Reactivity of divalent germanium alkoxide complexes is in sharp contrast to the heavier tin and lead analogues

Article abstract of DOI:10.1021/ic201841m

The chemistry of β-diketiminate germanium alkoxide complexes has been examined and shown to be in sharp contrast to its heavier congeners. For instance, (BDI)GeOR (BDI = [{N(2,6-ⁱPr₂C₆H ₃)C(Me)}₂CH],

Full text of DOI:10.1021/ic201841m

Article
pubs.acs.org/IC
Reactivity of Divalent Germanium Alkoxide Complexes Is in Sharp
Contrast to the Heavier Tin and Lead Analogues
Lorenzo Ferro, Peter B. Hitchcock, Martyn P. Coles, and J. Robin Fulton*,†
Department of Chemistry, University of Sussex, Falmer, Brighton BN1 9Q J, United Kingdom
S
* Supporting Information
ABSTRACT: The chemistry of β-diketiminate germanium
alkoxide complexes has been examined and shown to be in
sharp contrast to its heavier congeners. For instance,
(BDI)GeOR (BDI = [{N(2,6-iPr2C6H3)C(Me)}2CH], R =
s
t
iPr, Bu, Bu) does not react with carbon dioxide to form a
metal carbonate complex. Addition of aliphatic electrophiles,
such as methyl iodide or methyl triflate, results in the net
oxidative addition to the germanium, giving cationic tetravalent
germanium complexes, [(BDI)Ge(Me)OR][X] (X = I, OTf).
An examination of the contrasting reactivities of the alkoxide
ligand and the germanium loan pair with Lewis acids yielded
the unusual germanium(II)−copper(I) adduct, {μ2-Cu2I2}-
[(BDI)GeOtBu]2. This complex not only displays a rare example of a divalent Ge−Cu bond, but is the first example in which a
planar Cu2I2 diamond core possesses a three-coordinate copper bound to another metal center.
INTRODUCTION
RESULTS AND DISCUSSION
■
■
Synthesis. Three β-diketiminate germanium alkoxides
We have recently synthesized a series of β-diketiminate divalent
lead- and tin-alkoxide complexes,1,2 as well as tin-amide
complexes,3 to gauge an understanding of their potential
nucleophilicities in comparison to their transition metal
counterparts. While these complexes were surprisingly non-
reactive with most aliphatic electrophiles, facile, but reversible,
insertion of carbon dioxide into the M−O bond of the
alkoxides was observed. This reactivity was attributed to the
nucleophilic interaction between the alkoxide oxygen atom and
the electropositive carbon in carbon dioxide, as well as an
electrostatic interaction between the metal center and one of
the oxygen atoms of carbon dioxide.2 It was discovered that the
strength of the metal−oxygen bond helped govern both the
initial reactivity as well as the reversibility of the carbon dioxide
insertion. For instance, the lead alkoxides, with weaker M−O
bonds, react much quicker and favor the insertion products
more than the isostructural tin systems.
We wished to expand this study to germanium alkoxide
complexes. Other β-diketiminate germanium complexes bear-
ing oxygen-based ligands have previously been synthesized,
including triflate complexes,4−6 heterobimetallic complexes in
which the metals are bridged by an oxo-ligand,5,7,8 a germanium
hydroxide complex and its complexes with iron and manganese
Lewis acids,9−11 as well as thionocarboxylate and selenocarbox-
ylate derivatives.12,13 In addition, the germylene ester of formic
acid was generated upon treatment of a germanium hydride
with carbon dioxide,14 and germanium phenoxides have also
been synthesized.15 However, outside of coordination chem-
istry, the reactivity between such complexes with electrophiles
has not been examined.
complexes, (BDI)GeOR (BDI = [{N(2,6-iPr2C6H3)C-
(Me)}2CH]¯), were synthesized by treatment of a THF
solution of (BDI)GeCl (1) with the appropriate potassium
alkoxide, affording germanium alkoxides (BDI)GeOiPr (2a),
(BDI)GeOsBu (2b), and (BDI)GeOtBu (2c) (eq 1). The H
1
and 13C NMR spectra are similar to the isostructual lead and tin
analogues.1,2 For instance, the 1H NMR spectrum of
isopropoxide 2a exhibits a singlet at δ 4.64 ppm, corresponding
to the ligand backbone γ-CH proton. Two sets of apparent
septets (δ 3.73 and 3.34 ppm) and four doublets (δ 1.51, 1.49,
1.17, and 1.10 ppm) are also observed, corresponding to the
aryl isopropyl groups. This pattern is consistent with a loss of
planar symmetry in the BDI-Ge metallocycle, which is due to
the trigonal pyramidal geometry of the three-coordinate Ge(II)
center.
Single crystals of these germanium alkoxide complexes, 2a−2c,
were grown overnight from saturated hexane solutions at −27 °C
Received: August 23, 2011
Published: January 13, 2012
© 2012 American Chemical Society
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(Figure 1). Selected bond lengths and angles are reported in
Table 1. Data collection parameters are listed in Table 2. These
aryloxides (BDI)GeOPh (1.860(4) Å) and (BDI)GeOC6F5
(1.95115(14) Å).15 In contrast, the Ge−N bond lengths of
alkoxides 2a−2c are longer, and the N1−Ge−N2 bond angle of
our alkoxides is more acute.
Reactivity Studies: Heterocumulenes. In sharp contrast
to the lead and tin analogues,1,2 no reaction is observed
between germanium alkoxides 2a and 2c and up to 1.5 atm of
carbon dioxide, even after heating to 50 °C. This result is
consistent with our proposed carbon dioxide insertion
mechanism that is dependent upon the M−O bond dissociation
energy, which increases going up the group. Similarly, addition
of maleic anhydride to germanium alkoxides 2a−2c did not
result in a reaction, even at elevated temperatures. Addition of
carbon disulfide to 2a−2c resulted in an intractable mixture of
products.
Addition of phenyl isocyanate to 2a did not result in a
reaction at room temperature. However, at 50 °C, partial
formation of a new compound (3a) was observed, with a ratio
1
of 2a to 3a of 58:42, as measured by H NMR spectroscopy.
A doublet at δ 7.01 ppm and two sets of triplets at δ 6.89 and
6.67 ppm were observed in a 2:2:1 ratio, consistent with a new
aromatic environment. A singlet was also observed at δ 5.03 ppm
and two sets of septets at δ 5.22 and 3.56 ppm in a 1:1:2
ratio, corresponding to the γ-CH, the OCHMe2, and the Ar−
CHMe2 protons, respectively. We have tentatively assigned 3a
to be the carbamate species shown in eq 2. The NMR spectral
Figure 1. ORTEP diagrams of (BDI)GeOiPr 2a (top left),
(BDI)GeOtBu 2c (top right), and (BDI)GeOsBu 2b (bottom middle)
with H atoms omitted (for 2a, 2b, and 2c) and BDI aryl group C
atoms minimized for clarity (for 2a and 2c); ellipsoid probability
shown at 30%.
Table 1. Selected Bond Lengths (Å) and Angles (deg) for
Compounds 2a, 2b, and 2c
(BDI)GeOiPr
(BDI)
(BDI)GeOtBu
a
(2a)
GeOsBu(2b)
(2c)
Ge−O
1.821(2)
2.020(2)
2.016(2)
1.432(4)
96.10(10)
94.63(10)
87.74(9)
117.0(2)
0.853
1.8294(12)
2.0244(14)
2.0234(14)
1.429(4)
96.70(6)
96.31(6)
87.48(5)
116.4(2)
0.804
1.8284(3)
2.0222(14)
2.0274(15)
1.437(7)
94.45(6)
96.00(6)
87.63(6)
120.9(4)
0.900
Ge−N(1)
Ge−N(2)
O−C(30)
a
data is similar to that of the isostructural lead carbamate
complex. Interestingly, increasing the temperature to 60 °C
resulted in a change in ratio of 2a to 3a of 64:36. Cooling to
room temperature changed the ratio in favor of 3a; however,
this increase was modest as the ratio of 2a to 3a was 53:47.
Addition of 5 equiv of phenyl isocyanate to 2a resulted in an
intractable mixture of products.
N(1)−Ge−O
N(2)−Ge−O
N(1)−Ge−N(2)
a
C(30) −O−Ge
b
Ge−NCCCNplane
sum of angles around
Ge
278.47
280.49
278.08
c
DP (%)
90.6
88.3
91.0
The germanium tert-butoxide complex 2c does not react with
phenyl isocyanate, even at elevated temperatures; whereas the
sec-butoxide complex 2b does, presumably forming 3b.
However, similar to the isopropoxide system, an equilibrium
is established between 2b and 3b, with a 76:24 2b:3b ratio
observed at 60 °C and a 66:34 ratio observed at 50 °C. Cooling
to room temperature changed the observed ratio to 59:41.
The low reactivity could be a function of the relatively strong
Ge−O bond, requiring a higher activation barrier to react.2
However, at elevated temperatures, the reactants are favored
over the products due to entropic factors playing more of an
importance over enthalpic ones. Unfortunately, attempts at
qualitatively measuring the equilibrium, as well as gaining
further spectroscopic characterization data of 3a and 3b, were
thwarted by the appearance of an insoluble white precipitate
after a few hours at elevated temperatures. In an attempt to
fully convert the alkoxides 2a to 2c to an isolable product, they
were treated with the more reactive PhNCS; however, no
reaction was observed at room temperature, and an intractable
mixture of products was observed at 50 °C.
a
b
C(31) for 2b. Distance between Ge and the plane defined by the
c
BDI-backbone (N−C−C−C−N plane). Degree of pyramidalization
(DP) = [(360 − sum of bond angles)/0.9].16
structures are isomorphous with both the lead and tin
analogues, and exhibit a pyramidal geometry around the
germanium center due to the presence of a 4s2 stereochemically
active lone pair. An “exo” conformation is observed, with the
alkoxide ligand pointing away from the (BDI)-metal core,3
presumably due to the inability of the bulky alkoxide group to
fit in-between the two aromatic rings of the BDI ligand. The
Ge−O bond length is longer for the bulkier tert-butoxide
complex 2c than the isopropoxide analogue, 2a.
Some general group 14 periodic trends can be observed from
these crystal structure data. For instance, the M−O and M−N
bond lengths increase with the radius of the metal center, and
the N−M−N and N−M−O angles decrease with the larger
metal centers, plausibly due to the increase in steric pressure
exerted by the more diffuse lone pair. The observed Ge−O
bond lengths of germanium alkoxides are shorter than Roesky’s
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Table 2. Crystallographic Data for Compound 2a, 2b, and 2c
a
b
LGeOiPr (2a)
LGeOsBu (2b)
C33H50GeN2O
LGeOtBu (2c)
C33H50GeN2O
chemical formula
fw
C32H48GeN2O
549.31
563.34
563.34
T (K)
173(2)
173(2)
173(2)
wavelength (Å)
cryst size (mm3)
cryst system
space group
a (Å)
0.710 73
0.710 73
0.710 73
0.25 × 0.20 × 0.15
monoclinic
P21/n (No.14)
13.1504(5)
16.3912(3)
15.2918(6)
90
0.21 × 0.16 × 0.12
triclinic
0.15 × 0.10 × 0.10
monoclinic
P21/c (No.14)
13.3507(3)
16.6088(3)
16.9602(3)
90
P1 (No.2)
̅
8.5920(1)
11.7494(3)
16.6858(4)
102.907(1)
102.097(2)
95.886(1)
1585.59(6)
2
b (Å)
c (Å)
α (deg)
β (deg)
107.328(1)
90
121.696 (1)
90
γ (deg)
V (Å3)
3146.56(18)
4
3199.82(11)
4
Z
−3
pc (Mg m )
1.16
1.18
1.17
−1
abs coeff (mm )
1.00
0.99
0.983
θ range for data collection (deg)
measured/indep reflns/R(int)
reflns with I >2σ(I)
3.48−26.15
18 604/61 27/0.056
4769
3.46−27.10
26 337/6947/0.050
6133
3.42−25.86
44 895/6043/0.061
5144
data/restraints/params
GOF on F2
6127/0/337
1.022
6947/22/401
1.023
6043/133/381
1.017
final R indices
R1 = 0.048, wR2 = 0.100
R1 = 0.069, wR2 = 0.111
0.54 and −0.82
R1 = 0.032, wR2 = 0.076
R1 = 0.040, wR2 = 0.080
0.39 and −0.40
R1 = 0.030, wR2 = 0.069
R1 = 0.040, wR2 = 0.072
0.32 and −0.35
R indices (all data)
largest diff. peak and hole (e Å3)
a
The sec-butyl group and one of the isopropyl groups are disordered and were modeled over two positions with loose restraints applied to C−C
b
t
distances. The Bu group is disordered and was modeled over two positions with each restrained to be equal and the carbon atoms of the minor
component isotropic.
Reactivity Studies: Aliphatic Electrophiles. The reac-
tivity of germanium alkoxides 2a−2c toward aliphatic electro-
philes is also in sharp contrast to the heavier isostructural
analogues. For instance, treatment of germanium tert-butoxide
2c with methyl iodide results in the formation of the
germanium(IV) cation, [(BDI)Ge(Me)OtBu)][I] (4), as a pale
yellow powder in 90% yield (eq 3). The methyl group resonates
Figure 2. ORTEP diagrams of [(BDI)Ge(Me)OtBu][I] 4 (left) and
[(BDI)Ge(Me)OsBu][OTf] 5b (right) with H atoms omitted and
BDI aryl groups C atoms minimized for clarity; ellipsoid probability
shown at 30%.
1
at δ 1.58 in the H NMR spectrum and δ 6.0 ppm in the 13C
NMR spectrum. Colorless flakelike crystals suitable for X-ray
structural analysis were obtained by leaving the C6D6 reaction
mixture overnight at room temperature.
Oxidative addition of (BDI)GeMe with methyl iodide has
already been reported by Roesky and co-workers; however, the
product was not crystallographically characterized.
The ORTEP diagram of 4 is shown in Figure 2. Selected
bond lengths and bond angles are listed in Table 3. Data
collection parameters are listed in Table 4. The metal center is
in a distorted tetrahedral coordination environment. The bond
lengths at the metal center are significantly shorter than that of
the precursor, tert-butoxide 2c, presumably due to the higher
oxidation state of the metal center of 4. However, the N−Ge−O
and N−Ge−N bond angles around germanium are slightly
larger. The Ge−C(20) bond length is 1.905(4) Å, which is
significantly shorter than both the divalent (BDI)GeMe
complex (2.002(4) Å) and the trivalent (BDI)Ge(S)Me
complex (2.009(2) Å), possibly due to the cationic nature of 4.
Similar reactivity was observed by treatment of sec-butoxide
2b and tert-butoxide 2c with the stronger electrophile, MeOTf,
resulting in the formation of cationic germanium(IV) complexes
[(BDI)Ge(Me)OR][OTf], 5b, and 5c (R = sBu, tBu). The 1H
NMR spectroscopic analysis shows the terminal methyl group
resonating at δ 1.44 (5b) and 1.62 (5c) ppm. The
corresponding 13C NMR spectroscopic resonances are
observed at δ 6.1 (5b) and 6.0 (5c) ppm. The 19F NMR
spectrum shows a singlet at δ −78.19 (5b) and −78.31 (5c) ppm,
corresponding to the anionic triflate group. Colorless crystals of
5b suitable for an X-ray diffraction study were obtained from a
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saturated tetrahydrofuran solution of 5b after two weeks at −27
°C (Figure 2). Similar to 4, the metal center of 5b possesses a
distorted tetrahedral coordination geometry. The bond lengths
and angles are also similar, with the exception of the longer
Ge−O bond and the more acute O−Ge−C and Ge−O−C
bond angles. These latter differences are attributed to the
different alkoxide groups on the germanium center.
The oxidative addition chemistry of the alkoxides was further
examined by treatment of tert-butoxide 2c with molecular
iodine, which results in the formation of the cationic complex
[(BDI)Ge(I)OtBu][I3], 6 (eq 4). This complex is presumably
Table 3. Selected Bond Lengths (Å) and Angles (deg) for
Compounds 4 and 5b
formed by the reaction of the iodide counterion of the transient
species, [(BDI)Ge(I)OtBu][I] with a further equivalent of
iodine, to give the more stabilizing counteranion, [I3]¯.
Compound 6 can be obtained in 92% yield as a dark orange
powder and was characterized by multinuclear NMR spectros-
copy, IR spectroscopy, as well as combustion analysis. The very
low field singlet resonance of the methinic γ-CH proton in the
1H NMR spectrum (δ 6.47 ppm) is reminiscent of the cationic
hypervalent germanium BDI complexes 4 (δ 6.10 ppm), 5b
(δ 5.99 ppm), and 5c (δ 6.04 ppm). Deep orange crystals
suitable for an X-ray diffraction study were grown from a
tetrahydrofuran/fluorobenzene mixture. Unfortunately, the X-ray
diffraction study of complex 6 did not give high quality data;
however, the connectivity was confirmed.
[LGe(Me)(OtBu)][I]
[LGe(Me)(OsBu)][OTf]
(4)
(5b)
Ge−O(1)
Ge−N(1)
Ge−N(2)
Ge−C(20) (30)
O−C(16) (32)
N(1)−Ge−O
N(2)−Ge−O
N(1)−Ge−N(2)
O−Ge−C(20)
1.723(3)
1.877(3)
1.7422(15)
1.8808(17)
1.8678(17)
1.910(2)
1.469(4)
107.11(7)
106.90(8)
98.40(7)
114.56(9)
112.43(9)
115.95(9)
121.2(2)
0.503
a
a
1.904(5)
1.479(7)
105.95(10)
98.62(15)
122.2(2)
N(1)−Ge−C(20)
N(2)−Ge−C(20)
Ge−O−C(16) (32)
110.74(13)
Reactivity Studies: Lewis Acids. In order to gauge the
Lewis base behavior of the germanium alkoxides, 2a−2c, a
tetrahydrofuran solution of tert-butoxide 2c was treated with
copper(I) iodide, to afford the germanium(II)−copper(I)
131.9(4)
0.607
b
Ge−C3N2 plane
a
b
N and N′ for 4. Distance between Ge and the plane defined by the
BDI-backbone (N−C−C−C−N plane).
Table 4. Crystallographic Data for Compound 4, 5b, and 7
a
b
c
[LGe(Me)(OtBu)][I] (4)
[LGe(Me)(OsBu)][OTf] (5b)···1.5THF
[{(BDI)GeOtBu}·CuI]2 · 3 C7H8 (7)
chemical formula
fw
C34H53GeIN2O
705.27
C82H130F6Ge2N4O11S2
1671.26
C66H100Cu2Ge2I2N4O2, 3(C7H8)
1784.02
T (K)
173(2)
173(2)
173(2)
wavelength (Å)
cryst size (mm3)
cryst syst
space group
a (Å)
0.710 73
0.710 73
0.710 73
0.40 × 0.30 × 0.25
orthorhombic
Pnma (No.62)
21.2060(4)
18.5239(7)
8.9409(3)
90
0.34 × 0.25 × 0.18
triclinic
0.14 × 0.06 × 0.04
monoclinic
C2/m (No.12)
15.7342(5)
16.4339(7)
16.7541(7)
90
P1 (No.2)
̅
12.7878(4)
13.0690(3)
13.4060(5)
86.982(2)
b (Å)
c (Å)
α (deg)
β (deg)
90
83.786(2)
102.306(2)
90
γ (deg)
V (Å3)
90
83.477(2)
3512.15(19)
4
2211.03(12)
1
4232.6(3)
2
Z
pc (Mg m−3)
1.33
1.26
1.40
−1
abs coeff (mm )
1.78
0.796
1.98
θ range for data collection (deg)
measured/indep reflns/R(int)
reflns with I > 2σ(I)
3.67−26.04
15 322/3538/0.065
2763
3.43−27.48
36 161/10 017/0.048
8565
3.51−27.11
22 306/4843/0.089
3319
data/restraints/params
GOF on F2
3538/24/208
1.016
10 017/84/514
1.041
4843/67/239
1.002
final R indices
R1 = 0.039, wR2 = 0.086
R1 = 0.057, wR2 = 0.095
0.53 and −0.91
R1 = 0.043, wR2 = 0.109
R1 = 0.055, wR2 = 0.117
0.65 and −0.39
R1 = 0.052, wR2 = 0.091
R1 = 0.095, wR2 = 0.103
R indices (all data)
largest diff peak and hole (e Å3)
1.01 and −0.59
a
b
The Bu group was included as disordered across the mirror plane and with restraints on the C−C(Me) and C(Me)···C(Me) distances. The sec-
butoxy group was disordered over two positions. It was not possible to distinguish between the carbon and oxygen atom positions on either THF
solvate; they were therefore refined with carbon at 80% occupancy and oxygen at 20% occupancy for each position. The THF molecule on the
c
inversion center was also modeled with all atoms left isotropic. The tBu group disordered about a mirror plane and was refined with carbon atoms
i
left isotropic. One of the Pr groups is disordered over two positions; the toluene solvates are disordered about special positions.
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adduct {μ1-Cu2I2}[(BDI)GeOtBu]2 7 in 61% yield (eq 5). The
there is a planar arrangement of the germanium, oxygen, carbon
(C16), copper, and iodide atoms (Figure 4). The bond lengths
1H NMR spectrum reveals a broad resonance for the isopropyl
methine protons (δ 3.46 ppm); unfortunately, sharper singles
were not observed upon heating to 40 °C and cooling to −60 °C
of the d8-THF NMR sample.
Complex 7 crystallizes from a saturated toluene solution after
a month and a half at −27 °C (Figure 3). Selected bond lengths
and angles are listed in Table 5. Data collection parameters are
Figure 4. POV-Ray diagram of the core of 7. Only C16, Cu, Ge, I, N,
and O atoms are shown for clarity. Color code: C16, gray; Cu, copper,
Ge, turquoise; I, purple; N, blue; O, red.
around the germanium center are in between that of the parent
alkoxide 2c and cationic complex 4, indicating a slight increase
of positive charge around the germanium center due to electron
donation into the empty s orbital of Cu(I).
Only a few other complexes possessing Cu−Ge bonds are
known. The Ge−Cu distance of 7 (2.3341(10) Å) is longer than
that observed by Mochida and co-workers for their series of
copper−germylene complexes, [(iPr-nacnac)Cu−Ge(X)(iPr-nac-
nac)] (Ge−Cu bond length: X = Cl, 2.3109(4) Å; X = H,
i
2.2980(8), X = Me 2.3165(3), Pr-nacnacH = 2-(isopropylami-
no)-4-(isopropylimino)-2-pentene).17 It is also longer than that
reported by Tolman and co-workers in their [(BDI)CuGeY]
complexes (Ge−Cu bond length: Y = [(NMes)2(CH)2],
2.2138(4) Å; Y = [N(SiMe3)2)]2, 2.2492(4) Å).18 However,
our Ge−Cu bond length is shorter than reported by Leung and
co-workers. In their system, four germanium complexes,
[Ge{N(SiMe3)C(Ph)C(SiMe3)(C5H4N-2)}Cl], are coordinated
to each copper vertex of a Cu4I4 cubane cluster.19
The Cu2I2 ring of complex 7 has a rhomboidal shape. The
Cu−I bond lengths of 2.5791(9) and 2.6382(9) Å are similar to
other rhomboidal Cu2I2 complexes, with a standard bond length
of between 2.50 and 2.57 Å for symmetric systems,20−23 or 2.54
and 2.64 Å for asymmetric systems.20,24 This latter type of
bonding can arise from the weak interaction of two LCuI
monomers.25 The Cu−I−Cu′ and I−Cu−I′ angles are 78.37(3)°
and 101.63°, respectively. The Cu···Cu′ distance in is 3.297(2) Å,
too far for any Cu−Cu bonding interaction to occur.21,25,26
Compound 7 is the second example in which a Cu2X2 unit
(X = Cl, Br, I) possesses three-coordinate copper centers
bound to another metal.27 The other known example is
[Cp2ReHCuI]2;27 however, instead of the standard planar
Cu2I2 arrangement, the Cu2I2 unit is folded, resulting in a short
Cu···Cu′ distance of 2.552(4) Å, indicative of a formal Cu−Cu
bond.21,25,26 Other examples the Cu2X2 unit with a M−Cu bond,
but a higher coordination number at copper, include Mo(W)−S
clusters,28 Mo−Sb clusters,29 an Fe−(CO) cluster,30 vinylidene-
Figure 3. ORTEP diagram of {μ1-Cu2I2}{(BDI)GeOtBu]2 7 with H
atoms omitted and BDI aryl group C atoms minimized for clarity;
ellipsoid probability shown at 30%.
Table 5. Selected Bond Lengths (Å) and Angles (deg) for
Compound 7
Ge−O
Ge−N
Ge−Cu
Cu−I
Cu−I′
O−C16
Cu···Cu′
I···I
1.781(4)
1.964(3)
2.3341(10)
2.6382(9)
2.5791(9)
1.447(7)
3.297(2)
4.0443(9)
N−Ge−N″
N−Ge−O
N−Ge−Cu
O−Ge−Cu
C16−O−Ge
Ge−Cu−I
Ge−Cu−I′
Cu−I−Cu′
I−Cu−I′
91.3(2)
96.87(14)
113.29(10)
135.71(14)
125.3(4)
and aminocarbyne-bridged heterobimetallic complexes,31,32
a
centrosymmetric [Cu4I8]4‑ complex,33 and a Cu2X2 unit
coordinated at each copper by two SbPh3 ligands.34
116.99(4)
141.37(4)
78.37(3)
101.63(3)
CONCLUSIONS
■
Ge−C3N2 plane
0.865
A series of germylene alkoxide complexes have been
synthesized. In contrast to the isostructural tin and lead
systems, germanium(II) β-dikeiminate alkoxide complexes do
given in Table 4. The molecule lies on a crystallographical
mirror plane and possesses an inversion center. As a result,
1548
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Inorganic Chemistry
Article
2H, CHMe2), 1.51 (s, 3H, NCMe), 1.50 (s, 3H, NCMe), 1.48 (d, J =
7.4 Hz, 6H, CHMe), 1.34 (d, J = 6.3 Hz, 6H, CHMe), 1.33 (d, J = 6.4
Hz, 6H, CHMe), 1.19 (d, J = 6.9 Hz, 7H), 1.08−0.94 (m, 2H,
OC(Me)CH2Me), 0.45 (d, J = 6.2 Hz, 3H, OCH(Me)Et), 0.26 (t, J =
7.4, 3H, OCH(Me)CH2Me). 13C{1H } NMR (400 MHz, C6D6):
δ 163.24 (NCMe), 144.17 (ipso-C), 137.03 (Ar−C), 126.59 (Ar−C),
124.13 (Ar -C), 124.02 (Ar−C), 95.20 (γ-CH), 70.68 (OC(Me)Et),
33.37 (OCH(Me)CH2Me), 28.37 (NCMe), 28.25 (NCMe), 26.24
(CHMe), 24.41 (CHMe), 23.02 (CHMe), 22.34 (CHMe), 21.77
(CHMe), 20.38 (OCH(Me)Et), 10.02 (OCH(Me)CH2Me). IR
(Nujol, υ/cm−1): 1557, 1522, 1320, 1175, 1018, 918, 795. Anal.
Calcd for C33H50GeN2O: C, 70.35; H, 8.95; N, 4.97. Found: C, 70.46;
H, 9.01; N 4.87.
not activate carbon dioxide, further supporting the dependence
on the metal−oxygen bond dissociation energy being key for
such a reaction to occur; that is, reactivity toward insertion
increases with decreasing BDE. Alkoxides 2a−2c also present a
different reactivity toward aliphatic electrophiles, resulting in
the formation of cationic oxidative addition products. This
reactivity is a result of the germanium lone pair being more
energetically accessible than the oxygen’s one, as well as
divalent germanium’s propensity to be oxidized to its
tetravalent state. The pronounced Lewis base behavior of the
germanium center was also confirmed by the addition of
copper(I) iodide, which results in the formation of a Ge(II)−
Cu(I) adduct, possessing an unusual planar Cu2I2 ring bridging
two metal centers.
[CH{(CH3)CN-2,6-iPr2C6H3}2GeOtBu] (2c). Orange crystals suit-
able for an X-ray crystallographic study of (BDI)GeOtBu 2c can be
1
obtained in a similar way to 2a in 76% yield. H NMR (400 MHz,
C6D6, 303 K): δ 7.25 − 6.96 (m, 6H, Ar−H), 4.61 (s, 1H, γ-CH), 3.82
(m, 2H, CHMe2), 3.34 (sept, J = 6.8 Hz, 2H, CHMe2), 1.51 (s, 6H,
NCMe), 1.50 (d, J = 7.2 Hz, 6H, CHMe), 1.33 (d, J = 6.8 Hz, 6H,
CHMe), 1.16 (d, J = 6.9 Hz, 6H, CHMe), 1.10 (d, J = 6.8 Hz, 6H,
CHMe), 0.78 (s, 9H, OCMe3). 13C{1H} NMR (400 MHz, CDCl3):
δ 163.61 (NCMe), 145.16 (ipso-C), 139.66 (Ar−C), 126.45 (Arp−C),
124.66 (Ar−C), 123.71 (Ar−C), 96.03 (γ-CH), 70.00 (OCMe3), 33.21
(OCMe3), 28.47 (NCMe), 27.08 (NCMe), 26.46 (CHMe2), 25.82
(CHMe2), 24.86 (CHMe), 22.44 (CHMe). IR (Nujol, υ/cm−1): 1553,
1520, 1322, 1260, 1175, 1100, 1020, 935, 795. Anal. Calcd for
C33H50GeN2O: C, 70.35; H, 8.95; N, 4.97. Found: C, 70.49; H, 9.05;
N, 4.90.
EXPERIMENTAL SECTION
■
General. All manipulations were carried out in an atmosphere of
dry nitrogen using standard Schlenk techniques or in an inert-
atmosphere glovebox. Solvents were dried from the appropriate drying
agent, distilled, degassed, and stored over 4 Å sieves. (BDI)H and
(BDI)GeCl were prepared according to literature procedures,35
although a slightly modified procedure was used in the synthesis of
GeCl2(diox). Potassium alkoxide salts were prepared by the slow
addition of the relevant alcohol (dried and distilled) to a suspension of
potassium hydride. Methyl iodide and methyl trifluoromethanesulfo-
nate were freshly dried and distilled before use. Carbon dioxide was
used as received (Union Carbide, 99.999%). 1H and 13C NMR spectra
were recorded on a Varian 400 MHz or Varian 500 MHz
spectrometer. 1H and 13C NMR spectroscopic chemical shifts are
given relative to residual solvent peaks, and the 19F chemical shifts
were externally referenced to CFCl3. The data for the X-ray structures
were collected at 173 K on a Nonius Kappa CCD diffractometer,
k(Mο Kα) = 0.710 73 Å and refined using the SHELXL-97 software
package.36
[CH{(CH3)CN-2,6-iPr2C6H3}2Ge(Me)OtBu]I (4). MeI (7.8 μL,
0.12 mmol) was added to a stirring toluene solution (5 mL) of
(BDI)GeOtBu 2c (70 mg, 0.12 mmol). After 1 h, the solution turned a
pale yellow, and a pale yellow precipitate was formed. The volatiles
were removed, and the solid was washed with cold pentane affording a
pale yellow powder of [(BDI)Ge(Me)OtBu]I 4 in 90% yield (78 mg).
Colorless crystals suitable for an X-ray crystallographic study can be
obtained by performing the reaction without stirring and leaving the
reaction mixture overnight at room temperature. 1H NMR (500 MHz,
CD2Cl2): δ 7.51 (t, J = 7.8, 2H, Ar−H), 7.38 (d, J = 7.8, 4H, Ar−H),
6.10 (s, 1H, γ-CH), 3.14 (m, 2H, CHMe2), 2.92 (m, 2H, CHMe2),
2.18 (s, 6H, NCMe), 1.58 (s, 3H, GeMe), 1.43 (d, J = 6.8 Hz, 6H,
CHMe2), 1.36 (d, J = 6.7 Hz, 6H, CHMe2), 1.34 (d, J = 6.6 Hz, 6H,
CHMe2), 1.14 (d, J = 6.8 Hz, 6H, CHMe2), 0.74 (s, 9H, OCMe). 13C{1H }
NMR (400 MHz, CD2Cl2): δ 173.60 (NCMe), 145.31 (ipso-C),
130.28 (Ar−C), 125.67 (Ar−C), 125.39 (Ar−C), 100.75 (γ-CH),
75.58 (OCMe3), 31.39 (OCMe3), 29.14 (NCMe), 28.01 (NCMe),
25.29 (CHMe2), 24.99 (CHMe2), 24.51 (CHMe), 23.61 (CHMe), 6.0
(GeMe). IR (Nujol, υ/cm−1): 3059, 1624, 1553, 1363, 1253, 1176,
1101, 935, 799, 785, 758. Anal. Calcd for C34H53GeIN2O: C, 57.90; H,
7.57; N, 3.97. Found: C, 57.84; H, 7.55; N, 3.91.
37
[GeCl2·(dioxane)]. GeCl4 (20 mL, 87.7 mmol) and 1,4-dioxane
(15 mL) were dissolved in a 1:1 hexane:Et2O mixture (100 mL). To
this mixture was added nBu3SnH (25 mL, 92.9 mmol). After stirring at
room temperature for 30 min, a white precipitate appeared. This was
filltered off, washed with cold hexane, and identified as the pure
GeCl2(diox) (2 g). The mother liquor was left at room temperature
for 2 days, affording white crystals of GeCl2(diox) (17.0 g) upon
standing, for a total combined yield of 84%. Note that repeated
experiments on a smaller scale resulted in a considerably lower yield
(10−18%).
[CH{(CH3)CN-2,6-iPr2C6H3}2GeOiPr] (2a). A suspension of KOiPr
(94 mg, 0.95 mmol) in THF (5 mL) was added to a solution of
(BDI)GeCl (0.50 g, 0.95 mmol) in THF (5 mL) at room temperature,
and the reaction mixture was stirred for 3 days. The solvent was
removed under vacuum, the orange crude product was extracted with
toluene, and the solution was filtered through celite. Removal of the
volatiles and recrystallization from hexane overnight at −27 °C
[CH{(CH3)CN-2,6-iPr2C6H3}2Ge(Me)OsBu]OTf (5b). (BDI)-
GeOsBu 2b (230 mg, 0.41 mmol) was dissolved in pentane (5 mL)
and treated with methyl triflate (45 μL, 0.41 mmol). The reaction
mixture was stirred for 1 h, after which a pale yellow precipitate was
formed. The solution was decanted and the residue washed with
pentane. Storage of a saturated THF solution at −27 °C for 2 weeks
yielded colorless crystals of [(BDI)Ge(Me)OtBu]OTf 5b (229 mg,
77%), suitable for X-ray crystallography. 1H NMR (399 MHz,
CDCl3): δ 7.29 (m, 6H, Ar−H), 5.99 (s, 1H, γ-CH), 3.28 (m, 1H,
OCH(Me)Et), 3.12 (m, 2H, CHMe2), 3.03 (m, 2H, CHMe2), 2.13 (s,
3H, NCMe), 2.11 (s, 3H, NCMe), 1.44 (s, 3H, GeMe), 1.29 (d, 6H, J =
5.8, CHMe), 1.27 (m, 2H, OC(Me)CH2Me), 1.14 (d, 6H, J = 6.9 Hz,
CHMe), 1.06 (d, 6H, J = 6.8 Hz, CHMe), 0.81 (d, 6H, J = 6.8 Hz,
CHMe), 0.32 (d, 3H, J = 6.0 Hz, OCH(Me)Et), 0.15 (t, 3H, J = 7.5
Hz, OCH(Me)CH2Me). 13C{1H } NMR (399 MHz, CDCl3): δ 172.7
(NCMe), 145.2 (ipso-C), 130.0 (Ar−C), 125.1 (Ar−C), 123.4 (Ar−C),
102.1 (γ-CH), 74.8 (OCH(Me)Et), 28.7 (NCMe), 27.4 (CHMe), 24.8
(CHMe), 24.4 (OCH(Me)CH2Me), 23.8 (CHMe), 22.4 (OCH(Me)-
Et), 9.18 (O(Me)CH2Me), 0.0 (GeMe). 19F NMR (400 MHz,
CDCl3): δ −78.31. IR (Nujol, υ/cm−1): 1549, 1378 (s), 1370 (s),
1323, 1269 (s), 1235, 1150, 1110, 1032 (s), 955, 810, 762, 637. Anal.
afforded orange crystals of (BDI)GeOiPr 2a (0.38 g, 72%). H NMR
1
(400 MHz, C6D6, 303 K): δ 7.17−7.02 (m, 6H, Ar-H), 4.64 (s, 1H,
γ-CH), 3.73 (m, 3H, CHMe2 + OCHMe2), 3.34 (m, 2H, CHMe2),
1.51 (s, 6H, NCMe), 1.49 (d, J = 6.8 Hz, 6H, CHMe), 1.17 (d, J = 6.9
Hz, 6H, CHMe), 1.10 (d, J = 6.8 Hz, 6H, CHMe), 0.57 (d, J = 6.1 Hz,
6H, OCHMe). 13C{1H} NMR (400 MHz, CDCl3): δ 163.29 (NCMe),
145.04 (ipso-C), 139.20 (Ar−C), 126.45 (Ar−C), 124.66 (Ar−C),
123.97 (Ar−C), 94.99 (γ -CH), 64.93 (OCHMe2), 28.40 (NCMe),
27.97 (NCMe), 26.31 (CHMe),24.45 (CHMe), 24.24 (CHMe), 22.70
(CHMe), 22.31 (CHMe), 20.37 (CHMe). IR (Nujol, υ/cm−1): 1561,
1521, 1321, 1260, 1174, 1019, 964, 795. Anal. Calcd for C32H48GeN2O:
C, 69.96; H, 8.81; N, 5.10. Found: C, 69.84; H, 8.72; N, 4.92.
[CH{(CH3)CN-2,6-iPr2C6H3}2GeOsBu] (2b). Orange crystals suit-
able for an X-ray crystallographic study of (BDI)GeOsBu 2b can be
1
obtained in a similar way to 2a in 81% yield. H NMR (400 MHz,
C6D6, 303 K): δ 7.20−7.02 (m, 6H, Ar-H), 4.66 (s, 1H, γ-CH), 3.84−
3.68 (m, 2H, CHMe2), 3.55−3.43 (m, 1H, OCH(Me)Et), 3.37 (m,
1549
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Inorganic Chemistry
Article
Calcd for C35H35F3N2O4GeS: C, 57.78; H, 7.34; N, 3.85. Found: C,
57.83; H, 7.40; N, 3.76.
Present Address
†School of Chemical and Physical Sciences, Victoria University
of Wellington, PO Box 600, Wellington, New Zealand.
[CH{(CH3)CN-2,6-iPr2C6H3}2Ge(Me)OtBu]OTf (5c). [(BDI)Ge-
(Me)OsBu]OTf 5c can be obtained as a pale yellow powder in 72%
1
yield using a similar methodology for the generation of 5b. H NMR
ACKNOWLEDGMENTS
(399 MHz, CDCl3): δ 7.36 (m, 6H, Ar−H), 6.04 (s, 1H, γ-CH), 3.16
(m, 2H, CHMe2), 3.06 (sept, 2H, J = 6.6, CHMe2), 2.15 (s, 6H,
NCMe), 1.62 (s, 3H, GeMe), 1.40 (d, 6H, J = 6.8, CHMe), 1.32 (d,
6H, J = 6.7, CHMe), 1.31 (d, 6H, J = 6.5, CHMe), 1.11 (d, 6H, J = 6.9,
CHMe), 0.71 (s, 9H, OCMe3). 13C{1H } NMR (399 MHz, CDCl3):
δ 173.6 (NCMe), 146.0 (ipso-C), 130.0 (Ar−C), 125.6(Ar−C), 124.9
(Ar−C), 120.9 (SO3CF3), 101.7 (γ -CH), 88.5 (OCMe3), 31.56
(OCMe3), 29.07 (NCMe), 27.7 (CHMe2), 25.5 (CHMe2), 25.1
(CHMe), 24.7 (CHMe), 24.0 (CHMe), 23.8 (CHMe), 6.1 (GeMe).
19F NMR (400 MHz, CDCl3): δ −78.19. IR (Nujol, υ/cm−1): 1544,
1377 (s), 1366 (s), 1318, 1266 (s), 1223, 1149, 1106, 1030 (s), 947,
894 (w), 808, 752, 637. Anal. Calcd for C35H35F3N2O4GeS: C, 57.78;
H, 7.34; N, 3.85. Found: C, 57.99; H, 7.48; N, 3.73.
■
The authors are grateful for the financial support from the
EPSRC (L.F., Grant EP/E032575/1).
REFERENCES
■
(1) Tam, E. C. Y.; Johnstone, N. C.; Ferro, L.; Hitchcock, P. B.;
Fulton, J. R. Inorg. Chem. 2009, 48, 8971−8976.
(2) Ferro, L.; Hitchcock, P. B.; Coles, M. P.; Cox, H.; Fulton, J. R.
Inorg. Chem. 2011, 50, 1879−1888.
(3) Harris, L. A. M.; Coles, M. P.; Fulton, J. R. Inorg. Chim. Acta
2011, 369, 97−102.
(4) Yao, S. L.; Brym, M.; Merz, K.; Driess, M. Organometallics 2008,
27, 3601−3607.
(5) Saur, I.; Alonso, S. G.; Gornitzka, H.; Lemierre, V.; Chrostowska,
A.; Barrau, J. Organometallics 2005, 24, 2988−2996.
(6) Driess, M.; Yao, S. L.; Brym, M.; van Wullen, C. Angew. Chem.,
Int. Ed. 2006, 45, 4349−4352.
(7) Yang, Y.; Roesky, H. W.; Jones, P. G.; So, C. W.; Zhang, Z. S.;
Herbst-Irmer, R.; Ye, H. Q. Inorg. Chem. 2007, 46, 10860−10863.
(8) Doyle, D. J.; Hitchcock, P. B.; Lappert, M. F.; Li, G. J. Organomet.
Chem. 2009, 694, 2611−2617.
(9) Pineda, L. W.; Jancik, V.; Roesky, H. W.; Necuali, D.; Neculai, A. M.
Angew. Chem., Int. Ed. 2004, 43, 1419−1421.
(10) Pineda, L. W.; Jancik, V.; Roesky, H. W.; Herbst-Irmer, R. Inorg.
Chem. 2005, 44, 3537−3540.
(11) Pineda, L. W.; Jancik, V.; Colunga-Valladares, J. F.; Roesky, H. W.;
Hofmeister, A.; Magull, J. Organometallics 2006, 25, 2381−2383.
(12) Pineda, L. W.; Jancik, V.; Roesky, H. W.; Herbst-Irmer, R.
Angew. Chem., Int. Ed. 2004, 43, 5534−5536.
(13) Pineda, L. W.; Jancik, V.; Oswald, R. B.; Roesky, H. W.
Organometallics 2006, 25, 2384−2387.
[CH{(CH3)CN-2,6-iPr2C6H3}2Ge(I)OtBu]I3 (6). Iodine (46 mg,
0.24 mmol) was added to a toluene solution (5 mL) of (BDI)GeOtBu
2c (52 mg, 0.09 mmol). The reaction mixture was stirred overnight
producing a pale precipitate. The solution was decanted, and the
precipitate was washed several times with pentane, affording
[(BDI)Ge(I)OtBu]I3 6, a dark orange powder in 92% yield (89
mg). Dark red crystals were obtained by storing a THF/C6H5F
1
solution of 6 at −27 °C for one week. H NMR (400 MHz, CDCl3):
δ 7.50 (t, J = 7.8, 2H, Ar−H), 7.40 (d, J = 7.8, 2H, Ar−H), 7.34 (d, J =
7.8, 2H, Ar−H), 6.47 (s, 1H, γ-CH), 3.24 (m, 2H, CHMe2), 3.11 (m,
2H, CHMe2), 2.33 (s, 6H, NCMe), 1.43 (d, J = 6.8 Hz, 6H, CHMe2),
1.40 (d, J = 7.5 Hz, 6H, CHMe2), 1.38 (d, J = 7.1 Hz, 6H, CHMe2),
1.11 (d, J = 6.8 Hz, 6H, CHMe2), 0.90 (s, 9H, OCMe3). 13C{1H }
NMR (400 MHz, CDCl3): δ 174.75 (NCMe), 146.68 (ipso-C), 130.80
(Ar−C), 126.53 (Ar−C), 125.04 (Ar−C), 102.83 (γ-CH), 82.80
(OCMe3), 31.57 (OCMe3), 29.57 (NCMe), 28.94 (NCMe), 28.00
(CHMe2), 25.54 (CHMe2), 25.01 (CHMe), 23.56 (CHMe). IR
(Nujol, υ/cm−1): 1541, 1519, 1317, 1251, 1158, 1024, 933, 810. Anal.
Calcd: C, 37.01 ; H, 4.71; N, 2.62. Found: C, 36.86; H, 4.62; N, 2.49.
{μ-(CuI)2}[CH{(CH3)CN-2,6-iPr2C6H3}2GeOtBu]2 (7). THF (5 mL)
was added to a stirring solid mixture of CuI (18 mg, 0.09 mmol) and
(BDI)GeOtBu 15c (52 mg, 0.09 mmol). After stirring for 3 days,
volatiles were removed under vacuum and the resulting precipitate was
extracted with toluene and filtered through celite. Removal of the
volatiles and washing with cold pentane afforded (BDI)Ge(OtBu)CuI
7 as a bright yellow powder in 61% yield (43 mg). Storage at −27 °C
for one month of a concentrated toluene solution of 7 afforded pale
(14) Jana, A.; Ghoshal, D.; Roesky, H. W.; Objartel, I.; Schwab, G.;
Stalke, D. J. Am. Chem. Soc. 2009, 131, 1288−1293.
(15) Jana, A.; Nekoueishahraki, B.; Roesky, H. W.; Schulzke, C.
Organometallics 2009, 28, 3763−3766.
(16) Maksic, Z. B.; Kovacevic, B. J. Chem. Soc., Perkin Trans. 2 1999,
2623−2629.
(17) Arii, H.; Nakadate, F.; Mochida, K. Organometallics 2009, 28,
4909−4911.
1
yellow crystals suitable for an X-ray crystallographic study. H NMR
(18) York, J. T.; Young, V. G.; Tolman, W. B. Inorg. Chem. 2006, 45,
4191−4198.
(400 MHz, d8-THF): δ 7.21 (m, 12H, Ar−H), 5.01 (s, 2H, γ-CH),
3.56 (br, 8H, CHMe2), 1.76 (s, 12H, NCMe), 1.44 (d, J = 5.9 Hz, 12H,
CHMe2), 1.39 (d, J = 6.8 Hz, 12H, CHMe2), 1.27 (d, J = 6.7 Hz, 12H,
CHMe2), 1.13 (d, J = 6.8 Hz, 12H, CHMe2), 0.67 (s, 18H, OCMe3).
13C{1H} NMR (400 MHz, d8-THF): δ 165.74 (NCMe), 145.11 (ipso-
C), 135.59 (Ar−C), 123.58 (Ar−C), 122.72 (Ar−C), 99.03 (γ-CH),
67.93 (OCMe3), 32.87 (OCMe3), 28.61 (NCMe), 28.20 (NCMe),
24.81 (CHMe2), 23.85 (CHMe2), 22.45 (CHMe), 22.21 (CHMe). IR
(Nujol, υ/cm−1): 2321, 1523, 1261, 1097, 1020, 936, 802. Repeated
attempts of obtaining elemental analysis for compound 7 were
unsuccessful. The 1H NMR spectrum of the crystals of 7 is consistent
with that of the product formed upon initial reaction.
(19) Leung, W. P.; So, C. W.; Chong, K. H.; Kan, K. W.; Chan, H. S.;
Mak, T. C. W. Organometallics 2006, 25, 2851−2858.
(20) Healy, P. C.; Pakawatchai, C.; Raston, C. L.; Skelton, B. W.;
White, A. H. J. Chem. Soc., Dalton Trans. 1983, 1905−1916.
(21) Bowmaker, G. A.; Boyd, S. E.; Hanna, J. V.; Hart, R. D.; Healy,
P. C.; Skelton, B. W.; White, A. H. J. Chem. Soc., Dalton Trans. 2002,
2722−2730.
(22) Oakley, S. H.; Coles, M. P.; Hitchcock, P. B. Inorg. Chem. 2004,
43, 5168−5170.
(23) Allen, D. W.; Mifflin, J. P. L; Coles, S. Chem. Commun. 1998,
2115−2116.
(24) Oakley, S. H.; Soria, D. B.; Coles, M. P.; Hitchcock, P. B. Dalton
Trans. 2004, 537−546.
ASSOCIATED CONTENT
■
S
* Supporting Information
(25) Soloveichik, G. L.; Eisenstein, O.; Poulton, J. T.; Streib, W. E.;
Huffman, J. C.; Caulton, K. G. Inorg. Chem. 1992, 31, 3306−3312.
(26) Alemany, P.; Alvarez, S. Inorg. Chem. 1992, 31, 4266−4275.
(27) Belsky, V. K.; Ishchenko, V. M.; Bulychev, B. M.; Soloveichik, G. L.
Polyhedron 1984, 3, 749−752.
Crystallographic data for 2a, 2b, 2c, 4, 5b, and 7 (CIF). NMR
spectrum of 7. This material is available free of charge via the
Internet at http://pubs.acs.org.
(28) Hou, H. W.; Long, D. L.; Xin, X. Q.; Huang, X. X.; Kang, B. S.;
Ge, P.; Ji, W.; Shi, S. Inorg. Chem. 1996, 35, 5363−5367.
(29) Ly, H. V.; Parvez, M.; Roesler, R. Inorg. Chem. 2006, 45, 345−
351.
AUTHOR INFORMATION
■
Corresponding Author
*E-mail: j.robin.fulton@vuw.ac.nz.
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Article
(30) Shieh, M.; Miu, C. Y.; Lee, C. J.; Chen, W. C.; Chu, Y. Y.; Chen,
H. L. Inorg. Chem. 2008, 47, 11018−11031.
(31) Albano, V. G.; Busetto, L.; Cassani, M. C.; Sabatino, P.; Schmitz,
A.; Zanotti, V. J. Chem. Soc., Dalton Trans. 1995, 2087−2093.
(32) Pogrebnyakov, D. A.; Starikova, Z. A.; Pavlenko, N. I.; Rubailo,
A. I.; Sokolenko, V. A.; Chudin, O. S.; Antonova, A. B. Russ. Chem. B+
2002, 51, 1339−1340.
(33) Hartl, H. Angew. Chem., Int. Ed. Engl. 1987, 26, 927−928.
(34) Bowmaker, G. A.; Hart, R. D.; deSilva, E. N.; Skelton, B. W.;
White, A. H. Aust. J. Chem. 1997, 50, 621−626.
(35) Ding, Y. Q.; Roesky, H. W.; Noltemeyer, M.; Schmidt, H. G.;
Power, P. P. Organometallics 2001, 20, 1190−1194.
(36) Sheldrick, G. M. Acta Crystallogr., Sect. A 2008, 64, 112−122.
(37) Fjeldberg, T.; Haaland, A.; Schilling, B. E. R.; Lappert, M. F.;
Thorne, A. J. J. Chem. Soc., Dalton Trans. 1986, 1551−1556.
1551
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