In search of cationic germanium(II)-transition metal complexes L 2Ge+W(CO)5 and L2Ge+W(CO) 4Ge+L2

Article abstract of DOI:10.1021/om050214v

New germaniumd (II)-tungsten complexes [L²(X)Ge] _nW(CO)_6-n (L² = NPhC(Me)CHC(Me)NPh, n = 1, X = OTf (2); n = 2, X = Cl (13)) have been synthesized and characterized by X-ray crystallography. In compound 2 the triflate was found to be very weakly coordinating to the germanium in the solid state, and this result is confirmed by DFT calculations. All the spectroacopic data are consistent with the L ²(X)Ge ligands being good σ-donors and poor π-acceptors in these complexes, similar to the phosphine ligands in homologous R₃P complexes. Starting from the chlorogermanium(II)-tungsten complexes (L ²(Cl)Ge)_nW(CO)_6-n (n = 1 (1), n = 2 (13)), metathesis reactions with halide or weakly coordinating anions A" (A ^- = TfO^-, BPh₄-, PF₆^-) have been investigated as a general approach to obtain the cationic germanium species [L²Ge⁺]_nW(CO)_6-n. In the case of A^- = TfO^-, spontaneous dissociation of the anion leading to an equilibrium between a neutral and a cationic tetracoordinated germanium species is observed in coordinating solvents. Treatment of L ²(X)Ge with MX₃ (M = Ga, X = Cl; M = In, X = I) afforded the neutral complexes L²MX₂ (M = Ga (7) and In (8)) by ligand transfer reactions. The crystal structure of 8 was determined by X-ray structure analysis.

Full text of DOI:10.1021/om050214v

2988
Organometallics 2005, 24, 2988-2996
In Search of Cationic Germanium(II)-Transition Metal
Complexes L2Ge+W(CO)5 and L2Ge+W(CO)4Ge+L2
Isabelle Saur,† Sonia Garcia Alonso,† Heinz Gornitzka,† Virginie Lemierre,‡
Anna Chrostowska,‡ and Jacques Barrau*,†
Laboratoire He´te´rochimie Fondamentale et Applique´e, UMR 5069, Universite´ Paul Sabatier,
118, Route de Narbonne, F-31062 Toulouse Cedex 04, France, and Laboratoire de Chimie
The´orique et Physico-Chimie Mole´culaire, UMR 5624, FR 2606, Universite´ de Pau et des Pays
de l’Adour, Avenue de l’Universite´, BP 1159, F-64013 Pau Cedex, France
Received March 21, 2005
New germanium(II)-tungsten complexes [L2(X)Ge]nW(CO)6-n (L2 ) NPhC(Me)CHC(Me)-
NPh, n ) 1, X ) OTf (2); n ) 2, X ) Cl (13)) have been synthesized and characterized by
X-ray crystallography. In compound 2 the triflate was found to be very weakly coordinating
to the germanium in the solid state, and this result is confirmed by DFT calculations. All
the spectroscopic data are consistent with the L2(X)Ge ligands being good σ-donors and poor
π-acceptors in these complexes, similar to the phosphine ligands in homologous R3P
complexes. Starting from the chlorogermanium(II)-tungsten complexes (L2(Cl)Ge)nW(CO)6-n
(n ) 1 (1), n ) 2 (13)), metathesis reactions with halide or weakly coordinating anions A-
-
-
(A- ) TfO-, BPh4 , PF6 ) have been investigated as a general approach to obtain the cationic
germanium species [L2Ge+]nW(CO)6-n. In the case of A- ) TfO-, spontaneous dissociation
of the anion leading to an equilibrium between a neutral and a cationic tetracoordinated
germanium species is observed in coordinating solvents. Treatment of L2(X)Ge with MX3
(M ) Ga, X ) Cl; M ) In, X ) I) afforded the neutral complexes L2MX2 (M ) Ga (7) and In
(8)) by ligand transfer reactions. The crystal structure of 8 was determined by X-ray structure
analysis.
Introduction
Like cationic transition metal phosphenium complexes,
the analogous M14(II)-transition metal complexes are
of potential interest for many applications (e.g., as
catalysts for cationic or ring-opening polymerizations)
because of the possibility that the increased electrophi-
licity that results from the positive charge may enhance
substrate coordination and activation. Ligands with
nitrogen donors, particularly â-diketiminato ligands L2,
are well-suited for stabilizing neutral germanium(II)
species such as L2(X)Ge (X ) Cl, I)5 and the related
complexes L2(Cl)GeY (Y ) S, Se)6 and L2(X)GeM′Ln
(M′Ln ) W(CO)5, X ) Cl, I; M′Ln ) Fe(CO)4, X ) Cl),2h,j
as well as cationic germanium(II) derivatives L2Ge+.3i
In a previous paper, we showed that the three-
coordinate germanium compounds L2(X)Ge are best
described by a model structure corresponding to a
During the past few years, the chemistry of stable
homoleptic and heteroleptic divalent compounds of
germanium1 and of their transition metal complexes2
has been the focus of considerable attention. A variety
of such compounds have been reported, but very little
has been published on cationic germanium(II) deriva-
tives3 RGe+. Similarly, except the pioneering work of
Filippou4 concerning the cationic germylidyne complex
trans-[(MeCN)(dppe)2WtGe(η1-Cp*)]+[B(C6F5)4]-, to our
knowledge no other studies have dealt with cationic
germanium(II)-transition metal complexes RGe+M′Ln,
probably because of the absence of suitable precursors.
* To whom correspondence should be addressed. E-mail:
barrau@chimie.ups-tlse.fr. Fax: +33561558204. Phone: +33561556172.
† Universite´ Paul Sabatier.
divalent germanium species weakly coordinated with
‡ Universite´ de Pau et des Pays de l’Adour.
- 5c
(1) Recent reviews: (a) Ku¨hl, O. Coord. Chem. Rev. 2004, 248, 411.
(b) Barrau, J.; Rima, G. Coord. Chem. Rev. 1998, 178, 593. (c) Dias,
H. V. R.; Wang, Z.; Jin, W. Coord. Chem. Rev. 1998, 176, 67. (d) Driess,
M.; Gru¨tzmacher, H. Angew. Chem. 1996, 108, 900; Angew. Chem.,
Int. Ed. Engl. 1996, 35, 827. (e) Neumann, W. P. Chem. Rev. 1991,
91, 311. (f) Lappert, M. F.; Rowe, R. S. Coord. Chem. Rev. 1990, 100,
267. (e) Satge´, J. J. Organomet. Chem. 1990, 400, 121.
the halide group L2Ge+‚‚‚X
.
Following our work on
the corresponding â-diketiminato halogermanium(II)-
(3) (a) Harrison, P. G. In Comprehensive Coordination Chemistry;
Wilkinson, G., Gillard, D., McCleverty, J. A., Eds.; Pergamon: Oxford,
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F.; Rowe, R. S. Coord. Chem. Rev. 1990, 100, 267. (e) Jastrzebski, J.
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nometallics 2000, 19, 4613. (g) Agustin, D.; Rima, G.; Gornitzka, H.;
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Gornitzka, H.; Barrau, J. Eur. J. Inorg. Chem. 2000, 693. (i) Bibal, C.;
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10.1021/om050214v CCC: $30.25 © 2005 American Chemical Society
Publication on Web 05/06/2005

Cationic Ge(II)-Transition Metal Complexes
Organometallics, Vol. 24, No. 12, 2005 2989
Scheme 1
(3) in THF (method a) and (ii) direct treatment of the
germanium complex L2(Cl)GeW(CO)5 (1) with AgOTf in
toluene (method b).
(a) L2(OTf)Ge (3). Compound 3 was obtained in high
yield from a metathesis reaction between L2(Cl)Ge (4)
and AgOTf in toluene at room temperature, as a light
yellow air- and moisture-sensitive solid, soluble in polar
and aromatic solvents. The EI (70 eV) mass spectrum
shows a base peak corresponding to [L2Ge]+; the pres-
ence of the molecular ion M+• with a relative intensity
of 45% suggests that the triflate group is relatively
strongly bound to germanium, indicating some degree
of ion pairing in the gas phase. The chemical shifts of
Scheme 2
1
the methine and methyl groups in the H NMR spec-
trum (CDCl3, δMe ) 2.07 ppm, δCH ) 5.66 ppm) lie
slightly downfield from the corresponding resonances
in the halides 4 and 5 (L2(X)Ge, X ) Cl and I,
respectively) (CDCl3, δMe ) 1.96 (4), 2.05 (5); δCH ) 5.39
(4), 5.64 (5)).5a
This may be an indication of an increased positive
charge on the germanium. The infrared spectrum (C6D6)
exhibits several ν(CF3SO3) absorptions between 1368
and 1000 cm-1; the highest frequency band is the
strongest and is characteristic of a monodentate-co-
valently bound triflate (ν ) 1365-1395 cm-1 for co-
valently bound triflate; ν ) 1270-1280 cm-1 for ionic
bound triflate).7 Interestingly, two ν(SO3) bands are
observed at 1367.4 cm-1 (weak) and 1271.7 cm-1 (very
strong) for 3 in pyridine solvent, suggesting an equilib-
rium between covalent and ionic forms.
transition metal complexes L2(X)GeW(CO)5 (X ) Cl, I,
L2 ) PhNC(Me)CH(Me)NPh),2j we have sought to
develop synthetic routes to the mono[cationic-germa-
nium(II)]- and bis[cationic-germanium(II)]-transition
metal complexes L2Ge+W(CO)5 and (L2Ge+)2W(CO)4,
respectively.
In this paper, we describe the results of our first
approach to the synthesis of these compounds, which
involves replacement of the halide ligand in haloger-
manium(II)-transition metal complexes [L2(X)Ge]xM′Ln-x
through anion metathesis with the salts of weakly
coordinating anions (F3CS(O)2O-, BPh4-, PF6-) (Scheme
1).
(b) L2(TfO)GeW(CO)5. The tungsten complex L2-
(TfO)GeW(CO)5 (2) was obtained in good yields by both
methods (a) and (b) (Scheme 2). Complex 2 is a yellow
air- and moisture-sensitive solid, soluble in polar and
aromatic solvents and insoluble in pentane. It has been
1
fully characterized by H, 13C, and 19F NMR, IR, and
mass spectrocopies. The complex shows low thermal
stability, as indicated by decomposition at its melting
point of 119-123 °C and by the EI (70 eV) mass
spectrum, which displays a just-detectable molecular ion
peak [M]+• (intensity <0.1% of the [L2Ge]+ base peak)
in addition to fragmentations characteristic of such
structures, such as facile successive losses of the car-
bonyl groups and loss of the weakly coordinating triflate
group, giving rise to a strong peak due to the [L2GeW-
(CO)5]+ ion. The 1H, 13C, and 19F NMR spectra of 2
feature signals with chemical shifts downfield from
those of the germanium(II) compound 3, suggesting
diminution of the electronic density on the L2(TfO)Ge
ligand due to bonding with the W(CO)5 fragment.
Compared to the halide complexes L2(X)GeW(CO)5 (X
) Cl, 1; X ) I, 6)2j (CDCl3: δMe ) 2.02 (1), 2.01 (6), 2.11
(2); δCH ) 5.56 (1), 5.82 (6), 5.85 (2) ppm), all the
Results and Discussion
1. Attempted Synthesis of L2Ge+W(CO)5. 1.1. L2-
(OTf)GeW(CO)5. Our first attempts were directed at
triflate-substituted germanium(II) complexes in search
of evidence for dissociation of the triflate group (TfO-),
and so we examined the preparation of the triflate
germanium(II)-tungsten complex L2(TfO)GeW(CO)5 (2).
Two alternative synthetic methods were investigated
(Scheme 2): (i) treatment of photochemically produced
W(CO)5‚THF with the germanium(II) triflate L2Ge(OTf)
(5) (a) Akkari, A.; Byrne, J. J.; Saur, I.; Rima, G.; Gornitzka, H.;
Barrau, J. J. Organomet. Chem. 2001, 622, 190. (b) Chrostowska, A.;
Lemierre, V.; Pigot, T.; Pfister-Guillouzo, G.; Saur, I.; Miqueu, K.;
Rima, G.; Barrau, J. Main Group Met. Chem. 2002, 25, 469. (c) Saur,
I.; Miqueu, K.; Rima, G.; Gornitzka, H.; Barrau, J.; Lemierre, V.;
Chrostowska, A.; Sotiropoulos, J. H.; Pfister-Guillouzo, G. Organome-
tallics 2003, 22, 3143. (d) Ayers, A. E.; Klapo¨tke, T. M.; Dias, H. V. R.
Inorg. Chem. 2001, 40, 1000. (e) Ding, Y.; Roesky, H. W.; Noltemeyer,
M.; Schmidt, H. G.; Power, P. P. Organometallics 2001, 20, 1190. (f)
Ding, Y.; Hao, H.; Roesky, H. W.; Noltemeyer, M.; Schmidt, H. G.
Organometallics 2001, 20, 4806. (g) Ding, Y.; Ma, Q.; Roesky, H. W.;
Herbst-Irmer, R.; Uson, I.; Noltemeyer, M.; Schmidt, H. G. Organo-
metallics 2002, 21, 5216.
1
corresponding H NMR resonances due to the protons
in 2 appear at downfield positions. This observation
reflects the lower coordinating ability of the anion TfO-
compared to Cl- and I-, suggesting that the triflate
group is weakly bound to the germanium. The two 13C
NMR chemical resonances for the CO groups and three
bands in the carbonyl region of the IR spectrum are
characteristic of C4v local symmetry around the tungsten
in 2. The IR spectrum of the complex 2 determined in
(6) (a) Ding, Y.; Ma, Q.; Uso¨n, I.; Roesky, H. W.; Noltemeyer, M.;
Schmidt, H. G. J. Am. Chem. Soc. 2002, 124, 8542. (b) Saur, I.; Miqueu,
K.; Rima, G.; Gornitzka, H.; Barrau, J. Organometallics 2003, 22, 1106.
(7) (a) Lawrance, G. A. Chem. Rev. 1986, 86, 17. (b) Lee, K. E.; Arif,
A. M.; Gladysz, J. A. Organometallics 1991, 10, 751.

2990 Organometallics, Vol. 24, No. 12, 2005
Saur et al.
Scheme 3
Table 1. Crystallographic Data for 2 and 13
2
13
empirical formula
fw
C
23H17F3GeN2O8SW
C38H34Cl2Ge2N4O4W
1010.62
794.95
cryst syst
space group
unit cell dimens
a (Å)
orthorhombic
Pnma
monoclinic
P21/c
16.970(2)
19.859(2)
9.587(10)
10.480(1)
9.542(1)
19.334(3)
2
1881.5(4)
2
1.784
b (Å)
c (Å)
â (deg)
V (Å3)
3230.7(6)
4
1.824
Z
Dcalc (Mg m-3
)
no. of reflns collected
no. of indep reflns
no. of params
17 367
3405
12 712
3835
356
234
R1 [I > 2σ(I)]
0.0216
0.0539
0.713 and -0.746
0.0275
0.0567
1.225 and -0.531
wR2 [all data]
largest diff peak and hole (e‚Å-3
)
C6D6 or CDCl3 solution contains a strong band at ∼1366
cm-1 (C6D6: 1365.4 cm-1; CDCl3: 1366.5 cm-1), which
is in the typical range for a covalent triflate.7 As in the
case of the starting material 3, in pyridine solvent two
bands were detected at 1379.1 cm-1 (weak) and 1274.0
cm-1 (very strong) in the ν(CF3SO3) region; this is
probably the result of an equilibrium between the
pyridine-free neutral germanium(II)-tungsten complex
and the corresponding pyridine-coordinated ionic com-
plex, pushed toward the ionic side by the electron-
releasing solvent. The equilibrium is not completely
shifted to the ionic form; this is evident also from the
1H NMR spectrum in pyridine-d5, which features two
signals each (30/70%) for the methine and methyl
protons (C5D5N: 1H δMe: 1.77, 2.11 ppm; δCH: 5.12, 5.32
ppm).
Suitable crystals of 2 for crystallographic analysis
were obtained from toluene at -35 °C. The molecular
structure is depicted in Figure 1, while the pertinent
crystallographic data are given in Table 1.
The single-crystal X-ray analysis of 2 reveals that in
the solid state the molecular structure of 2 is very
similar to that of 1, with the germanium taking a
distorted tetrahedral configuration (the sum of the
N(1)-Ge-N(1)A, N(1)-Ge-O(4), O(4)-Ge-W, W-Ge-
N(1)A bond angles is 432.05°) and bound covalently to
the triflate ligand. The geometry around the tungsten
is nearly octahedral, and the â-diketiminate ligand is
symmetrically bound to the germanium atom. The
Ge-W bond in 2 is shorter (2.55 Å) than typical Ge-W
single bonds (2.59-2.67 Å)8 and is also slightly shorter
than those in the halogenated complexes 1 and 6 (1, 2.57
Å; 6, 2.57 Å),2j which are among the shortest reported
for compounds of the R2GeW(CO)5 type.8,9 In comparison
with the Ge-O distances (2.020-2.48 Å) reported for
R(TfO)Ge(II) or R2(TfO)(Σ)Ge(IV) compounds with very
weakly binding triflate,4h,7b,10 the Ge-O bond distance
in 2 (2.04 Å) is slightly shorter and in the same range
Figure 1. Solid-state structure of L2(OTf)GeW(CO)5 (2)
(ellipsoids are drawn at the 50% probability level). Hydro-
gen atoms are omitted for clarity. Selected bond lengths
(Å) and bond angles (deg): Ge-O(4) 2.044(7), Ge-N(1)
1.891(2), Ge-N(1A) 1.891(2), Ge-W 2.5473(5), W-C(12)
1.995(5), W-C(10) 2.044(3), W-C(11) 2.036(4), O(4)-S
1.475(9), S-O(5) 1.421(7), S-O(6) 1.421(9), C(12)-O(3)
1.142(6), C(10)-O(1) 1.135(4), C(11)-O(2) 1.135(4), N(1)-
Ge-N(1A) 94.93(16), N(1)-Ge-O(4) 98.7(3), N(1A)-Ge-
O(4) 86.8(3), N(1)-Ge-W 127.82(8), N(1A)-Ge-W 127.82-
(8), O(4)-Ge-W 110.6(3), Ge-W-C(12) 179.71(13), Ge-
W-C(11) 88.51(10), Ge-W-C(10) 92.80(9).
(8) (a) Figge, L. K.; Caroll, P. J.; Berry, D. H. Angew. Chem., Int.
Ed. Engl. 1996, 35, 435. (b) Ueno, K.; Yamagushi, K.; Ogino, H.
Organometallics 1999, 18, 4468. (c) Renner, G.; Kircher, P.; Huttner,
G.; Rutsch, P.; Heinze, K. Eur. J. Inorg. Chem. 2000, 879.
(9) (a) Jutzi, P.; Hampel, B.; Stroppel, K.; Angermud, K.; Hofmann,
P. Chem. Ber. 1985, 118, 2789. (b) Jutzi, P.; Hampel, B.; Hursthouse,
B. M.; Howes, A. J. J. Organomet. Chem. 1986, 299, 19. (c) Du Mont,
W. W.; Lange, L.; Pohl, S.; Saak, W. Organometallics 1990, 9, 1395.
(d) Huttner, G.; Weber, U.; Sigwarth, B.; Scheidstger, O.; Lang, H.;
Zsolnai, L. J. Organomet. Chem. 1985, 282, 331.
(10) (a) Ayers, A. E.; Dias, H. V. Inorg. Chem. 2002, 41, 3259. (b)
Dias, H. V. R.; Wang, Z. Inorg. Chem. 2000, 39, 3890.

Cationic Ge(II)-Transition Metal Complexes
Organometallics, Vol. 24, No. 12, 2005 2991
of that in [(8-MeO)Np]2(H)Ge(IV)OTf], where the ger-
manium is weakly linked to the triflate anion (1.99 Å).11
This distance is significantly longer than a covalent
Ge-O bond (1.75-1.85 Å)12 and appreciably shorter
than the sum of the van der Waals radii (3.66 Å).13 The
short Ge-W and the long Ge-O distances may be
rationalized as resulting from the tetracoordination of
the germanium, combined with dπ-σ* (GeO) π-donation
from the tungsten to the L2(TfO)Ge germanium ligand
(Ge-W multiple-bond character), which is favored by
the high electronegativity of the triflate group. Accord-
ingly, the L2(TfO)Ge moiety is seen by W(CO)5 as a
strong σ-donor with weak π-acceptor capacity, but
nevertheless superior to that postulated for the L2(X)-
Ge ligands in other known base-stabilized germylene-
pentacarbonyl complexes L2(X)GeW(CO)5.2j
To confirm the overall bonding situation of the triflate
ligand in compound 2 as derived from the X-ray results,
we have performed DFT (B3LYP) theoretical calcula-
tions of geometrical parameters for the neutral and
cationic model compounds 1′, 2′, and 2′′, respectively
(see Supporting Information).
Figure 2. Calculated energies of the frontier molecular
orbitals in 2′ and their Molekel visualization.
The calculated geometrical parameters for 1′ are in
good qualitative agreement with the available experi-
mental data for the dihalogermanium(II)-tungsten
complex 1.2j As expected, they show that the Ge-N and
Ge-W bond lengths shorten and the N1GeN2, N1GeW,
and N2GeW bond angles widen on going from the
neutral molecule 1′ to the cationic species 2′ and the
neutral 2′′, but less strongly for the latter one. For 2′
(optimized with C2v symmetry), the germanium atom
is sp2 hybridized and the Ge-W bond length is predicted
to be only 0.1 Å shorter than that calculated for 1′ and
2′′. It is noteworthy that the calculated structure of 2′
matches the experimental X-ray data for 2 very closely;
for example, the experimental Ge-N1 and Ge-W dis-
tances in 2 are 1.891 and 2.547 Å, respectively, while
those calculated for 2′ are 1.901 and 2.538 Å, respec-
tively. The experimental and calculated values of the
various bond angles also agree well, the experimental
values for 2 being closer to those calculated for the
cation 2′ than for the neutral molecules 1′ or 2′′.
Considering the total natural charges provided by the
NBO calculations (see Supporting Information), the
negative charges on tungsten, the two nitrogen atoms,
and the C8 carbon atom are modified as a result of the
increase of the positive charge on germanium in 2′
compared with 1′. This positive charge is stronger in
2′′ mainly due to the more pronounced withdrawing
effect of the OTf substituent. In the cationic molecule
2′, the negative charge on the C8 atom is smaller than
in the neutral compounds 1′ and 2′′, which is in
agreement with the deshielding observed in the 13C and
1H NMR spectra of 2 compared with those of 1. As
postulated from the X-ray results, the theoretical trends
are indicative of a triflate anion that is very weakly
bound to the germanium atom and weak π-back-
donation of tungsten to germanium.
the previously studied germanium cation [Ge(NHCH)2-
CH]+ 3i and examine the effect of tungsten complexation
on the nature and ordering of the molecular energy
levels. The energies of the frontier orbitals in 2′ and
their Molekel visualization are shown in Figure 2.
The LUMO is associated with the C-N π*-orbital and
lies only 3.69 kcal/mol lower than LUMO+1, which is
localized mainly on the Ge 4p-orbital. Thus, complex-
ation of [Ge(NHCMe)2CH]+ to tungsten restores the
unoccupied molecular orbital ordering observed for low-
valent Al and Ga analogues.3i However, these results
have to be taken with caution because of the consider-
able influence of the choice of basis set on the energies
and nature of unoccupied MOs. The three highest
occupied molecular orbitals (HOMO, HOMO-1, and
HOMO-2) correspond to the a2, b2, and b1 molecular
orbitals of the carbonyl groups, while the lower energy
orbitals HOMO-3 to HOMO-7 correspond to HOMO-
HOMO-4 in [Ge(NHCH)2CH]+.3i In 2′ HOMO-3 cor-
responds to the antibonding interaction between the
bonding combination of the π nitrogen lone pairs delo-
calized in the Ge 4p-orbital and the C-C π-bond, while
the strongly stabilized HOMO-4 (antibonding with
respect to the Ge-N bond, ∆(HOMO-3 - HOMO-4)
) 37.8 kcal) is associated mainly with the germanium
lone pair coordinated to tungsten. It is noteworthy that
the energy gap between the two corresponding orbitals
in [Ge(NHCMe)2CH]+ (HOMO and HOMO-1 calculated
with B3LYP/SDD) is only 22.75 kcal/mol. These results
provide strong evidence for Lewis base behavior of the
germanium lone pair in these complexes.
1.2. Reactions of L2(Cl)GeW(CO)5 with GaCl3,
NaBPh4, and AgPF6. Given the indication from the
preceding results of some degree of ion pairing in the
triflate complex 2, we decided to attempt to abstract the
chloride ions in 1 and 4 with MX3 (M ) Ga, X ) Cl; M
) In, X ) I), NaBPh4, or AgPF6. Disappointingly,
however, all these attempts were unsuccessful.
It is also of interest to look at the electronic structure
of the cationic tungsten complex 2′ in comparison with
(11) Cosledan, F.; Castel, A.; Rivie`re, P.; Satge´, J. Organometallics
1998, 17, 2222.
(12) Baines, K. M.; Stibbs, W. G. Coord. Chem. Rev. 1995, 145, 157.
(13) Chauvin, R. J. Phys. Chem. 1992, 96, 9194.
The reactions of 4 with MX3 in dichloromethane
afforded mainly the neutral gallium and indium com-

2992 Organometallics, Vol. 24, No. 12, 2005
Saur et al.
Scheme 4
Table 2. Crystallographic Data for 8
pounds L2MX2 (7 and 8) resulting from ligand transfer
reactions14 (Scheme 4).
empirical formula
C17H17I2InN2
fw
617.95
Compound 7 has been fully characterized by MS and
1H, 13C, and 71Ga NMR spectroscopies. The 71Ga NMR
spectrum of 7 (CDCl3, [Ga(H2O)6]3+: δ ) 246 ppm) is
in good agreement with the chemical shift observed for
the analogous tetracoordinate vinamidin gallium com-
plex.15 Hence the reactions of the germanium-tungsten
complex 1 with MX3 have not been studied for fear of
obtaining similar ligand-halogen exchange reactions.
Compound 8 was isolated as a yellow powder by
evaporation of a CH2Cl2 solution of 8 under reduced
pressure. Crystals of 8 were obtained by crystallization
from toluene at room temperature, and the structure
of 8 was determined crystallographically. The molecular
structure of 8 is shown in Figure 3; selected bond
lengths and angles are given in Table 2.
The structure consists of discrete monomeric molec-
ular units with a distorted tetrahedral geometry at In.
The L2 ligand is coordinated in an approximately
symmetrical fashion. The InNCCCN fragment is almost
planar, the indium and carbon C(2) distances from the
N(1)C(1)C(3)N(2) plane being 0.286 and 0.137 Å, re-
spectively; the sum of the angles at each nitrogen atom
is close to 360°. The In-N distances (2.11, 2.12 Å) are
in the range normally observed for In-N bonds in
tetracoordinate indium complexes incorporating N,N′-
bidentate monoanionic ligands16 and, as expected, are
slightly shorter than those in pentacoordinated indium
complexes containing two N,N′-bidentate ligands17 and
considerably shorter than the In-N distances (average
2.49 Å) in Lewis acid-base adducts.18 The In-I dis-
tances (2.67, 2.69 Å) are in the normal range for
tricoordinate or tetracoordinate indium compounds.16b,19
The structural features are quite similar to those
recently reported for the sterically encumbered iodide
cryst syst
space group
unit cell dimens
a (Å)
monoclinic
P21/c
13.924(1)
9.798 (1)
14.103(1)
2
b (Å)
c (Å)
â (deg)
V (Å3)
1919.7(2)
4
Z
Dcalc (Mg m-3
)
2.138
no. of reflns collected
no. of indep reflns
no. of params
10 920
3883
201
R1 [I > 2σ(I)]
0.0217
0.0557
0.934 and -0.798
wR2 [all data]
largest diff peak and hole (e‚Å-3
)
indium derivatives Dipp2nacnacInI2;16b the most notice-
able differences are in the N(1)-In-N(2) and I(1)-In-
I(2) angles, which are wider in 8, and in the C(3)N(2)
ring, which is closer to planar in 8. The 1H and 13C NMR
spectra are very similar to those of 7, indicating that
the methyl and phenyl groups are equivalent, probably
as a result of a fluxional process in solution.
The reaction of 1 with NaBPh4 in dichloromethane
resulted in a mixture of the novel germanium(II)
tungsten complexes L2(Ph)GeW(CO)5 (9) and L2(Ph2-
BO)GeW(CO)5 (10). These results are rationalized in
Scheme 5.
The cationic species [L2Ge+W(CO)5] is likely formed
first and then reacts by competing phenyl group transfer
from BPh4- to the germanium center (leading to 9; (a))
and hydrolysis to form complex 10 (b). This rationale is
supported by the fact that, in boron chemistry, phenyl
group transfers from BPh4 to metal20,21 and even
-
germanium3h centers are extremely common, as are
protodeboronation reactions (cleavage of a B-C bond
by a protic reagent).21 However, the exact mechanism
for the formation of 10 is uncertain since we cannot
exclude the possibility of initial hydrolysis of the boron
compound NaBPh4 to afford Ph2B(OH), which may then
react directly with L2(Cl)GeW(CO)5.
(14) Agustin, D.; Rima, G.; Gornitzka, H.; Barrau, J. Organometal-
lics 2000, 19, 4276.
(15) Kuhn, N.; Fahl, J.; Fadis, S.; Steimann, M.; Henkel, G.; Maulitz,
A. H. Z. Anorg. All. Chem. 1999, 625, 2108.
(16) (a) Delpech, F.; Guzei, I. A.; Jordan, R. F. Organometallics 2002,
21, 1167. (b) Stender, M.; Eichler, B. E.; Hardman, N. J.; Power, P. P.;
Prust, J.; Noltemeyer, M.; Roesky, H. W. Inorg. Chem. 2001, 40, 2794.
(17) Dias, H. V. R.; Jin, W. Inorg. Chem. 1996, 35, 6546.
(18) (a) Cowley, A. H.; Gabbai, F. P.; Isom, H. S.; Decken, A.; Culp,
R. D. Main Group Chem. 1995, 1, 9. (b) Schumann, H.; Go¨rlitz, F. H.;
Suub, T. D.; Wassermann, W. Chem. Ber. 1992, 125, 3. (c) Ku¨mmel,
C.; Meller, A.; Noltemeyer, M. Z. Naturforsch 1996, 51b, 209.
(19) (a) Meller, A.; Ku¨mmel, C.; Noltemeyer, M. Z. Naturforsch 1996,
51b, 107. (b) Godfrey, S. M.; Kelly, K. J.; Kramkowski, P.; McAuliffe,
C. A.; Pritchard, R. G. Chem. Comm. 1997, 1001.
Figure 3. Solid-state structure of L2(I)2In (8) (ellipsoids
are drawn at the 50% probability level). Hydrogen atoms
are omitted for clarity. Selected bond lengths (Å) and bond
angles (deg): In-I(1) 2.6723(3), In-I(2) 2.6861(3), In-N(1)
2.119(2), In-N(2) 2.113(2), N(2)-C(3) 1.340(4), C(2)-C(3)
1.396(4), C(2)-C(1) 1.403(4), N(1)-C(1) 1.343(4), N(1)-In-
N(2) 93.34(9), N(1)-In-I(1) 113.84(7), N(1)-In-I(2) 114.45-
(7), N(2)-In-I(1) 111.31(7), N(2)-In-I(2) 108.95(7).
(20) Strauss, S. H. Chem. Rev. 1993, 93, 927, and references therein.
(21) Odon, J. D. Non-cyclic Three and Four Coordinated Boron
Compounds. In Comprehensive Organometallic Chemistry, Wilkinson,
Stone, F. G. A., Abu, E. W., Eds.; Pergamon Press: Oxford, 1982; p 1.

Cationic Ge(II)-Transition Metal Complexes
Organometallics, Vol. 24, No. 12, 2005 2993
pound (1).2j The chemical shifts of the signals corre-
sponding to the methine and methyl protons appear at
higher field compared to the corresponding resonances
in 1 (CDCl3, δCH ) 5.38 (13), 5.56 (1); δCH3 ) 1.88 (13),
2.02 (1) ppm).2j The 13C spectrum shows the character-
istic chemical shifts of the carbon atom of the â-diketim-
inate ligand, shifted slightly upfield from those in the
spectrum of 1 (CDCl3, δCH ) 101.11 (13), 101.58 (1); δCH3
) 24.81 (13), 24.60 (1) ppm). Only one carbonyl reso-
nance is observed (CDCl3 δCO ) 200.96 ppm), indicative
of D4h symmetry at the tungsten atom (trans geometry).
In the carbonyl region of the IR spectrum, only one
strong band, characteristic of D4h symmetry at the
tungsten, is observed; this band appears at significantly
lower frequencies (νCO ) 1898 cm-1) than the corre-
sponding bands for L2(Cl)GeW(CO)5 (νCO ) 2072, 1984,
1943 cm-1).2j
Scheme 5
It is interesting to note that formation of cis-[L2(Cl)-
Ge]2W(CO)4 was not observed, contrary to what has
been reported in the cases of [(salen)Sn]2W(CO)4 (salen
) 2,2′-N,N′-bis(salicylidene)ethylenediamine)2h and
(carbene)2W(CO)4 complexes.22
The structure of 13 was unambiguously established
by single-crystal X-ray diffraction. Compound 13 is the
first digermanium(II)-tungsten complex to be structur-
ally characterized. Suitable crystals of 13 were obtained
in chloroform at room temperature. The molecular
structure of 13 is depicted in Figure 4, while the
crystallographic data are reported in Table 1.
The reactivity of AgPF6 with 1 was also examined in
a final attempted metathetisis reaction. This resulted
in a complicated mixture of products, of which the
hydrolysis products L2H+PF6 (11) and L2GeOP(O)F2
-
(12) were the only compounds that we were able to
identify.
2. Attempted Synthesis of L2Ge+[W(CO)4]Ge+L2.
2.1. [L2(Cl)Ge]2W(CO)4. As for the monocation L2-
Ge+W(CO)5, we sought to obtain the dication species [L2-
Ge+]2W(CO)4 by a similar synthetic approach, namely,
abstraction of the halide X- ligand from the trinuclear
bis(germanium(II))-tungsten complex L2(X)GeW(CO)4-
Ge(X)L2. To investigate these reactions, we first syn-
thesized the chloride disubstituted tungsten complex
[L2(Cl)Ge]2W(CO)4 (13) by irradiation of a mixture of 2
equiv of L2(Cl)Ge and 1 equiv of W(CO)6 in THF
(Scheme 6, method a). Compound 13 was also obtained
in 35% yield by direct irradiation of L2(Cl)GeW(CO)5 in
THF (Scheme 6, method b).
The molecular structure confirms the monomeric
nature of 13 and the trans orientation of the two L2-
(Cl)Ge fragments. Compound 13 is achiral, with the
inversion center located at the tungsten atom. In each
L2(Cl)Ge moiety of the trinuclear complex 13 the
germanium adopts a distorted tetrahedral geometry; the
geometry around the tungsten is nearly octahedral. The
N(1)-Ge-N(2) angles observed in the two L2(Cl)Ge
fragments (93.11°) are slightly smaller than those
observed in L2(Cl)GeW(CO)5 (93.90°).2j The Ge-W bond
distances (2.51 Å) are shorter than those observed in
the corresponding monosubstituted L2(X)GeW(CO)5 com-
plexes (X ) Cl, I: 2.57 Å; X ) OTf: 2.55 Å), indicating
that the strength of the interaction between the tung-
sten and the germanium atom is slightly influenced by
the number of ligands on the transition metal. The
Ge-N (1.93, 1.94 Å) and Ge-Cl (2.29 Å) bond lengths
are in the same range as those in the L2(Cl)GeW(CO)5
complex (Ge-N: 1.92, 1.93 Å; Ge-Cl: 2.26 Å). The
W-Ccis (2.02-2.03 Å) and the C-Ocis (1.15, 1.15 Å) bond
Complex 13 is a yellow solid insoluble in pentane and
1
slightly soluble (less than 1) in polar solvents. The H
and 13C NMR and IR spectra showed that the two L2-
(Cl)Ge fragments are equivalent and are thus consistent
1
with a trans structure (Table 1). The H and 13C NMR
spectra of complex 13 showed different chemical shifts
for the signals of the â-diiminate ligand relative to those
of the monosubstituted germanium(II)-tungsten com-
Scheme 6

2994 Organometallics, Vol. 24, No. 12, 2005
Saur et al.
Scheme 8
mono- and bis(substituted)germanium(II)-tungsten com-
plexes [L2(X)Ge]nW(CO)6-n. The metathesis reactions
investigated demonstrate that the classical “weakly
coordinating” anions TfO-, BPh4-, and PF6 are not
-
useful for the synthesis of such germanium cations. In
-
-
effect, while BPh4 and PF6 are not stable toward
germanium, the triflate was found to be weakly coor-
dinating to germanium in the solid state and in neutral
or polar solvents; interestingly, however, the weakness
of the interaction results in spontaneous dissociation of
the TfO- ligand in coordinating solvents, giving an
equilibrium mixture of neutral and ionic tetracoordi-
nated complexes (Scheme 8).
Further studies focusing on anions that are larger and
even more weakly coordinating than those investigated
in this work are currently in progress, keeping in mind
that as the anion becomes more weakly coordinating
and less nucleophilic, the halide complexes [L2(X)Ge]n-
W(CO)6-n will not be useful precursors to [L2Ge+]n-
W(CO)6-n cations. Consequently, the alkoxygermanium-
(II)tungsten complexes [L2(OR)Ge]nW(CO)6-n are being
investigated as precursors of these cations via their
reactions with boron compounds. In the course of this
work, several new stable mono- and trans-disubstituted
germanium(II)-tungsten carbonyl complexes have been
prepared and structurally characterized. The Ge-W
bond lengths observed in these complexes are among
the shortest that have been observed; this indicates that
the heteroleptic divalent species L2(X)Ge (X ) halide,
TfO-) in these complexes behave as σ-donors with weak
hyperconjugative π-acceptor character.
It is interesting to note a few analogies between the
P-W bonds in some phosphorus-tungsten complexes
and the Ge-W bonds studied in the present work.
Complexes of the type R3P‚W(CO)5 are tetracoordinate
phosphorus compounds, but physical and chemical
evidence suggests that in these compounds the P-W
bond is not a pure donor bond, but rather possesses
some double-bond character depending on the R group.
The molecular structures and carbonyl stretching fre-
quencies of the â-diketiminate germanium(II)- and the
related phosphine-tungsten complexes of general for-
mula L′nW(CO)6-n are compared in Table 3.
Figure 4. Solid-state structure of [L2(Cl)Ge]2W(CO)4 (13)
(ellipsoids are drawn at the 50% probability level). Selected
bond lengths (Å) and bond angles (deg): Ge-Cl ) 2.8880-
(10), Ge-N(1) 1.937(3), Ge-N(2) 1.930(3), Ge-W 2.5125-
(4), W-C(18) 2.016(4), W-C(18A) 2.016(4), W-C(19) 2.026-
(4), W-C(19A) 2.026(4), C(18)-O(1) 1.153(5), C(19)-O(2)
1.153(4), N(1)-Ge-N(2) 93.11(13), N(1)-Ge-Cl 95.41(9),
N(2)-Ge-Cl 93.41(9), N(1)-Ge-W 126.14(9), N(2)-Ge-W
125.57(9), Cl-Ge-W 115.15(3), Ge-W-C(18) 94.44(11),
Ge-W-C(18A) 85.56(11), Ge-W-C(19) 93.64(10), Ge-W-
C(19A) 86.36(10).
Scheme 7
lengths are also nearly identical to those in the di-
nuclear L2(X)GeW(CO)5 complexes (X ) Cl, I, OTf). As
postulated for the monosubstituted complexes L2(X)-
GeW(CO)5,2j these data are consistent with an unsatur-
ated character (hyperconjugative dw-σ*(GeCl, GeN),
dw-π* (CN)) of the Ge-W units and underline the
strong σ-donor and the weak π-acceptor (poorer than
CO) nature of the L2(Cl)Ge ligand toward tungsten.
2.2. Reactions of [L2(Cl)Ge]2W(CO)4 with AgOTf.
Complex 13 reacts with AgOTf in toluene at room
temperature to yield a yellow, air-sensitive solid (14)
that is insoluble in CHCl3, CH2Cl2, pentane, and
toluene, but is soluble in DMSO. The 1H NMR spectrum
of 14 in DMSO-d6 is similar to that of 2 in pyridine,
showing two signals for the methine and methyl groups
of the â-diketiminate ligand (δCH ) 5.57, 5.92; δCH3
)
Each of the five L′W(CO)5 and both L′2W(CO)4 com-
plexes are isostructural around tungsten. For each of
these complexes, the W-Ctrans distance is shorter than
the W-Ccis distance. These observations are in accord
with the notion that W-C π-bonding is more pro-
nounced for the W-CO bond trans to L′ when the latter
is a weaker π-acceptor than CO. Both the W-Ccis and
the W-Ctrans distances vary little with the nature of L′
in these complexes. Consequently, the π-acceptor char-
acter of the L2(X)Ge ligand in the complexes 1, 2, 6, and
13 seems comparable or slightly weaker than that of
the phosphine ligand in complexes 15-17. In addition
the CO stretching frequencies are closely similar in the
Ge(II)- and related P-W complexes. This suggests an
almost identical back-donation from the tungsten atom
2.03, 2.30 ppm). In addition, evidence for the presence
of ionic triflate is given by the IR spectrum in DMSO-
d6 solution, which reveals a strong ν(SO3) vibration
mode at 1271.4 cm-1 characteristic of ionic triflate and
a weak vibration at 1370.5 cm-1 corresponding to
covalently bound triflate (Scheme 7).
Conclusion
As a general approach to the synthesis of highly
reactive cationic germanium species, we have carried
out a study of halide abstraction reactions from the
(22) Hitchcock, P. B.; Lappert, M. F.; Pye, P. J. Chem. Soc., Dalton
Trans. 1977, 2160.

Cationic Ge(II)-Transition Metal Complexes
Organometallics, Vol. 24, No. 12, 2005 2995
Table 3. Average Bond Distances (in Å) and IR (νCO in cm-1) for L′nW(CO)6-n Complexes
L′nW(CO)6-n
W-Ea
W-Ctrans
W-Ccis
IR
Ph3PW(CO)5
1523a,b
1623b,c
1
2.545(1)
2.378(4)
2.567(1)
2.571(1)
2.547(1)
2.513(1)
2.479(1)
2.006(5)
2.020(20)
1.995(5)
1.978(8)
1.995(5)
2.033(5)
2.033(12)
2.038(1)
2.036(1)
2.040(4)
2.021(4)
2.041(1)
2072, 1980, 1942b
2094, 1994, 1980c
2072, 1984, 1943d
2071, 1984, 1945e
2062, 1974,1932d
1898d
Cl3PW(CO)5
L2(Cl)GeW(CO)5
L2(I)GeW(CO)5
L2(TfO)GeW(CO)5
[L2(Cl)Ge]2W(CO)4
(Ph3P)2W(CO)4
6
2
13
1724
1886f
a E ) P or Ge. b Cyclohexane. c Cyclopentane. d Chloroform. e Tetrahydrofuran. f Dichloromethane.
Huzinaga valence double-ú basis set for the first-row atoms28
and the Stuggart/Dresden29 effective core potential basis set
for the others. Geometry optimizations were followed by
frequency calculations in order to verify that the stationary
points obtained are true minima. For NBO calculations and
Molekel visualizations, see refs 30 and 31, respectively.
Synthesis of L2(OTf)GeW(CO)5 (2). (a) A tetrahydrofuran
solution (60 mL) of W(CO)6 (510 mg, 1.45 mmol) was irradiated
for 2 h. CO was eliminated by bubbling of argon in the reaction
mixture for 15 min, and then a tetrahydrofuran solution (30
mL) of L2(OTf)Ge (684 mg, 1.45 mmol) was slowly added at
room temperature. The mixture was stirred for 2 h. The
volatile materials were removed under reduced pressure to
obtain 2 as a yellow solid (75% yield, 863 mg). (b) A toluene
solution (15 mL) of L2(Cl)GeW(CO)5 (80 mg, 0.12 mmol) was
added to a suspension of AgOTf (30 mg, 0.12 mmol) in toluene
(10 mL). The reaction mixture was then stirred at room
temperature in the absence of light for 1 h and filtered. The
volatile materials were removed under reduced pressure to
yield 2 as a yellow solid (80% yield, 76 mg). Crystallization
from toluene at -30 °C gave yellow crystals of 2. Mp: 119-
123 °C (dec). IR: (CHCl3) ν 2062.4, 1973.9, 1932.3 (CO), 1366.5
(OTf); (C6D6) ν 2079.3, 1986.2, 1943.1 (CO), 1365.4 (OTf);
(C5H5N) ν 2063.8, 1934.4, 1920.5 (CO), 1379.1, 1274.0 (OTf)
to the carbonyl ligands in these complexes, consistent
with the view that the L2(X)Ge and R3P phosphine
ligands possess weak and nearly identical π-acceptor
capacities.
Experimental Section
General Procedures and Materials. All manipulations
were carried out under an argon atmosphere with the use of
standard Schlenk and high-vacuum-line techniques. Solvents
were distilled from conventional drying agents and degassed
twice prior to use.25 L2(Cl)Ge (4) and L2(Cl)GeW(CO)5 (1) were
prepared according to the previously reported methods.2j,5a 1
H
NMR spectra were recorded on a Bru¨ker AC 80 spectrometer
operating at 80.13 MHz (chemical shifts are given in ppm (δ)
relative to Me4Si) and 13C spectra on a AC-250 spectrometer
operating at 62.9 MHz. 19F{1H} and 31P{1H} NMR spectra were
recorded on a Bru¨ker AC-200 spectrometer operating at 188.3
and 81.02 MHz, respectively. 71Ga{1H} NMR spectra were
recorded on a Bru¨ker AC 300 WB spectrometer operating at
91.531 MHz; chemical shifts are given in ppm (δ) relative to
[Ga(H2O)6]3+. Mass spectra were recorded on a Nermag R10-
10H or a Hewlett-Packard 5989 instrument operating in the
electron impact mode at 70 eV, and samples were contained
in glass capillaries under argon. IR spectra were obtained on
a Perkin-Elmer 1600 FT-IR spectrometer. Irradiations were
carried out at 25 °C using a low-pressure mercury immersion
lamp in a quartz tube. Melting points were measured on a hot-
plate microscope apparatus from Leitz Biomed. Elemental
analyses (C, H, N) were performed by the Microanalysis
Laboratory of the Ecole Nationale Supe´rieure de Chimie de
Toulouse.
1
cm-1. H NMR (C6D6): δ 1.58 (s, 6H, CH3), 5.24 (s, 1H, CH),
6.93-7.29 (m, 10H, C6H5). 1H NMR (CDCl3): δ 2.11 (s, 6H,
CH3), 5.85 (s, 1H, CH), 7.19-7.51 (m, 10H, C6H5). 1H NMR
(C5D5N): δ 1.77 (s, 6H, CH3), 2.11 (s, 6H, 2CH3), 5.12 (s, 1H,
CH), 5.32 (s, 1H, CH), 7.20-7.55 (m, 20H, C6H5). 13C NMR
(C6D6): δ 24.02 (s, CH3), 103.83 (s, CH), 121.4 (s, CF3), 127.57
(s, m-aryl-C), 128.13 (s, p-aryl-C), 129.09 (s, o-aryl-C), 141.54
(s, Cipso), 169.53 (s, C-N), 194.64 (s, CO), 197.41 (s, CO). 19F
NMR (C6D6): δ -1.65 (s, CF3). MS: m/z 794 [M]+•, 766 [M -
CO]+•, 645 [M - OTf]+. Anal. Calcd for C23F3GeH17N2O8SW
(794.95): C, 34.75; H, 2.16; N, 3.52. Found: C, 34.68; H, 2.08;
N, 3.47.
Theoretical calculations were performed with the Gaussian
98 program.26 The density functional theory was used with
the hybrid exchange functional B3LYP.27 Calculations were
realized with the SDD basis set, which adopts the Dunning/
Synthesis of L2(OTf)Ge (3). A toluene solution (10 mL)
of L2GeCl (189 mg, 0.53 mmol) was slowly added to a
suspension of AgOTf (136 mg, 0.53 mmol) in toluene (10 mL).
The reaction mixture was then stirred at room temperature
in the absence of light for 1 h and filtered. The volatile
materials were removed under reduced pressure to yield 3 as
a yellow solid (75% yield, 188 mg). Mp: 146-155 °C (dec). IR:
(CHCl3) ν 1378.7 (OTf); (C6D6) ν 1367.7 (OTf); (C5H5N) ν
1367.4, 1271.7 (OTf) cm-1. 1H NMR (C6D6): δ 1.44 (s, 6H, CH3),
4.98 (s, 1H, CH), 6.95-7.42 (m, 10H, C6H5). 1H NMR (CDCl3):
δ 2.07 (s, 6H, CH3), 5.66 (s, 1H, CH), 7.33-7.39 (m, 10H,
C6H5). 13C NMR (C6D6): δ 23.88 (s, CH3), 103.45 (s, CH), 119.8
(s, CF3), 129.49 (s, m-aryl-C), 129.96 (s, p-aryl-C), 131.02 (s,
o-aryl-C), 142.44 (s, Cipso), 168.82 (s, C-N). 19F NMR (C6D6):
δ -2.03 (s, CF3). MS: m/z 472 [M]+•, 323 [M - OTf]+. Anal.
(23) (a) Bancroft, G. M.; Dignard-Bailey, L.; Puddephatt, R. J. Inorg.
Chem. 1986, 25, 3675. (b) Aroney, M. J.; Buys, I. E.; Davies, M. S.;
Hambley, T. W. J. Chem. Soc., Daltons. Trans. 1994, 2827. (c) Davies,
M. S.; Pierens, R. K.; Aroney, M. J. J. Organomet. Chem. 1993, 458,
141.
(24) Hirsivaana, L.; Haukka, M.; Pursiainen, J. Inorg. Chem.
Commun. 2000, 3, 508.
(25) Perrin, D. D.; Armarego, D. R. Purification of Laboratory
Chemicals; Pergamon Press: New York, 1985.
(26) Frisch, M. J.; Trucks, G. W.; Schlegel, H. B.; Scuseria, G. E.;
Robb, M. A.; Cheeseman, J. R.; Zakrewski, V. G.; Montgomery, J. A.;
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2996 Organometallics, Vol. 24, No. 12, 2005
Saur et al.
1
Calcd for C18F3H17N2O3SGe (470.996): C, 45.90; H, 3.64; N,
5.95. Found: C, 45.95; H, 3.70; N, 5.92.
12: L2GeOP(O)F2. 31P NMR (CD3CN): -22.1 (t, JPF ) 978
Hz). 19F NMR (CD3CN): δ -0.54 (d, 1JFP ) 979 Hz). 1H NMR
(CD3CN): δ 2.01 (s, 6H, CH3), 5.63 (s, 1H, CH), 7.04-7.46 (m,
Synthesis of L2Ga(Cl)2 (7). A dichloromethane solution
(5 mL) of L2GeCl (4) (421 mg, 1.17 mmol) was added to a
suspension of GaCl3 (206 mg, 1.18 mmol) in dichloromethane
(5 mL) at -78 °C. The reaction mixture was warmed to room
temperature for 2 h. After filtration and removal of the solvent
under reduced pressure, 7 was obtained as a yellow solid (50%
yield, 228 mg). Mp: 165-170 °C (dec). 1H NMR (CDCl3): δ
1.92 (s, 6H, CH3), 5.10 (s, 1H, CH), 7.12-7.42 (m, 10H, C6H5).
13C NMR (CDCl3): δ 23.66 (s, CH3), 97.19 (s, CH), 126.26 (s,
m-aryl-C), 127.21 (s, p-aryl-C), 129.47 (s, o-aryl-C), 142.93 (s,
10H, C6H5). MS: m/z 424 [M]+•
.
Synthesis of [L2(Cl)Ge]2W(CO)4 (13). (a) A mixture of L2-
GeCl (4) (998 mg, 2.79 mmol) and W(CO)6 (490 mg, 1.40 mmol)
in tetrahydrofuran (60 mL) was irradiated for 4 h. CO was
eliminated by bubbling of argon in the reaction mixture for
15 min. The volatile materials were removed under reduced
pressure; subsequent addition of pentane and filtration af-
forded crude 13 as a yellow solid (70% yield, 992 mg).
Recrystallization from chloroform at room temperature gave
yellow crystals of 13.
C
ipso), 170.09 (s, C-N). 71Ga NMR (CDCl3): δ 245.8. MS: (EI)
m/z 390 [M]+•. Anal. Calcd for C17H17N2GaCl2 (389.95): C,
52.36; H, 4.39; N, 7.19. Found: C, 52.26; H, 4.40; N, 7.25.
Synthesis of L2In(I)2 (8). A dichloromethane solution (8
mL) of L2GeCl (4) (352 mg, 0.98 mmol) was added to a
suspension of InI3 (486 mg, 0.98 mmol) in dichloromethane (8
mL) at -78 °C. The reaction mixture was warmed to room
temperature for 2 h. After filtration and removal of the solvent
under reduced pressure, 8 was obtained as a yellow solid (52%
yield, 315 mg). Crystallization from toluene at room temper-
ature gave yellow crystals of 8. Mp: 136-138 °C (dec). 1H NMR
(C6D6): δ 1.48 (s, 6H, CH3), 4.55 (s, 1H, CH), 7.03-7.11 (m,
10H, C6H5). 13C NMR (C6D6): δ 24.03 (s, CH3), 97.62 (s, CH),
125.44 (s, m-aryl-C), 126.06 (s, p-aryl-C), 129.64 (s, o-aryl-C),
146.02 (s, Cipso), 169.56 (s, C-N). MS: m/z 618, [M]+•, 491 [M
- I]+. Anal. Calcd for C17H17N2InI2 (617.926): C, 33.04; H, 2.77;
N, 4.53. Found: C, 32.97; H, 2.65; N, 4.51.
(b) A C6D6 solution (2 mL) of L2(Cl)GeW(CO)5 (1) (50 mg,
0.07 mmol) was irradiated for 3 h. The solution turned maroon,
and a black solid appeared. After filtration, the solution was
determined to be a mixture of 1 (65%) and 13 (35%).
13: Mp: 190-205 °C (dec). IR (CHCl3): ν 1897.8 cm-1 (CO).
1H NMR (CDCl3): δ 1.88 (s, 12H, CH3), 5.38 (s, 2H, CH), 7.22-
7.42 (m, 20H, C6H5). 1H NMR (C6D6): δ 1.45 (s, 12H, CH3),
4.96 (s, 2H, CH), 7.20-7.48 (m, 20H, C6H5). 13C NMR
(CDCl3): δ 24.81 (s, CH3), 101.11 (s, CH), 127.73 (s, m-aryl-
C), 129.49 (s, p-aryl-C), 129.72 (s, o-aryl-C), 143.18 (s, Cipso),
166.82 (s, C-N), 200.96 (s, CO). MS: m/z 358 [M - L2Ge(Cl)
- W(CO)4]+•. Anal. Calcd for C38H34N4O4Cl2Ge2W (1010.62):
C, 45.16; H, 3.39; N, 5.54. Found: C, 45.20; H, 3.42; N, 5.62.
Reaction of [L2(Cl)Ge]2W(CO)4 with AgOTf. A toluene
suspension (10 mL) of (L2(Cl)Ge)2W(CO)4 (13) (177 mg, 0.18
mmol) was added to a suspension of AgOTf (93 mg, 0.36 mmol)
in toluene (10 mL). The reaction mixture was then stirred at
room temperature for 1 h and filtered. The brown precipitate
was dissolved in DMSO (AgCl precipitate), and the solution
was analyzed by 1H NMR and IR spectroscopy (52% yield, 116
mg). IR: (d6-DMSO) ν 1271.4 (OTf), 1370.5 (OTf), 1904.4 (CO)
Reaction of L2(Cl)GeW(CO)5 (1) with NaBPh4. A dichlo-
romethane solution (10 mL) of L2(Cl)GeW(CO)5 (257 mg, 0.377
mmol) was added to a suspension of NaB(Ph)4 (129 mg, 0.377
mmol) in dichloromethane (5 mL) at room temperature. The
reaction mixture was refluxed during 1 day and then filtered.
The volatile materials were removed under reduced pressure
to obtain a yellow solid (290 mg). The 1H NMR and mass
spectra of the crude product showed the presence of 9 and 10
cm-1. H NMR (d6-DMSO): δ 2.03 (s, 6H, CH3), 2.30 (s, 6H,
1
CH3), 5.57 (s, 1H, CH), 5.92 (s, 1H, CH), 7.07-7.50 (m, 20H,
C6H5). MS: (EI) m/z 472 [M - L2Ge(OTf)W(CO)4]+•
.
1
in addition to minor unidentified products. H NMR and MS
X-ray Crystal Structure Determination of Compounds
2, 8, and 13. Crystal data for 2, 8, and 13 are presented in
Table 1. All data were collected at low temperatures (-80 °C)
on a Bru¨ker-AXS CCD 1000 diffractometer with Mo KR
radiation (λ ) 0.71073 Å). The structures were solved by direct
methods by means of SHELXS-9732 and refined with all data
on F2 by means of SHELXL-97.33 All non-hydrogen atoms were
refined anisotropically. The hydrogen atoms of the molecules
were geometrically idealized and refined using a riding model.
data for 9 and 10 were extracted from spectra of the mixture.
9: L2(Ph)GeW(CO)5. 1H NMR (CDCl3): δ 1.98 (s, 6H, CH3),
5.30 (s, 1H, CH), 7.18-7.69 (m, 15H, C6H5). MS: m/z 722 [M]+•,
694 [M - CO]+•, 638 [M - 3CO]+•, 582 [M - 5CO]+•
.
10: L2(B(Ph)2O)GeW(CO)5. 1H NMR (CDCl3): δ 1.99 (s, 6H,
CH3), 5.31 (s, 1H, CH), 7.20-7.76 (m, 20H, C6H5). MS: m/z
826 [M]+•, 742 [M - 3CO]+•, 686 [M - 5CO]+•
.
Reaction of L2(Cl)GeW(CO)5 (1) with AgPF6. A dichlo-
romethane solution (10 mL) of L2(Cl)GeW(CO)5 (1) (350 mg,
0.513 mmol) was added to a suspension of AgPF6 (130 mg,
0.513 mmol) in dichloromethane (5 mL) at room temperature
and in the absence of light. The reaction mixture was stirred
for 1 h at room temperature and then filtered. 11 crystallized
as yellow needles after the solution stood at room temperature
for 2 days. The volatile materials in the remaining solution
were removed under reduced pressure to yield a yellow solid
Acknowledgment. A.C. and V.L. acknowledge the
Conseil Re´gional d’Aquitaine for financial support for
V.L.
Supporting Information Available: CIF files for the
structures reported in this paper. 1H, 13C{1H}, and 19F{1H}
NMR (C6D6) and IR data for compounds 2, 3, and 13. Cartesian
coordinates and total natural charge of compounds 1′, 2′, and
2′′. This material is available free of charge via the Internet
at http://pubs.acs.org.
1
crude product (180 mg), the H, 19F, and 31P NMR and mass
spectra of which indicated it to consist of ca. 2:3 molar mixture
of 11 and 12 in addition to minor unidentified products.
1
11: (L2H2)+(PF6)-. 31P NMR (CD3CN): 143.6 (hept, JPF
)
OM050214V
707 Hz). 19F NMR (CD3CN): δ 7.81 (d, 1JFP ) 707 Hz). 1H NMR
(80.13 MHz, CD3CN): δ 2.54 (s, 6H, CH3), 5.54 (s, 1H, CH),
7.07-7.49 (m, 10H, C6H5), 8.93 (s, 2H, NH).
(32) Sheldrick, G. M. Acta Crystallogr. Sect. A 1990, 46, 467.
(33) Sheldrick, G. M. SHELXL-97, Program for Crystal Structure
Refinement; Universita¨t Go¨ttingen, 1997.