1. Molecular structures of 2a (X = Cl) and 2c (X = Br).
Thermal ellipsoids are set at 50% probability. Hydrogen atoms
and disordered atoms have been omitted for clarity. Selected
˚
bond distances [A] and bond angles [deg] for 2a: Ge(1)-
Cl(1) 2.2632(18); Ge(1)-N(1) 2.031(4); Ge(1)-N(2) 2.059(4);
C(1)-N(1) 1.337(6); C(1)-N(2) 1.326(6); N(1)-Ge(1)-N(2)
65.56(16); N(1)-Ge(1)-Cl(1) 95.69(13); N(2)-Ge(1)-Cl(1)
˚
97.27(15). Selected bond distances [A] and bond angles [deg]
for 2c: Ge(1)-Br(1) 2.4239(12); Ge(1)-N(1) 2.049(6); Ge(1)-
N(2) 2.037(5); C(1)-N(1) 1.316(8); C(1)-N(2) 1.351(8); N(1)-
Ge(1)-N(2) 66.0(2);N(1)-Ge(1)-Br(1) 97.55(17);N(2)-Ge(1)-
Br(1) 95.81(16).
SnCl] exclusively. In our case, the combination of trimethyl-
silyl and phenyl substituents on the amidinato moieties
allowed stabilization of both the amidinate salt 1 and halo-
germylenes without preventing access to 3.
Addition of an excess of Me3SiBr to 2a at room tempera-
ture led to bromogermylene 2c quantitatively.
Results and Discussion
These germanium(II) species were isolated as pale yellow
powders which are stable under inert atmosphere and can be
stored for long periods at low temperature (-30 °C). They
show high solubility in organic solvents such as pentane,
hexanes, diethyl ether, THF and toluene. Their stability in
solution decreases rapidly from 2a, 2c, 3 to 2b. All attempts
to crystallize 2b failed, and only the salt [{H(Me3Si)NC-
(Ph)N(SiMe3)H}þ I-]17 was isolated and its structure eluci-
dated by X-ray diffraction method. All the compounds were
perfectly characterized by 1H and 13C NMR, and mass
spectrometry. In all cases, only a single methyl group signal
Ge(II) Complexes of the [(Me3SiNC(Ph)NSiMe3)]- Anion.
The lithium amidinate salt 1 was prepared by treatment of
benzonitrile with (Me3Si)2NLi in diethyl ether according to
the method previously described.15 Stoichiometric reactions
of 1 with Cl2Ge dioxane and with I2Ge led to the formation
3
of new halogermylenes 2a and 2b in almost quantitative
yields, 95% and 98%, respectively. No trace of the amidinato
amido complex was detected in the crude reaction product,
confirming the stability of 1. In addition, the reaction is
highly selective without forming bis(amidinate)germylene 3
which could be easily prepared using two equivalents of 1
(Scheme 1). Note that it is the first example of such selectivity
in the group 14 series. Recently, Gibson et al. reported that
the nature of the group on methine carbon highly regu-
lates such reactions.16 By using the methyl group, a mixture
of chloromonoamidinate [{ArNC(Me)NAr}SnCl] and bis-
(amidinate) tin(II) complexes [{ArNC(Me)NAr}2Sn] (Ar =
2,6-i-Pr2C6H3) was obtained, whereas the bulkier tert-butyl
ligand gave the monochloride complex [{ArNC(t-Bu)NAr}-
1
was observed in the NMR spectra. When a dynamic H
NMR experiment was performed in the temperature range
þ20 °C to -80 °C for 3, a singlet was always observed
indicating fluxional behavior with equivalent nitrogen atoms
and the existence of a symmetrical coordination at the
germanium center on the NMR time-scale.
To establish the geometries of these germanium(II) com-
pounds, X-ray crystal structure determinations were done.
The halogermylenes 2a and 2c are isomorphous and their
structures are very similar to those recently described for
chloroamidinato11a and guanidinato germylenes.10 Struc-
tures of 2a and 2c are given in Figure 1 together with selected
bond lengths and angles. The amidinato ligand chelates to
the germanium center to form a four membered ring with the
(13) So, C.-W.; Roesky, H. W.; Gurubasavaraj, P. M.; Oswald, R. B.;
Gamer, M. T.; Jones, P. G.; Blaurock, S. J. Am. Chem. Soc. 2007, 129,
12049.
(14) Aubrecht, K. B.; Hillmyer, M. A.; Tolman, W. B. Macromole-
cules 2002, 35, 644.
(15) Edelmann, F. T. Coord. Chem. Rev. 1994, 137, 403.
(16) Nimitsiriwat, N.; Gibson, V. C.; Marshall, E. L.; White, A. J. P.;
Dale, S. H.; Elsegood, M. R. J. Dalton Trans. 2007, 4464.
(17) Molecular structure of [{H(Me3Si)NC(Ph)N(SiMe3)H}þI-] are
given in the Supporting Information.

Article
Organometallics, Vol. 29, No. 13, 2010 3041
Figure 2. ORTEP view of compound 3 (50% probability level for the thermal ellipsoids). Hydrogen atoms have been omitted for
˚
clarity. Selected bond distances [A] and bond angles [deg]: Ge(1)-N(1) 2.0106(18); Ge(1)-N(2) 2.1948(19); Ge(1) N(3) 2.3397(18);
3 3 3
Ge(1)-N(4) 2.0121(18); C(1)-N(1) 1.346(3); C(1)-N(2) 1.322(3); C(14)-N(3) 1.308(3); C(14)-N(4) 1.348(3); N(1)-Ge(1)-N(2)
64.21(7); N(1)-Ge(1)-N(3) 100.68(7); N(1)-Ge(1)-N(4) 98.22(8); N(2)-Ge(1)-N(3) 155.07(7); N(2)-Ge(1)-N(4) 99.04(7);
N(3)-Ge(1)-N(4) 62.01(7).
Scheme 2
˚
˚
˚
germanium atom lying 0.38 A (2a) and 0.39 A (2c) out of the
plane defined by the other three atoms. The three-coordinate
germanium atom adopts a significantly distorted pyramidal
geometry (the sums of the bond angles are 258° and 259° for
2a and 2c, respectively) with the Ge-halogen bond approxi-
mately orthogonal to the cycle. The Ge-Cl distance (2.2632(18)
shorter than the Ge-N(3) (2.3397(18) A). The latter value is
˚
between that of the axial Ge-N bond (2.300(2) A) found in
[{i-PrNC(Me)Ni-Pr}2Ge],19 which displays a four-coordi-
nate germanium center and that of the Ge-N interaction
(2.474 A) in the complex [{CyNC(Me)NCy}2Ge]20,21 having
˚
three-coordinate germanium. In our case, the slight short-
ening of the neighboring N-C bond, C(14) -N(3) (1.308(3)
A), the lack of symmetry of the molecule and a sum of angles
at germanium atom (261°) which approximates the ideal
trigonal pyramid geometry (270°), are consistent with a
three-coordinate germanium center with one bidentate and
one monodentate amidinate ligand. Accordingly, the Me3Si
groups are different in the solid-state structure, but in solu-
tion a rapid exchange between the two amidinato moieties
˚
A) is very close to that observed by Roesky et al. in [{t-
˚
˚
BuNC(Ph)Nt-Bu}GeCl] (2.2572(13) A)] which also has a
phenyl group in the bridging carbon.11a The Ge-Br bond
˚
length (2.4239(12) A) lies in the range of standard Ge-Br
bonds.18 Regarding the bis(amidinate)germylene 3 (Figure 2),
we observed two amidinato systems, one presenting a chela-
ted ring with the Ge-N distances (2.0106(18) and 2.1948(19)
A) in the range of those observed previously10 and the second
˚
with a more distorted structure having two different Ge-N
˚
distances, the Ge-N(4) (2.0121(18) A) being significantly
€
(19) Karsch, H. H.; Schluter, P. A.; Reisky, M. Eur. J. Inorg. Chem.
1998, 433.
(20) Foley, S. R.; Bensimon, C.; Richeson, D. S. J. Am. Chem. Soc.
€
(18) (a) Driess, M.; Yao, S.; Brym, M.; van Wullen, C. Angew. Chem.,
Int. Ed. 2006, 45, 4349. (b) Rupar, P. A.; Jennings, M. C.; Baines, K. M.
Organometallics 2008, 27, 5043.
1997, 119, 10359.
(21) This value was extrated from the CIF file.

3042 Organometallics, Vol. 29, No. 13, 2010
Matioszek et al.
Figure 3. ORTEP view of compound 4a (50% probability level
for the thermal ellipsoids). Hydrogen atoms have been omitted
˚
for clarity. Selected bond distances [A] and bond angles [deg]:
Ge(1)-Cl(1) 2.1556(8); Ge(1)-N(1) 1.978 (3); Ge(1)-N(2)
1.969(3); C(1)-N(1) 1.342(4); C(1)-N(2) 1.319(4); Ge(1)-O(1)
1.8326(19); Ge(1)-O(2) 1.823(2); N(1)-Ge(1)-N(2) 68.04(10);
N(1)-Ge(1)-Cl(1) 105.44(8); N(2)-Ge(1)-Cl(1) 101.69(8);
O(1)-Ge(1)-Cl(1) 103.17(7); O(2)-Ge(1)-Cl(1) 108.50(7);
O(1)-Ge(1)-N(1) 97.05(10); O(1)-Ge(1)-N(2) 153.74(10);
O(2)-Ge(1)-N(1) 143.15(10); O(2)-Ge(1)-N(2) 91.18(10);
O(1)-Ge(1)-O(2) 88.92(9).
Figure 4. ORTEP view of compound 5 (50% probability level
for the thermal ellipsoids). Hydrogen atoms and disordered
˚
atoms have been omitted for clarity. Selected bond distances [A]
could explain the equivalence of these substituents in the 1H
and 13C NMR spectra as previously mentioned.
Reactivity. These structural results imply that the geome-
try of the germanium atom is in good agreement with a
nonhybridized system with bonds formed by using nearly
pure p orbitals while the lone-pair must occupy an orbital
with high s character. To verify whether these germanium
complexes retain their specific character of a divalent species,
an oxidative cycloaddition reaction with 3,5-di-tert-butyl-
ortho-quinone was examined.22
and bond angles [deg]: Ge(1)-N(1) 2.023(4); Ge(1)-N(2)
2.025(4); Ge(1)-N(3) 2.004(4); Ge(1)-N(4) 2.065(3); C(1)-
N(1) 1.332(5); C(1)-N(2) 1.342(5); C(14)-N(3) 1.332(5); C-
(14)-N(4) 1.338(5); Ge(1)-O(1) 1.860(3); Ge(1)-O(2) 1.868(3);
N(1)-Ge(1)-N(2) 66.85(13); N(1)-Ge(1)-N(3) 162.67(14);
N(1)-Ge(1)-N(4) 99.37(14); N(2)-Ge(1)-N(3) 102.46(14);
N(2)-Ge(1)-N(4) 94.57(14); N(3)-Ge(1)-N(4) 66.96(14);
O(1)-Ge(1)-N(1) 93.73(14); O(1)-Ge(1)-N(2) 88.10(13);
O(1)-Ge(1)-N(3) 99.67(14); O(1)-Ge(1)-N(4) 166.63(13);
O(2)-Ge(1)-N(1) 96.73(14); O(2)-Ge(1)-N(2) 162.91(14);
O(2)-Ge(1)-N(3) 94.62(12); O(2)-Ge(1)-N(4) 92.77(12);
O(1)-Ge(1)-O(2) 88.31(12).
Oxidative Cycloaddition. Treatment of 2a-c and 3 with
ortho-quinone at room temperature in toluene (or diethyl
ether for 3) led to a progressive disappearance of the green
color of ortho-quinone. After evaporation of the solvents, the
cycloadducts 4a-c and 5 were isolated as powders which
could be crystallized from toluene (or diethylether for 5) at
-24 °C (Scheme 2).
was recently reported for a monosilaepoxide stabilized by
amidinato ligand.23 As expected, the Ge-N bond distances
(1.969(3) and 1.978(3) A) are shortened compared to those
1
˚
While the H NMR spectra of 4a-c revealed the equiva-
of the germanium(II) starting compound because of the loss
of their conjugated character.7,20 The X-ray analysis of 5
reveals a six coordinate germanium center that has dis-
torted octahedral coordination geometry with the four
nitrogen atoms of the amidinato ligands and with the two
oxygen atoms of the quinonic cycle. By contrast with the
corresponding germylene 3, the two amidinate ligands
exhibit only a very slight difference in the Ge-N bond
lence of the two Me3Si groups, the four Me3Si groups in 5 are
nonequivalent and four signals were observed at -0.10, 0.00,
0.14, and 0.19 ppmprobably because of the steric hindrance of
the molecule. 13C and 29Si NMR spectra showed the same
nonequivalence of trimethylsilyl groups. A complete assign-
ment of these signals was obtained by 2D homonuclear
(COSY) andheteronuclearexperiments (HSQCand HMBC).
Molecular structures of 4a and 5 were determined by
single-crystal X-ray analysis and are shown in Figures 3
and 4, respectively with selected bond lengths and angles.
In 4a, the chelating character of the ligand to the metal
center, as was observed for the corresponding germylene, is
conserved. The germanium atom is penta-coordinate and
the geometry around this atom is in between a distorted
trigonal bipyramidal geometry with one nitrogen atom of
the amidinato group N(2) and one oxygen atom O(1) of the
quinonic cycle in axial positions as we previously observed
with anilido-imine ligands7 and a distorted square pyramid
with the chlorine atome on the top. A comparable structure
˚
lengths (in the range from 2.004 to 2.065 A) and are
almost perfectly chelated to the germanium atom in spite
of the increased steric hindrance compared to the germ-
anium(II) compound 3. As a consequence of this steric
˚
congestion, the Ge-O distances (1.860(3) and 1.868(3) A)
are longer than those of the chloromonoamidinate
˚
germanium(IV) 4a (1.8326(19) and 1.823(2) A) but still lie
in the range of covalent Ge-O bonds.7,24 1H and 13C NMR
(23) Ghadwal, R. S.; Sen, S. S.; Roesky, H. W.; Granitzka, M.;
Kratzert, D.; Merkel, S.; Stalke, D. Angew. Chem., Int. Ed. 2010, 49,
3952.
(24) Zemlyansky, N. N.; Borisova, I. V.; Khrustalev, V. N.; Antipin,
M. Yu.; Ustynyuk, Y. A.; Nechaev, M. S.; Lunin, V. V. Organometallics
2003, 22, 5441.
ꢁ
ꢀ
(22) Riviere, P.; Castel, A.; Satge, J.; Guyot, D. J. Organomet. Chem.
1986, 315, 157.

Article
Organometallics, Vol. 29, No. 13, 2010 3043
Figure 5. Molecular structures of 6 (M = W) and 7 (M = Mo). Thermal ellipsoids are set at 50% probability. Hydrogen atoms have
˚
been omitted for clarity. Selected bond distances [A] and bond angles [deg] for 6: Ge(1)-Cl(1) 2.2124(10); Ge(1)-N(1) 1.988(2);
Ge(1)-N(2) 1.979(2); C(1)-N(1) 1.335(4); C(1)-N(2) 1.330(4); Ge(1)-W(1) 2.4984(3); N(1)-Ge(1)-N(2) 67.77(10); N(1)-
Ge(1)-Cl(1) 99.67(8); N(2)-Ge(1)-Cl(1) 99.58(8); N(1)-Ge(1)-W(1) 124.61(8); N(2)-Ge(1)-W(1) 126.34(8); Cl(1)-Ge(1)-W(1)
˚
124.01(3). Selected bond distances [A] and bond angles [deg] for 7: Ge(1)-Cl(1) 2.2156(6); Ge(1)-N(1) 1.9886(15); Ge(1)-N(2)
1.9810(17); C(1)-N(1) 1.327(2); C(1)-N(2) 1.338(2); Ge(1)-Mo(1) 2.49901(19); N(1)-Ge(1)-N(2) 67.63(6); N(1)-Ge(1)-Cl(1)
99.34(5); N(2)-Ge(1)-Cl(1) 99.31(5); N(1)-Ge(1)-Mo(1) 124.89(5); N(2)-Ge(1)-Mo(1) 126.47(5); Cl(1)-Ge(1)-Mo(1)
124.146(18).
data are in good agreement with the solid-state structure
and the observation of distinct trimethylsilyl and phenyl
groups.
almost linear Ge-M-Ge bond angles, 174° both for 6 and 7.
˚
The W-Ge bond length (2.4984(3) A) is very similar to that
in the closely related chelated complex [{ArNC(t-Bu)NAr}-
10
Ge(Cl)W(CO)5] (2.5564(6) A) (Ar = C6H3i-Pr2-2,6) and
˚
Ge(II) Complexes with Transition Metals. Like N-hetero-
cyclic carbenes, the NHGe are usually regarded as σ-
donors, although the weakness of the NfGe π-donation
could involve the π-acceptor strength when used as ligands
for transition metals. With amidinate as ligand, the p-orbi-
tal of germanium is filled by the coordinative bond from
the imino nitrogen atom which diminishes the Lewis char-
acter of these tricoordinate germylenes. In order to test
their ability to coordinate with transition-metal, complexa-
tions of 2a with [codW(CO)4] (cod = 1,5-cyclooctadiene)
and [nbdMo(CO)4] (nbd = 2,5-norbornadiene) were exam-
ined. Displacement of the ligand (cod or nbd) by two germ-
anium(II) species 2a occurred easily in THF solution
(Scheme 2).
Complexes 6 and 7 were isolated as pale yellow powders in
moderate yields, 22% and 24%, respectively. They were
crystallized from toluene at low temperature to give analy-
tically pure colorless crystals. Their 1H and 13C NMR
spectra showed only small differences from the spectra of
the corresponding germylene except for a slight shift of the
signals of the trimethylsilyl group (Δδ ∼ 0.20 ppm, 1H
NMR). However, it is noteworthy that in the13C NMR
spectrum there is only one carbonyl resonance (210.4 and
210.2 ppm) for 6 and 7, respectively. Furthermore a strong
band in the IR spectrum (1894 and 1903 cm-1) indicates
a “trans” octahedral geometry for these complexes.25 An
X-ray structure study confirmed the “trans” orientation of
the two chloroamidinato germanium fragments in both cases
(Figure 5). Compounds 6 and 7 are the first di(amidinato-
germylene)-tungsten and -molybdenum complexes to be
isolated and structurally characterized. The germanium
atom adopts a distorted tetrahedral geometry, and the
transition metals (W, Mo) are octahedrally coordinated with
to that observed with the β-diketiminato ligand.25 The
same small variations were observed for the Mo-Ge bond
length (2.4990 A) compared to those of the five-membered
˚
N-heterocyclic germylene complex [(NHGe)3Mo(CO)3]
26
˚
(2.5285(2), 2.5445(2), and 2.5452(3) A). The two Ge-N
˚
bonds are shorter (Δ = 0.044-0.081 A) than those of the
starting chlorogermylene. Recently, molybdenum com-
plexes of benzaannulated bisstannylenes were reported.27
In this last case, the two tin(II) centers lie in neighboring
positions probably because of the presence of an alkyl
bridging group through the ring nitrogen atoms.
These results are very encouraging and open up new
perspectives for the involvement of these germanium(II)
compounds as valuable ligands for transition-metal com-
plexes and their applications as new catalysts.
Conclusion
The first bromide and iodide amidinatogermanium(II)
species have been isolated and characterized. Besides the
steric hindrance of the trimethylsilyl groups on the nitrogen
atoms, the presence of a phenyl group on the bridging carbon
is significant. It not only stabilizes the germylenes into their
monomeric forms but also induces a perfect selectivity of the
metalation reaction on Cl2Ge dioxane, giving either mono-
3
amidinato or diamidinato compounds according to the
stoichiometry used. NMR spectroscopic data and single-
crystal X-ray analyses confirm the perfect chelation of this
ligand to the metal center, forming three-coordinate germa-
nium. Moreover, these complexes preserve their specific
reactivity, as was shown in the cycloaddition reaction with
€
(26) Ullah, F.; Kuhl, O.; Bajor, G.; Veszpremi, T.; Jones, P. G.;
Heinicke, J. Eur. J. Inorg. Chem. 2009, 221.
(27) Hahn, F. E.; Zabula, A. V.; Pape, T.; Hepp, A.; Tonner, R.;
Haunschild, R.; Frenking, G. Chem.;Eur. J. 2008, 14, 10716.
(25) Saur, I.; Garcia Alonso, S.; Gornitzka, H.; Lemierre, V.; Chros-
towska, A.; Barrau, J. Organometallics 2005, 24, 2988.

3044 Organometallics, Vol. 29, No. 13, 2010
Matioszek et al.
o-quinone. Their σ-donor character was highlighted by their
easy complexation with transition-metal complexes. For the
first time, two trinuclear bis(germanium(II)) tungsten and
molybdenum complexes were prepared and their structures
elucidated by X-ray single-crystal diffraction studies.
Me3); 125.9 (Cortho); 128.1 (Cmeta); 129.7 (Cpara); 137.3 (Cipso);
181.6 (C6H5-C). 29Si NMR (59.63 MHz, C6D6): δ (ppm) 3.5
(SiMe3). MS m/z (%): [M]þ = 416 (32); [M - Br]þ = 337 (58);
[M - GeBr]þ = 263 (16); [SiMe3]þ = 73 (100). Anal. Calcd for
C13H23BrGeN2Si2: C, 37.53; H, 5.57; N, 6.73. Found: C, 36.93;
H, 5.23; N, 6.18.
[{Me3SiNC(Ph)NSiMe3}2Ge] (3). By using the same proce-
dure as that described for 2a, except the reaction time (20 h at
room temperature then refluxed for 8 h), [{Me3SiNC(Ph)-
Experimental Section
General Procedures. All manipulations with air-sensitive ma-
terials were performed in a dry and oxygen-free atmosphere of
argon by using standard Schlenk-line and glovebox techniques.
Solvents were purified with the MBraun SBS-800 purification
system except THF, which was distilled on Na/benzophenone.
Benzonitrile and hexamethyldisilazane were distilled on potas-
sium hydroxyde and degassed using three consecutive freeze-
pump-thaw cycles and vacuum before storage on molecular
NSiMe3}Li] (4.10 mmol) in diethyl ether (10 mL) and Cl2Ge
3
dioxane (0.48 g, 2.07 mmol) gave 3 as a yellow, sticky solid,
which was crystallized in toluene at -24 °C. Yield: 1.22 g (98%).
1H NMR (300.13 MHz, C6D6): δ (ppm) 0.16 (s, 36H, SiMe3);
6.98-7.03 (m, 6H, CmetaH and CparaH); 7.20 (dd, 3JHH = 7.6 Hz,
4JHH = 1.8 Hz, 4H, CorthoH). 13C{1H} NMR (75.47 MHz,
C6D6): δ (ppm) 1.8 (SiMe3); 127.2 (Cortho); 127.8 (Cmeta); 128.7
(Cpara); 141.6 (Cipso); 174.1 (C6H5-C). 29Si NMR (59.63 MHz,
C6D6): δ (ppm) -1.0 (SiMe3). MS m/z (%): [M]þ = 600 (12);
[M - CH3]þ = 585 (6); [SiMe3]þ = 73 (100). Anal. Calcd for
C26H46GeN4Si4: C, 52.08; H, 7.73; N, 9.34. Found: C, 51.86; H,
8.42; N, 8.94.
˚
sieves (4 A). NMR spectra were recorded with the following
spectrometers: 1H, Bruker Avance II 300 (300.13 MHz) and
Avance II 500 (500.13 MHz); 13C, Bruker Avance II 300 (75.47
MHz) and Avance II 500 (125.77 MHz); 29Si, Bruker Avance II
300 (59.63 MHz) at 298 K. Mass spectra were measured with a
Hewlett-Packard 5989A in the electron impact mode (70 eV).
Melting points were measured with a capillary electrothermal
apparatus. Elemental analyses were done on a Perkin Elmer
2400. IR spectra were measured on a Varian 640-IR FT-IR
Reactivity of 3,5-Di-tert-butylorthoquinone toward 2a (4a). To
a solution of 2a (0.19 g, 0.51 mmol) in toluene (3 mL) was added
a solution of 3,5-di-tert-butylorthoquinone (0.11 g, 0.51 mmol)
in toluene (2 mL). The solution was stirred for 30 min. The
solvent was removed in vacuo to yield 4a as a light brown powder.
Yield: 0.30 g (99%). Crystallization from a mixture of toluene/
THF at -24 °C gave colorless crystals. Mp: 160 °C. 1H NMR
(300.13 MHz, C6D6): δ (ppm) 0.07 (s, 18H, SiMe3); 1.33 (s, 9H,
spectrometer. The germanium(II) derivatives Cl2Ge dioxane28
3
and I2Ge29 were prepared according to literature procedures.
[{Me3SiNC(Ph)NSiMe3}GeCl] (2a). A solution of freshly
prepared lithium benzamidinate [{Me3SiNC(Ph)NSiMe3}Li]
(6.20 mmol) in diethyl ether (7 mL) was added to a suspension
3
C4-C(CH3)3); 1.66 (s, 9H, C6-C(CH3)3); 6.77 (dd, JHH = 8.3
Hz, 4JHH = 1.3 Hz, 2H, CorthoH); 6.88 (t, 3JHH4 = 7.5 Hz, 2H,
CmetaH); 6.94-6.99 (m, 1H, CparaH); 7.05 (d, JHH = 2.3 Hz,
of Cl2Ge dioxane (1.44 g, 6.20 mmol) in diethyl ether (5 mL) at
3
-78 °C. The reaction mixture was warmed to room tempera-
ture, stirred for 2.5 h, and then refluxed for 4 h. The solvents
were removed under reduced pressure, and the residue was
extracted with toluene (50 mL). After filtration on Celite, the
filtrate was concentrated in vacuo to give 2a as a pale yellow
solid. Yield: 2.20 g (95%). Crystallization from a mixture of
toluene/THF at -24 °C gave colorless crystals suitable for X-ray
study. Mp: 60 °C. 1H NMR (300.13 MHz, C6D6): δ (ppm) -0.06
(s, 18H, SiMe3); 6.90-7.03 (m, 5H, C6H5). 13C{1H} NMR
(75.47 MHz, C6D6): δ (ppm) 0.3 (SiMe3); 125.9 (Cortho); 128.1
(Cmeta); 129.7 (Cpara); 137.3 (Cipso); 181.8 (C6H5-C). 29Si NMR
4
1H, C5H); 7.25 (d, JHH = 2.3 Hz, 1H, C3H). 13C{1H} NMR
(75.47 MHz, C6D6): δ (ppm) 0.5 (SiMe3); 29.8 (C6-C(CH3)3);
31.8 (C4-C(CH3)3); 34.4 (C4-C(CH3)3); 34.7 (C6-C(CH3)3); 108.2
(C3); 113.3 (C5); 126.3 (Cortho); 128.2 (Cmeta); 130.1 (Cpara); 131.9
(Cipso); 133.4 (C6); 141.1 (C4); 143.4 (C1); 147.6 (C2); 178.8
(C6H5-C). 29Si NMR (59.63 MHz, C6D6): δ (ppm) 6.2 (SiMe3).
MS m/z (%): [M]þ = 592 (15); [M - CH3]þ = 577 (6); [M -
Cl]þ = 557 (1); [SiMe3]þ = 73 (100). Anal. Calcd for C27H43-
GeClN2O2Si2: C, 54.79; H, 7.32; N, 4.73. Found: C, 54.54.25; H,
7.15; N, 4.32.
(59.63 MHz, C6D6): δ (ppm) 3.0 (SiMe3). MS m/z (%): [M]þ
=
Reactivity of Di-tert-butylorthoquinone toward 2b (4b). By
using the same procedure as that described for 4a, 2b (0.38 g,
0.83 mmol) in toluene (4 mL) and 3,5-di-tert-butylorthoquinone
(0.18 g, 0.83 mmol) in toluene (3 mL) gave 4b as a brown
powder. Yield: 0.56 g (99%). Mp: 77 °C. 1H NMR (300.13
MHz, C6D6): δ (ppm) 0.10 (s, 18H, SiMe3); 1.33 (s, 9H, C4-
C(CH3)3); 1.70 (s, 9H, C6-C(CH3)3); 6.79-6.80 (m, 2H,
CorthoH); 6.85-6.94 (m, 2H, CmetaH); 6.99-7.03 (m, 1H,
372 (13); [M - Cl ]þ = 337 (6); [M - GeCl ]þ = 263 (13);
[SiMe3]þ = 73 (100). Anal. Calcd for C13H23ClGeN2Si2: C,
42.02; H, 6.24; N, 7.54. Found: C, 41.52; H, 6.19; N, 7.07.
[{Me3SiNC(Ph)NSiMe3}GeI] (2b). By using the same proce-
dure as that described for 2a, [{Me3SiNC(Ph)NSiMe3}Li] (6.20
mmol) in diethyl ether (7 mL) and I2Ge (2.03 g, 6.20 mmol) in
diethyl ether (15 mL) gave 2b as a yellow solid. Yield: 2.83 g
4
4
1
CparaH); 7.12 (d, JHH = 2.2 Hz, 1H, C5H); 7.32 (d, JHH
=
(98%). Mp: 82 °C. H NMR (300.13 MHz, C6D6): δ (ppm)
2.2 Hz, 1H, C3H). 13C{1H} NMR (75.47 MHz, C6D6): δ (ppm)
0.7 (SiMe3); 29.9 (C6-C(CH3)3); 31.7 (C4-C(CH3)3); 34.4 (C4-
C(CH3)3); 34.8 (C6-C(CH3)3); 108.3 (C3); 113.5 (C5); 126.3
(Cortho); 128.2 (Cmeta); 129.9 (Cpara); 132.1 (Cipso); 133.5 (C6);
141.2 (C4); 143.3 (C1); 147.5 (C2); 177.7 (C6H5-C). 29Si
NMR (59.63 MHz, C6D6): δ (ppm) 6.4 (SiMe3). MS m/z (%):
[M - I]þ = 557 (4); [SiMe3]þ = 73 (100). Anal. Calcd for
(C27H43GeIN2O2Si2): C, 47.46; H, 6.34; N, 4.10. Found: C,
47.67; H, 6.41; N, 3.71.
-0.03 (s, 18H, SiMe3); 6.87-6.98 (m, 5H, C6H5). 13C{1H} NMR
(75.47 MHz, C6D6): δ (ppm) 0.0 (SiMe3); 125.5 (Cortho); 127.8
(Cmeta); 129.5 (Cpara); 137.0 (Cipso); 180.4 (C6H5-C). 29Si NMR
(59.63 MHz, C6D6): δ (ppm) 4.0 (SiMe3). MS m/z (%): [M]þ
=
464 (1); [M - I]þ = 337 (25); [M - GeI]þ = 263 (17); [SiMe3]þ =
73 (100). Anal. Calcd for C13H23GeIN2Si2: C, 33.72; H, 5.01; N,
6.05. Found: C, 33.93; H, 5.19; N, 5.45.
[{Me3SiNC(Ph)NSiMe3}GeBr] (2c). An excess of trimethyl-
silyl bromide (0.20 mL, 1.50 mmol) was added to a suspension of
2a (0.20 g, 0.54 mmol) in toluene (5 mL). The mixture was stirred
for 24 h. The volatiles were removed in vacuo, giving quantita-
tively 2c as a white solid. Crystallization from toluene at -24 °C
gave colorless crystals. Mp: 53 °C. 1H NMR (300.13 MHz,
C6D6): δ (ppm) -0.04 (s, 18H, SiMe3); 6.92-6.99 (m, 5H,
C6H5). 13C{1H} NMR (75.47 MHz, C6D6): δ (ppm) 0.3 (Si-
Reactivity of Di-tert-butylorthoquinone toward 2c (4c). By
using the same procedure as that described for 4a, except the
reaction time (40 min), 2c (0.21 g, 0.50 mmol) in toluene (3 mL)
and 3,5-di-tert-butylorthoquinone (0.11 g, 0.50 mmol) in to-
luene (3 mL) gave 4c quantitatively as a yellow-green powder.
1
Mp: 154 °C. H NMR (300.13 MHz, C6D6): δ (ppm) 0.10 (s,
18H, SiMe3); 1.35 (s, 9H, C4-C(CH3)3); 1.72 (s, 9H, C6-
C(CH3)3); 6.74-6.84 (m, 4H, CorthoH, CmetaH); 6.88-6.94
(m, 1H, CparaH); 7.12 (d, JHH = 2.3 Hz, 1H, C5H); 7.33 (d,
4
(28) Mironov, V. F.; Gar, T. K. Kh. Obshch. Khim. 1975, 45, 103.
(29) Foster, L. S. Inorg. Synth. 1950, 63.
4JHH = 2.3 Hz, 1H, C3H). 13C{1H} NMR (75.47 MHz, C6D6): δ

Article
Organometallics, Vol. 29, No. 13, 2010 3045
Table 1. Crystal Data and Structure Refinements of Complexes 2a,c, 3, 4a, and 5-7
2a
2c
3
4a
empirical formula
fw (g/mol)
temp (K)
C13H23ClGeN2Si2
371.55
193(2)
monoclinic
P21/c
12.4571(3)
10.7366(2)
14.8710(3)
90
110.190(1)
90
1866.73(7)
4
1.322
1.903
768
C13H23BrGeN2Si2
416.01
193(2)
monoclinic
P21/c
12.5760(6)
10.7725(6)
15.0109(8)
90
110.286(3)
90
1907.46(17)
4
1.449
3.817
840
C26H46GeN4Si4
599.62
193(2)
orthorhombic
P212121
11.4651(2)
12.8058(2)
23.5802(4)
90
90
90
3462.04(10)
4
1.150
1.043
1272
C27H43ClGeN2O2Si2
591.85
193(2)
orthorhombic
Pna21
18.8621(3)
14.8137(2)
11.2794(2)
90
90
90
3151.66(9)
4
1.247
1.157
1248
cryst syst
space group
˚
a (A)
˚
b (A)
˚
c (A)
R (deg)
β (deg)
γ (deg)
3
˚
volume (A )
Z
density calcd (g/cm3)
absorp coeff (mm-1
F(000)
)
θ
max (deg)
28.28
34 119/4602
0.0551
26.37
29 815/3870
0.1011
28.28
56 792/8489
0.0608
25.34
29 818/5678
0.0537
reflns collected/unique
Rmerge
data/restraints/params
goodness-of-fit
4602/207/252
1.221
3870/238/252
1.224
8489/0/328
0.991
5678/1/328
1.019
R indices [I>2(σ)I]
wR2 = 0.1478
R1 = 0.0631
wR2 = 0.1538
R1 = 0.0825
0.401, -0.860
wR2 = 0.1341
R1 = 0.0587
wR2 = 0.1454
R1 = 0.0946
0.571, -0.502
wR2 = 0.0678
R1 = 0.0333
wR2 = 0.0727
R1 = 0.0484
0.331, -0.193
wR2 = 0.0718
R1 = 0.0326
wR2 = 0.0759
R1 = 0.0420
0.436, -0.257
R indices (all data)
-3
˚
largest diff peak and hole (e A
)
5
6
7
empirical formula
fw (g/mol)
temp (K)
C40H66GeN4O2Si4
819.92
193(2)
C30H46Cl2Ge2N4O4 Si4W
1039.00
193(2)
C30H46Cl2Ge2MoN4O4Si4
951.09
193(2)
cryst syst
space group
orthorhombic
Pna21
19.9585(6)
21.4419(6)
11.2036(3)
90
90
90
4794.6(2)
4
1.136
monoclinic
C2/c
29.3454(5)
9.2756(2)
19.3970(3)
90
124.3860(10)
90
4357.15(14)
4
1.584
monoclinic
C2/c
29.3886(5)
9.2725(2)
19.4268(4)
90
124.4100(10)
90
4367.56(15)
4
1.446
˚
a (A)
˚
b (A)
˚
c (A)
R (deg)
β (deg)
γ (deg)
3
˚
volume (A )
Z
density calcd (g/cm3)
absorp coeff (mm-1
F(000)
)
0.773
1752
4.272
2056
1.918
1928
θ
max (deg)
26.37
72 086/9718
0.1568
30.03
28508/6304
0.0459
30.51
34 688/6623
0.0482
reflns collected/unique
Rmerge
data/restraints/parameters
goodness-of-fit
9718/37/503
1.009
6304/0/219
1.014
6623/0/219
1.008
R indices [I>2(σ)I]
wR2 = 0.0827
R1 = 0.0504
wR2 = 0.0982
R1 = 0.0997
0.287, -0.329
wR2 = 0.0632
R1 = 0.0300
wR2 = 0.0688
R1 = 0.0451
1.760, -0.543
wR2 = 0.0707
R1 = 0.0303
wR2 = 0.0787
R1 = 0.0480
0.572, -0.400
R indices (all data)
-3
˚
largest diff. peak and hole (e A
)
(ppm) 0.5 (SiMe3); 29.8 (C6-C(CH3)3); 31.7 (C4-C(CH3)3); 34.4
(C4-C(CH3)3); 34.8 (C6-C(CH3)3); 108.3 (C3); 113.5 (C5); 126.4
(Cortho); 128.1 (Cmeta); 129.9 (Cpara); 132.1 (Cipso); 133.6 (C6);
141.3 (C4); 143.4 (C1); 147.5 (C2); 178.3 (C6H5-C). 29Si NMR
C6H5); 7.43-7.45 (m, 1H, C6H5). 13C{1H} NMR (75.47 MHz,
C6D6): δ (ppm) 1.0, 1.5, 1.7 (SiMe3); 31.8 (C6-C(CH3)3); 31.9
(C4-C(CH3)3); 34.3 (C4-C(CH3)3); 35.0 (C6-C(CH3)3); 109.3
(C3); 111.4 (C5); 126.2, 126.6, 126.7, 126.8, 127.9, 128.1, 128.3,
128.4, 128.9, 129.1 (C6H5); 131.3 (C6); 136.2 and 136.3 (Cipso);
138.9 (C4); 147.6 (C1); 149.8 (C2); 176.6 and 178.1 (C6H5-C). 1H
NMR (THF-d8): δ (ppm) -0.40 (s, 9H, SiaMe3), -0.21 (s, 9H,
SibMe3), 0.04 (s, 9H, SicMe3), 0.09 (s, 9H, SidMe3); 1.26 (s, 9H,
C4-C(CH3)3); 1.50 (s, 9H, C6-C(CH3)3); 6.57 (d, 4JHH = 2.3 Hz,
(59.63 MHz, C6D6): δ (ppm) 6.2 (SiMe3). MS m/z (%): [M]þ
=
636 (50); [M - CH3]þ = 621 (21); [SiMe3]þ = 73 (100). Anal.
Calcd for C27H43BrGeN2O2Si2: C, 50.96; H, 6.81; N, 4.40.
Found: C, 50.92; H, 6.99; N, 4.22.
Reactivity of Di-tert-butylorthoquinone toward 3 (5). By using
the same procedure as that described for 4a, except the reaction
time (1 h), 3 (0.27 g, 0.44 mmol) in diethyl ether (4 mL) and 3,5-
di-tert-butylorthoquinone (0.10 g, 0.44 mmol) in diethyl ether (3
4
1H, C5H); 6.67 (d, JHH = 2.3 Hz, 1H, C3H); 7.27-7.22 (m,
10H, C6H5). 13C{1H} NMR (75.47 MHz, THF-d8): δ (ppm) 1.5
(SiaMe3); 2.0 (SibMe3); 2.1 and 2.3 (Sic,dMe3); 31.3 (C6-C-
(CH3)3); 32.6 (C4-C(CH3)3); 35.1 (C4-C(CH3)3); 35.7 (C6-C-
(CH3)3); 109.7 (C3); 111.8 (C5); 127.7, 128.1, 128.2, 128.9,
129.1, 129.1, 129.4, 129.5, 130.3, 130.6 (C6H5); 131.9 (C6);
137.2 and 137.3 (Cipso); 139.2 (C4); 148.5 (C1); 150.6 (C2);
177.8 and 179.5 (C6H5-C). 29Si NMR (59.63 MHz, C6D6): δ
1
mL) gave quantitatively 5 as a green powder. Mp: 170 °C. H
NMR (300.13 MHz, C6D6): δ (ppm) -0.10, 0.00, 0.14, and
0.19 (s, 36H, SiMe3); 1.43 (s, 9H, C4-C(CH3)3); 1.87 (s, 9H,
C6-C(CH3)3); 6.95-6.99 (m, 6H, C6H5); 7.01 (d, 4JHH = 2.3 Hz,
1H, C5H); 7.21 (d, 4JHH = 2.2 Hz, 1H, C3H); 7.26-7.32 (m, 3H,

3046 Organometallics, Vol. 29, No. 13, 2010
Matioszek et al.
(ppm) 0.4, 0.6, 1.1, 3.0 (SiMe3). MS m/z (%): [M]þ = 820 (27);
[M - CH3]þ = 805 (1); [SiMe3]þ = 73 (100). HRMS C40H66Ge-
N4O2Si4: calcd mass 820.3484, measured mass 820.3479.
(ppm) 0.13 (s, 36H, SiMe3); 6.81-6.87 (m, 4H, C6H5); 6.89-
6.92 (m, 3H, C6H5); 6.96-6.99 (m, 3H, C6H5). 1H NMR (300.13
MHz, THF-d8): δ (ppm) 0.10 (s, 36H, SiMe3); 7.49-7.51 (m, 4H,
C6H5); 7.52-7.54 (m, 3H, C6H5); 7.55-7.56 (m, 3H, C6H5).
13C{1H} NMR (75.47 MHz, THF-d8): δ (ppm) -0.5 (SiMe3);
126.7 (Cortho); 128.5 (Cmeta); 130.5 (Cpara); 134.9 (Cipso); 181.7
(C6H5-C); 210.2 (CO). 29Si NMR (59.63 MHz, THF-d8): δ
(ppm) 5.6 (SiMe3). MS m/z (%): [M]þ = 952 (1); [M -
2CO]þ = 896 (1); [M - 3CO]þ = 868 (1); [M - 4CO]þ = 840
(1); [SiMe3]þ = 73 (100). IR (KBr pellet) ν (cm-1) 1903 (s) (CO).
Anal. Calcd for C30H46Cl2Ge2MoN4O4Si4: C, 37.88; H, 4.87; N,
5.89. Found: C, 38.34; H, 4.97; N, 5.71.
[{{Me3SiNC(Ph)NSiMe3}Ge(Cl)}2W(CO)4] (6). A solution of
tetracarbonyl(1,5-cyclooctadiene)tungsten (0.22 g, 0.54 mmol)
in THF (10 mL) was added to a solution of 2a (0.40 g, 1.08
mmol) in THF (10 mL) at -78 °C. The reaction mixture was
warmed to room temperature and stirred at 60 °C for 4 h. The
volatiles were removed under reduced pressure, leading to 6
after crystallization from toluene at 4 °C to give yellow crystals.
Yield: 0.12 g (22%). Mp: 190 °C. 1H NMR (300.13 MHz, C6D6):
δ (ppm) 0.14 (s, 36H, SiMe3); 6.82-6.86 (m, 4H, C6H5);
6.88-6.91 (m, 3H, C6H5); 6.95-6.99 (m, 3H, C6H5). 1H NMR
(500.13 MHz, THF-d8): δ (ppm) 0.10 (s, 36H, SiMe3); 7.49-7.51
(m, 4H, C6H5); 7.52-7.54 (m, 3H, C6H5); 7.56-7.57 (m, 3H,
C6H5). 13C{1H} NMR (125.77 MHz, THF-d8): δ (ppm) -0.5
(SiMe3); 126.7 (Cortho); 128.5 (Cmeta); 130.6 (Cpara); 134.9
(Cipso); 182.1 (C6H5-C); 210.4 (CO). 29Si NMR (59.63 MHz,
THF-d8): δ (ppm) 5.7 (SiMe3). IR (KBr pellet): ν (cm-1) 1894 (s)
and 1941 (sh) (CO). Anal. Calcd for C30H46Cl2Ge2N4O4Si4W:
C, 34.68; H, 4.46; N, 5.39. Found: C, 34.62; H, 4.41; N, 5.22.
[{{Me3SiNC(Ph)NSiMe3}Ge(Cl)}2Mo(CO)4] (7). By using the
same procedure as that described for 6, (bicyclo[2.2.1]hepta-2,5-
diene)tetracarbonylmolybdenum (0.16 g, 0.54 mmol) and
2a (0.40 g, 1.08 mmol) gave 7 as pale yellow crystals. Yield:
0.12 g (24%). Mp: 140 °C dec. 1H NMR (300.13 MHz, C6D6): δ
X-ray Structure Determinations. X-ray data (Table 1) were
collected at low temperature (193(2) K) using an oil-coated
shock-cooled crystal on a Bruker-AXS APEX II diffractometer
˚
with Mo KR radiation (λ = 0.71073 A). The structures were
solved by direct phase determination (SHELXS-97)30 and re-
fined for all non-hydrogen atoms by full-matrix least-squares
methods on F2 and subjected to anisotropic refinement.31
Acknowledgment. The authors thank the Centre Na-
tional de la Recherche Scientifique (CNRS, ANR-08-
BLAN-0105-01) for financial support. D.M. is grateful
ꢁ
to the Ministere de l’Enseignement Superieur et de la
Recherche for his Ph.D. grant.
ꢀ
Supporting Information Available: CIF files for the structural
determinations of compounds 2a, 2c, 3, 4a, 5, 6, 7, and
[{H(Me3Si)NC(Ph)N(SiMe3)H}þI-]. These materials are avail-
able free of charge via the Internet at http://pubs.acs.org.
(30) Sheldrick, G. M. SHELXL-97, Program for Crystal Structure
€
Refinement; University of Gottingen, 1997.
(31) Sheldrick, G. M. Acta Crystallogr. 1990, A46, 467.