New germanium complexes containing ligands based on 4,6-Di-tert-butyl-N-(2, 6-diisopropylphenyl)-o-iminobenzoquinone in different redox states

Article abstract of DOI:10.1002/ejic.200701115

The exchange reaction of lithium o-amidophenolate, (AP)Li₂, derived from the reaction of 4,6-di-tert-butyl-N-(2,6-diisopropylphenyl)-o- iminobenzoquinone (imQ) with GeCl₄ in hexane or thf leads to (AP)₂Ge (1) (AP is a dianion of imQ). The latter was also obtained by the interaction of GeCl₂·dioxane and (ISQ)Li in toluene (ISQ is a radical anion of imQ). The reaction of (AP)Li₂ with GeCl ₂·dioxane in thf results in the formation of germylene 2, [(AP)Ge (2)], which reduces neutral imQ to give compound 1. The exposure of 1 in thf to anhydrous HCl in a 1:1 molar ratio leads to its o-aminophenolato derivative, (AP)(APH)GeCl (3). Free imQ inserts into the Ge-H bond of (C ₆F₅)₃GeH in thf to give (C₆F ₅)₃Ge(APH) (4). It is another way of obtaining complexes with protonated ligands such as APH. Compound 3 can be easily oxidized by air to form the stable paramagnetic complex (AP)(ISQ)GeCl (5). Complexes 1 and 3-5 were structurally investigated by using single-crystal X-ray diffraction. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.

Full text of DOI:10.1002/ejic.200701115

FULL PAPER
DOI: 10.1002/ejic.200701115
New Germanium Complexes Containing Ligands Based on 4,6-Di-tert-butyl-
N-(2,6-diisopropylphenyl)-o-iminobenzoquinone in Different Redox States
Alexandr V. Piskunov,*[a] Igor A. Aivaz’yan,[a] Andrey I. Poddel’sky,[a] Georgii K. Fukin,[a]
Evgenii V. Baranov,[a] Vladimir K. Cherkasov,[a] and Gleb A. Abakumov[a]
Keywords: Germanium / Metallacycles / N,O ligands / EPR spectroscopy / X-ray diffraction
The exchange reaction of lithium o-amidophenolate, (AP)Li2,
derived from the reaction of 4,6-di-tert-butyl-N-(2,6-diisopro-
olato derivative, (AP)(APH)GeCl (3). Free imQ inserts into
the Ge–H bond of (C6F5)3GeH in thf to give (C6F5)3Ge(APH)
pylphenyl)-o-iminobenzoquinone (imQ) with GeCl4 in hex- (4). It is another way of obtaining complexes with protonated
ane or thf leads to (AP)2Ge (1) (AP is a dianion of imQ). The
latter was also obtained by the interaction of GeCl2·dioxane
and (ISQ)Li in toluene (ISQ is a radical anion of imQ). The
reaction of (AP)Li2 with GeCl2·dioxane in thf results in the
formation of germylene 2, [(AP)Ge (2)], which reduces neu-
tral imQ to give compound 1. The exposure of 1 in thf to
anhydrous HCl in a 1:1 molar ratio leads to its o-aminophen-
ligands such as APH. Compound 3 can be easily oxidized by
air to form the stable paramagnetic complex (AP)(ISQ)GeCl
(5). Complexes 1 and 3–5 were structurally investigated by
using single-crystal X-ray diffraction.
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2008)
(imQ) (Scheme 1) is of interest. In comparison with diaza-
butadienes, the substitution of one imino fragment by a car-
bonyl function appreciably changes both the steric situation
in the coordination sphere of the metal and the redox prop-
erties of the active ligand.
Introduction
Diamide ligands were shown to be very useful in ob-
taining stable derivatives of group 14 elements,[1,2] particu-
larly germanium,[1g–1k] in the divalent state. A significant
part of these compounds is based on diazabutadiene-type
ligands. One of their most important features is the ability
to form not only dianion derivatives but radical anion com-
plexes containing divalent germanium.[1h–1g] Redox-active
ligands like diazabutadienes, which can be involved in redox
reactions without losing their coordination ability, are of
special interest. The introduction of such ligands into the
metal coordination sphere will expand its reactivity. More-
over, EPR spectroscopy gives essential information about
the structure and behaviour of this type of compounds.
However, diazabutadiene derivatives are quite rare in GeIV
chemistry. To date, only a few tetravalent germanium di-
amides on the basis of substituted diazabutadienes have
been described.[2a–2d] All of these compounds include non-
chelating groups besides the diamide ligand. The existence
of more than one diazabutadiene ligand in a germani-
um(IV) environment was shown to be impossible.[1c] Never-
theless, the use of benzannulated diamides yields the GeN4
core.[2e–2f] In accordance with the preceding discussion, the
chemistry of complexes based on the benzannulated 4,6-di-
tert-butyl-N-(2,6-diisopropylphenyl)-o-iminoquinone ligand
Scheme 1.
Recently we have reported the synthesis of tin complexes
with o-amidophenolato ligands on the basis of imQ con-
taining one or two o-iminoquinone substituents and the
metal in different valence states,[3] (Scheme 2) in contrast to
the corresponding diamido complexes.[1b,1c,1e] Afterwards,
the stable radical tin derivative based on this ligand has
been obtained and structurally characterized.[4]
It is noteworthy that the whole potential versatility of o-
iminoquinone complexes, such as ability of the ligand to
exist in the protonated state, was not manifested for tin de-
rivatives. In the present paper we show the versatile behav-
iour of imQ as the ligand that is able to exist in different
redox and valent states by the example of germanium com-
plexes.
[a] G. A. Razuvaev Institute of Organometallic Chemistry of the
Russian Academy of Sciences
Tropinina Str. 49, 603950, Nizhny Novgorod, GSP-445, Russia
Fax: +7-8314-627497
E-mail: pial@iomc.ras.ru
Eur. J. Inorg. Chem. 2008, 1435–1444
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
1435

A. V. Piskunov et al.
FULL PAPER
Complex 1 can be obtained in another way by using
GeCl2·dioxane and the lithium derivative, (ISQ)Li, of ISQ,
which is a radical anion of imQ, as the starting reagents
(Scheme 3). Lithium o-iminosemiquinolate was prepared by
the reaction of (AP)Li2 with an equimolar quantity of free
imQ in toluene. While the reactants were mixed, the dark-
blue colour of the lithium radical anion salt disappeared
and the reaction mixture turned colourless, indicating the
formation of a diamagnetic compound. The product was
isolated and identified as complex 1. We were unable to
obtain any evidence for the primary formation of derivative
Ge(ISQ)2 in this reaction; but if this is true, the triplet
germylene species should engage in a double radical recom-
bination reaction leading to complex 1.
The reaction of GeCl2·dioxane with (AP)Li2 in thf yields
the corresponding o-amidophenolate derivative on the basis
of the low-valent germanium(II) species, (AP)Ge (2)
(Scheme 4), as a red volatile viscous resin. Complex 2 did
not form crystals, neither from solution nor during subli-
mation. Even when stored for several months in a sealed
tube, it stayed amorphous.
Scheme 2.
Results and Discussion
To obtain germanium complexes with imQ-based li-
gands, we used exchange reactions of germanium chlorides
with alkali metal o-iminoquinone salts. Earlier this was
shown to be a suitable method to synthesize tin complexes
of the same type.[3,4] Lithium o-amidophenolate, (AP)Li2,[4]
reacts with tetrachlorogermane in hexane or thf solution to
yield the corresponding bis(o-amidophenolato) compound
(AP)2Ge (1) (Scheme 3). Complex 1 was isolated from hex-
ane as colourless crystals suitable for X-ray analysis.
Scheme 4.
Germylene 2 initially adds o-iminoquinone in toluene or
thf to give complex 1 (Scheme 5). The product of imQ ad-
dition to (AP)Ge (2) was identified by melting point and
1H NMR analysis data.
Scheme 5.
Scheme 3.
The exposure of 1 in thf to anhydrous HCl in a 1:1 molar
It is noteworthy that, even when the reaction was carried ratio results in N–Ge bond cleavage and hydrogen chloride
out in the strongly coordinating thf solvent, the coordina- addition leading to (o-aminophenolato)germanium(IV) de-
tion number of the GeIV atom was four, in contrast to that rivative (AP)(APH)GeCl (3) (Scheme 6). Features of NH-
1
in the similar bis(o-amidophenolato)tin(IV) derivative derivative (AP)(APH)GeCl are demonstrated by H NMR
(AP)2Sn(thf)[3] and in the bis(catecholato)germanium(IV) and IR spectra.
complex,[5a] which contain pentacoordinate metal centres
due to a thf molecule bonded as a donor-acceptor.
Another way to synthesize o-aminophenolato germa-
nium derivatives is the insertion of o-iminoquinone into the
As we have found previously, the exchange reaction of Ge–H bond of germanes. (C6F5)3GeH reacts with imQ in
(AP)Li2 with Ph2SnCl2 in hexane is accompanied by a re- thf to give the corresponding o-aminophenolate, (C6F5)3-
dox side-reaction between tin(IV) and the o-amidophe- Ge(APH) (4) (Scheme 7).
nolato ligand to give o-iminosemiquinonate derivatives.[4] In
The considerable difference in the germanium coordina-
comparison with tin(IV), germanium(IV) is a relatively tion environment between complexes 3 and 4 results in the
weaker oxidant, and as a result, the redox reaction does not significant discrepancy in Ge–N bonding. The amine hy-
take place during the formation of complex 1.
drogen signal in the 1H NMR spectrum appears at a chemi-
1436
www.eurjic.org
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2008, 1435–1444

Ge Complexes with Iminobenzoquinone Ligands in Different Redox States
Scheme 6.
Scheme 7.
cal shift value of 7.08 ppm for 3 and 5.63 ppm for 4. More-
over, the νN–H absorption band in the IR spectra for 3 and
4 are 3262 and 3386 cm–1, respectively. NMR and IR spec-
troscopy data for 3 are typical for the coordinated amine
group,[6] while in 4 the NH-fragment stays uncoordinated.
This fact was confirmed by the structural investigations.
The o-aminophenolato ligand in 3 can easily be oxidized
by oxygen to the o-iminosemiquinonato substituent. The
process takes place in acetone under ambient conditions,
yielding the dark-green radical anion complex (AP)(ISQ)-
GeCl (5) (Scheme 8).
Figure 1. Experimental X-band EPR spectrum of 5 in toluene at
290 K (a) and its simulation (b).
Complex 5 is air-stable both in the solid state and in
It is necessary to note that complex 5 is a rare example of
solution for several hours. It has a well-resolved X-band a stable germanium derivative that contains a paramagnetic
EPR spectrum with gi = 2.0022 in toluene at ambient tem- ligand. Until now, only a few examples were known. The
perature (Figure 1). The hyperfine structure arises from hy- stable paramagnetic germylene based on the 1,2-bis(aryl-
perfine coupling (HFC) of an unpaired electron with mag- imino)acenaphthene radical anion has been obtained by
netic nuclei 1H (99.98%, I = 1/2, µN = 2.7928), 14N Fedushkin and co-workers.[1h] Stable mono- and diradical
(99.63%, I = 1, µN = 0.4037), 35Cl (75.77%, I = 3/2, µN
=
germanium(IV) complexes reported in papers[5b,5c] contain
0.8218) and 37Cl (24.23%, I = 3/2, µN = 0.6841).[7] The the tridentate 3,5-di-tert-butyl-1,2-quinone-1-(2-hydroxy-
splitting parameters are: Ai(21H) = 2.1 G, Ai(214N) = 2.9 G, 3,5-di-tert-butylphenyl)imine anion. There are some reports
Ai(35Cl) = 1.3 G, Ai(37Cl) = 1.1 G. The observation of HFC about the formation of stable germanium derivatives with
with two nitrogen and two hydrogen atoms indicates radical the radical anion of 3,6-di-tert-butyl-o-benzoquinone;
centre delocalization over two ligands. This interligand elec- however, these compounds were not isolated as solids but
1
tron exchange is also confirmed by 14N- and H-HFC con- were only established in solutions by EPR spectros-
stants, which are nearly twice lower than those for the copy.[5d,5e] Moreover, different radical derivatives from the
(ISQ)SnPh2Cl complex.[4] The character of the EPR spec- reaction of elemental germanium with 3,5-di-tert-butyl-o-
trum for (AP)(ISQ)GeCl stays unchanged in the tempera- benzoquinone were postulated in ref.,[5f] but structures as-
ture interval 220–300 K.
signed for some of them are not incontrovertible.
Scheme 8.
Eur. J. Inorg. Chem. 2008, 1435–1444
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
1437

A. V. Piskunov et al.
FULL PAPER
Molecular Structures of 1, 3, 4 and 5
Molecular structures of 1, 3, 5 and 4 are shown in Fig-
ures 2, 3, 4 and 5, respectively. Selected bond lengths and
angles are given in Table 1. The crystal data collection and
structure refinement data are listed in Table 2. Crystals suit-
able for X-ray analysis were obtained from hexane for 1
and 3, a 2:1 mixture of hexane/dichloromethane for 4 and
acetone for 5.
Figure 4. PLATON[20] presentation of molecule 5. H atoms are
omitted for clarity.
Figure 2. PLATON[20] presentation of molecule 1. (A) H atoms and
methyl groups of isopropyl substituents are omitted for clarity. (B)
H atoms and tert-butyl substituents are omitted for clarity.
Figure 5. PLATON[20] presentation of molecule 4. H atoms and
methyl groups of isopropyl and tert-butyl substituents are omitted
for clarity.
The central germanium atom in 1 (Figure 2) is coordi-
nated to two nitrogen and two oxygen atoms of o-amido-
phenolato ligands in a distorted tetrahedral geometry. The
dihedral angle between the two chelate rings is 85.74(4)°.
The angle O(1)–Ge(1)–O(2) [108.36(4)°] is notably less than
the angle N(1)–Ge(1)–N(2) [126.96(5)°] because of the ste-
ric repulsion of N-aryl groups.
The distances Ge–O [1.786(1) and 1.785(1) Å] and Ge–
N [1.798(1) and 1.800(1) Å] are nearly equal. They are no-
ticeably shorter than sums of covalent radii of germanium
and oxygen and of germanium and nitrogen (1.88 and
1.93 Å respectively),[7] and are similar to those observed for
GeIV complexes simultaneously containing O- and N-
bonded ligands (1.789–1.828 and 1.742–1.820 Å corre-
spondingly).[2c,8]
Figure 3. PLATON[20] presentation of molecule 3. H atoms are
omitted for clarity.
1438
www.eurjic.org
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2008, 1435–1444

Ge Complexes with Iminobenzoquinone Ligands in Different Redox States
Table 1. Selected bond lengths [Å] and angles [°] for complexes 1 and 3–5.
Bond lengths
1
3
4
5
1st mol (A)
2nd mol (B)
Ge(1)–O(1)
Ge(1)–O(2)
Ge(1)–N(1)
Ge(1)–N(2)
O(1)–C(1)
O(2)–C(27)
N(1)–C(2)
N(1)–C(15)
N(2)–C(28)
N(2)–C(41)
C(1)–C(6)
1.786(1)
1.785(1)
1.800(1)
1.798(1)
1.384(2)
1.387(2)
1.421(2)
1.434(2)
1.419(2)
1.438(2)
1.390(2)
1.405(2)
1.383(2)
1.400(2)
1.389(2)
1.404(2)
1.396(2)
1.400(2)
1.381(2)
1.391(2)
1.395(2)
1.399(2)
–
1.807(1)
1.816(1)
1.840(2)
2.136(2)
1.385(2)
1.363(2)
1.409(2)
1.432(2)
1.465(2)
1.473(2)
1.394(3)
1.395(2)
1.387(3)
1.401(3)
1.382(3)
1.403(3)
1.415(3)
1.384(3)
1.384(3)
1.376(3)
1.400(3)
1.387(3)
2.182(1)
–
1.785(3)
–
3.261(5)
–
1.395(5)
–
1.420(5)
1.448(5)
1.874(1)
1.870(1)
1.884(1)
1.887(1)
1.339(2)
1.340(2)
1.368(2)
1.448(2)
1.377(2)
1.440(2)
1.406(3)
1.419(3)
1.402(2)
1.377(3)
1.415(3)
1.393(2)
1.404(3)
1.418(2)
1.398(2)
1.390(3)
1.407(3)
1.388(2)
2.174(1)
–
1.880(1)
1.880(1)
1.879(1)
1.879(1)
1.335(2)
1.335(2)
1.377(2)
1.442(2)
1.377(2)
1.442(2)
1.396(2)
1.437(2)
1.391(2)
1.382(2)
1.415(3)
1.392(2)
1.396(2)
1.437(2)
1.391(2)
1.382(2)
1.415(3)
1.392(2)
2.158(1)
–
–
–
1.396(5)
1.407(6)
1.390(6)
1.389(6)
1.395(6)
1.396(6)
–
–
–
–
–
–
C(1)–C(2)
C(2)–C(3)
C(3)–C(4)
C(4)–C(5)
C(5)–C(6)
C(27)–C(32)
C(27)–C(28)
C(28)–C(29)
C(29)–C(30)
C(30)–C(31)
C(31)–C(32)
Ge(1)–Cl(1)
Ge(1)–C(27)
Ge(1)–C(33)
Ge(1)–C(39)
–
–
–
–
1.950(4)
1.935(4)
1.954(4)
–
–
–
–
–
–
Angles
O(2)–Ge(1)–O(1)
O(2)–Ge(1)–N(2)
O(1)–Ge(1)–N(2)
O(2)–Ge(1)–N(1)
O(1)–Ge(1)–N(1)
N(2)–Ge(1)–N(1)
C(1)–O(1)–Ge(1)
C(27)–O(2)–Ge(1)
C(2)–N(1)–C(15)
C(2)–N(1)–Ge(1)
C(15)–N(1)–Ge(1)
C(28)–N(2)–C(41)
C(28)–N(2)–Ge(1)
C(41)–N(2)–Ge(1)
O(1)–Ge(1)–Cl(1)
O(2)–Ge(1)–Cl(1)
N(1)–Ge(1)–Cl(1)
N(2)–Ge(1)–Cl(1)
O(1)–Ge(1)–C(33)
O(1)–Ge(1)–C(27)
C(33)–Ge(1)–C(27)
O(1)–Ge(1)–C(39)
C(33)–Ge(1)–C(39)
C(27)–Ge(1)–C(39)
108.36(4)
92.56(5)
118.51(5)
118.89(4)
92.31(5)
126.96(5)
109.25(8)
108.71(7)
120.71(11)
108.06(9)
130.41(9)
119.95(11)
107.63(8)
131.87(9)
–
–
–
–
–
–
–
–
–
–
148.92(6)
83.48(6)
82.26(6)
95.79(6)
88.79(6)
160.53(7)
111.29(11)
117.05(11)
121.60(15)
110.13(12)
127.95(12)
114.29(14)
105.46(10)
125.36(11)
105.26(4)
102.00(4)
109.85(5)
89.24(4)
–
–
–
–
–
171.49(4)
85.28(5)
90.87(5)
91.32(6)
85.39(6)
130.42(5)
112.71(11)
112.72(11)
120.29(13)
112.43(11)
127.28(11)
119.43(12)
111.87(11)
128.32(11)
94.38(3)
94.13(3)
114.14(3)
115.44(4)
–
172.30(7)
85.52(5)
91.27(5)
91.27(5)
85.51(5)
130.67(8)
112.91(10)
112.91(10)
121.25(11)
112.54(10)
125.98(10)
121.25(11)
112.54(10)
125.98(10)
93.85(3)
93.85(3)
114.67(4)
114.67(4)
–
57.59(6)
–
120.5(2)
–
112.9(3)
80.64(6)
165.44(9)
–
–
–
–
–
–
–
108.73(14)
106.30(14)
115.36(16)
108.71(15)
111.67(15)
105.77(17)
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
C–O bond lengths [1.384(2) and 1.387(2) Å] are typical 1H NMR spectrum, the compound can be described as a
for analogous (o-amidophenolato)tin complexes (1.351– complex containing a GeIV core bonded with two o-amido-
1.400 Å),[3,4] and C–N distances [1.421(2) and 1.419(2) Å] phenolato ligands.
are slightly longer than those in similar Sn derivatives
As can be seen from its molecular structure (Figure 2B),
(1.398–1.408 Å).[3,4] At the same time, C–O and C–N bond complex 1 contains two nonequivalent pairs of isopropyl
1
lengths are significantly longer than those in the o-imino- substituents. The H NMR spectrum of 1 in [D8]toluene
semiquinonate tin(IV) complex [1.298(4) and 1.334(4) Å contains two signals attributed to CH groups and four sig-
respectively].[4]
nals to the iPr CH3 groups, indicating that the above-men-
Hence, also taking into account that a toluene solution tioned nonequivalence caused by steric hindrances to free
of compound 1 is EPR-silent and has a rather well-resolved rotation of Ph(iPr)2 substituents remains in solution.
Eur. J. Inorg. Chem. 2008, 1435–1444
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
1439

A. V. Piskunov et al.
FULL PAPER
Table 2. Summary of crystal and refinement data for the complexes.
Complex
1
3·hexane
4
5
Empirical formula
Formula weight
Temperature [K]
Wavelength [Å]
Crystal system
Space group
C52H74GeN2O2
831.72
100(2)
0.71073
monoclinic
P21/n
C58H89ClGeN2O2
954.35
100(2)
0.71073
monoclinic
P21/n
C44H38F15GeNO
954.34
100(2)
C52H74ClGeN2O2
867.17
100(2)
0.71073
monoclinic
C2/c
0.71073
triclinic
¯
P1
Unit cell dimensions
a [Å]
b [Å]
c [Å]
α [°]
12.3194(4)
21.1575(7)
19.383(7)
13.7975(6)
17.6923(7)
22.9534(9)
10.4360(14)
10.7926(15)
20.423(3)
104.359(2)
91.794(2)
107.108(2)
2116.2(5)
2
40.1711(11)
18.4703(5)
24.8586(7)
β [°]
106.3360(10)
98.7990(10)
126.2130(10)
γ [°]
Volume [Å3]
4849.5(3)
4
5537.2(4)
4
14881.4(7)
12
Z
Density (calculated) [gcm–3]
Absorption coefficient [mm–1]
Crystal size [mm3]
θ range for data collection [°]
Reflections collected
Independent reflections
Completeness to θ = 25.00
Absorption correction
1.139
0.670
0.35ϫ0.15ϫ0.06
1.93–26.00
41235
1.145
0.642
0.24ϫ0.18ϫ0.14
1.89–25.00
30273
1.498
0.825
0.63ϫ0.48ϫ0.25
2.03–29.18
21637
1.161
0.710
0.40ϫ0.37ϫ0.06
2.03–26.00
63179
9518 [R(int) = 0.0406] 9721 [R(int) = 0.0387] 10956 [R(int) = 0.0281] 14583 [R(int) = 0.0643]
100.0%
semiempirical from
equivalents
99.6%
semiempirical from
equivalents
95.8%
semiempirical from
equivalents
99.7%
semiempirical from
equivalents
Max. and min. transmission
Refinement method
0.9609 and 0.7992
full-matrix least-
squares on F2
9518/0/810
R1 = 0.0392,
wR2 = 0.0978
R1 = 0.0504,
wR2 = 0.1024
1.044
0.9155 and 0.8612
full-matrix least-
squares on F2
9721/41/877
R1 = 0.0472,
wR2 = 0.1235
R1 = 0.0665,
wR2 = 0.1322
1.035
0.8202 and 0.6243
full-matrix least-
squares on F2
10956/6/593
R1 = 0.0879,
wR2 = 0.2287
R1 = 0.0925,
wR2 = 0.2304
1.158
0.9586 and 0.7643
full-matrix least-
squares on F2
14583/14/1193
R1 = 0.0445,
wR2 = 0.0983
R1 = 0.0780,
wR2 = 0.1084
1.000
Data/restraints/parameters
Final R indices
[IϾ2σ(I)][a,b]
R indices
(all data)
Goodness-of-fit on F2[c]
Largest diff. peak and hole [eÅ–3] 0.576 and –0.288
1.253 and –0.506
1.343 and –0.937
0.787 and –0.365
2 2
2
[a] R = ∑||Fo| – |Fc||/∑|Fo|. [b] ωR = R(ωF2) = {∑[ω(Fo2–Fc ) ]/∑[ω(Fo2)2]}1/2; ω = 1/[σ2(Fo2)+(aP)2+bP], P = [2Fc +max(Fo,0)]/3. [c] S =
Goof = {∑ [ω(Fo2–Fc ) ]/(n–p)}1/2, where n is the number of reflections, and p is the number of refined parameters.
2 2
The pentacoordinated Ge atom in complex 3 has a dis- olato)germanium complex (AP)2Ge. The carbon ring
torted square-pyramidal environment (Figure 3). The imQ C(1)C(6) also has aromatic character with an average C–C
ligands form the base of the pyramid, and the chlorine distance of 1.394Ϯ0.015 Å.
atom occupies an apical site. Notably, Cl(1) is shifted from
The second ligand shows the remarkable features of a
the N(1) towards the N(2) atom in the hypothetical plane protonated o-aminophenolato ligand. While the N(1) atom
N(1)Cl(1)Ge(1)N(2) [the sum of bond angles N(1)–Ge(1)– is three-coordinate (sp2 hybridized) with a nearly planar ge-
Cl(1), N(2)–Ge(1)–Cl(1) and N(1)–Ge(1)–N(2) is ometry, the N(2) atom is protonated and sp3 hybridized.
359.62(16)°]: the angles N(1)–Ge(1)–Cl(1) and N(2)–Ge(1)– Additionally, the N(2)–C(28) [1.465(2) Å] bond is signifi-
Cl(1) are 109.85(5)° and 89.24(4)° respectively. Apparently, cantly elongated in comparison with that in compound 1,
this distortion is determined by intramolecular Cl(1)···H(2) and it is typical for those in o-aminophenolato transition-
interaction. The Cl(1)···H(2) distance is 2.59(3) Å, which is metal complexes (1.46–1.47 Å).[10a,10b] The distances O(2)–
significantly less than the sum of the van der Waals radii C(27) and O(1)–C(1) [1.363(5) and 1.385(2) Å, respectively]
(2.97 Å).[9] The heteroatom-to-germanium-to-heteroatom lie in the range that is usual for phenolates (1.35–
angles reveal the difference, which is unusual for five-coor- 1.39 Å).[10a–10d,f,11] All C–C bond lengths of the C(27)C(32)
dinate complexes of the ML2X type (L is an o-iminobenzo- ring, with an average value of 1.391 Å, are similar to those
quinonato-based ligand): the value of the angle O(1)– in the C(1)C(6) aromatic ring.
Ge(1)–O(2) [148.92(6)°] is less than that for N(1)–Ge(1)–
The Ge(1)–O(1) and Ge(1)–O(2) covalent bonds
N(2) [160.53(7)°], while in transition-metal complexes [1.807(1) and 1.816(1) Å respectively] are quite close in
M(ISQ)2Hal (M = Co, Fe, Mn) a decrease in the N–M–N length; at the same time the Ge(1)–N(1) bond is consider-
angle relative to O–M–O is usual.[10f]
ably shorter than Ge(1)–N(2) [1.840(2) and 2.136(2) Å cor-
The first organic ligand is the dianion o-amidophenolate. respondingly] as a result of the donor-acceptor nature of
The distances O(1)–C(1) of 1.385(2) Å and N(1)–C(2) of the Ge(1)–N(2) bond in contrast to the covalent bond
1.409(2) Å are close to the distances in the bis(o-amidophen- Ge(1)–N(1).
1440
www.eurjic.org
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2008, 1435–1444

Ge Complexes with Iminobenzoquinone Ligands in Different Redox States
The Ge(1)–Cl(1) distance [2.182(1) Å] is nearly identical orbital (MO) for both ligands with the formation of a delo-
to the sum of the covalent radii of chlorine and germanium calized valent state for the ligands. Additional evidence for
(2.18 Å).[7]
this statement is the temperature-independent EPR spec-
Thus, complex 3 contains the o-amidophenolato dianion trum of complex 5, which indicates delocalization of the
and o-aminophenolato anion ligands chelating the germani- unpaired electron over two o-iminoquinonato ligands. A
um(IV) chloride moiety.
spin- and dipole-allowed LLCT (ligand-to-ligand charge
There are two crystallographically independent mole- transfer) between the group MOs of these ligands probably
cules of complex (AP)(ISQ)GeCl (5) in the unit cell, one of corresponds to the low-energy band (2300 nm) in NIR
which is in the common position (A), whereas the other is spectrum.
disposed on the C2 axis (B). Both molecules can be consid-
The molecule in the crystal of complex 4 contains a tetra-
ered as distorted square pyramids with organic ligands in hedral germanium atom coordinated with three perfluo-
the base, as in compound 3. The chlorine atom also occu- rophenyl groups and a nonchelating O-coordinated o-ami-
pies an apical site (Figure 4).
nophenolato ligand (Figure 5). There is no bonding be-
The bond of Ge to the apical chlorine atom for the tween the Ge(1) and N(1) atoms [the Ge(1)···N(1) distance
second (symmetrical) molecule, Ge(1)–Cl(1) [2.1579(6) Å], is 3.261(5) Å].
is shorter than the same bond in the first (unsymmetrical)
The six-membered carbon ring C(1)C(6) is undoubtedly
molecule, Ge(2)–Cl(2), [2.1741(4) Å].
aromatic with an average C–C bond length of
The bond angles O–Ge–O and N–Ge–N in both mole- 1.396Ϯ0.008 Å. The O(1)–C(1) distance [1.395(5) Å] is typ-
cules are nearly equal: O(1A)–Ge(1A)–O(2A) is 171.49(4)° ical for phenolato ligands, the N(1)–C(2) bond length is
and O(1B)–Ge(2B)–O(1BЈ) is 172.30(7)°; N(1A)–Ge(1A)– 1.420(5) Å – this is significantly shorter than the same type
N(2A) is 130.42(5)° and N(3B)–Ge(2B)–N(3BЈ) is of bond, N(1)–C(28) [1.465(2) Å]. The length of the germa-
130.67(8)°.
nium-to-oxygen bond Ge(1)–O(1) is close to Ge–O bonds
We did not find a significant difference in the geometrical in the four-coordinate (AP)2Ge and typical for covalent
characteristics of the ISQ and AP ligands in 5. Comparison GeIV–O bonds.
of the geometrical parameters of these ligands in known
As mentioned above, steric factors play an important role
derivatives[4,10] with the ones in 5 shows that the C–O and in obtaining GeIV derivatives from GeII. Therefore, it is of
C–N bond lengths in 5 have intermediate values between interest to estimate quantitatively the steric factors in the
the analogous distances in ISQ and AP ligands of other complexes investigated. For this purpose, we shall use a
known derivatives. The O(1)–C(1) and N(1)–C(2) bond model of the ligand solid angles, which allows to calculate
lengths for the first ligand [1.339(2) and 1.368(2) Å respec- the saturation of the coordinating sphere of the metal by
tively] are quite close to the O(2)–C(27) and N(2)–C(28) ligands.[12] Our calculation for complexes 1 and 3–5 shows
distances [1.340(2) and 1.377(2) Å respectively] for the sec- that the saturations of the coordinating sphere of germa-
ond one. They are longer than the corresponding bond nium are 92.6(2), 95.0(2), 96.5(2) and 96.2(2)%, respec-
lengths in o-iminobenzosemiquinonato complexes (1.29– tively. It should be noted that the given values are very high
1.32 and 1.33–1.36 Å)[4,10] and slightly shorter than those in comparison with analogous characteristics for lanthanide
in o-amidophenolates (C–O 1.35–1.36 Å, C–N 1.38– complexes [85.6(5)–89.6(2)%].[13] Besides, the reason why
1.39 Å).[4,10] It should be noted that the six-membered car- thf does not coordinate germanium in 1 but coordinates
bon rings C(1)C(6) and C(27)C(32) are quite distorted. The the central atom in bis(o-amidophenolato) derivative
quinoid pattern is observed for both ligands: two shorter (AP)2Sn(thf)[3] becomes obvious as a result of this calcula-
bonds are separated by longer bonds (Table 1).
The Ge(1)–O(1) [1.874(1) Å] and
tion. The saturation of the coordinating sphere in (AP)2-
Ge(1)–N(1) Sn(thf)[3] without the thf molecule is 79.9(2)%; that is sig-
[1.884(1) Å] distances are close to the Ge(1)–O(2) nificantly less than that in 1 [92.6(2)%]. The coordination
[1.870(1) Å] and Ge(1)–N(2) [1.887(1) Å] distances and of the thf molecule in the (AP)2Sn(thf) complex increases
longer in comparison with Ge–O and Ge–N bonds in 1. the saturation of the coordinating sphere up to 94.7(2)%,
Chelate angles O(1)–Ge(1)–N(1) of 85.39(6)° and O(2)– which is close to the analogous value in 1. Thus, the steric
Ge(1)–N(2) of 85.28(5)° are less than corresponding angles size of the thf molecule is approximately equal to 14%.
in 1.
Complex 1 does not have 14% free space in the coordinat-
The second crystallographically independent molecule ing sphere of the germanium atom. Therefore, we can con-
has a C2 axis along the Ge–Cl bond, and both ligands are clude that nonbonding ligand–ligand interactions in the co-
equal each to other. The resulting geometrical characteris- ordinating sphere of 1 prevent the coordination of the thf
tics of the ligands are also intermediate between the dianion molecule.
o-amidophenolate and the radical anion o-iminobenzose-
miquinolate: the O–C bonds are 1.335(2) Å and the N–C
bonds are 1.377(2) Å; the carbon ring also shows a quinoid-
type of distortion.
Conclusions
The crystal structure of 5 indicates a charge distribution
In the present paper we have shown that bulky aryl-sub-
of (ISQ)(AP)GeCl. The structural equivalence of ligands stituted o-iminoquinone can serve as a versatile ligand that
can be explained by the presence of an overall molecular can be used to synthesize both divalent and tetravalent ger-
Eur. J. Inorg. Chem. 2008, 1435–1444
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
1441

A. V. Piskunov et al.
FULL PAPER
(0.46 g, 2 mmol) in thf (10 mL). The reaction mixture turned
orange immediately; thf was evacuated, the residue was addition-
ally dried in vacuo at 80 °C and distilled at 120 °C (5ϫ10–3 mm) to
manium amidophenolate derivatives. At the same time, the
ligand itself can be transformed into the dianion, radical
anion or protonated anion forms. It is noteworthy that in-
troduction of two iminoquinone-based ligands into the co-
ordination environment of the germanium atom in homo-
ligand complexes leads to bis(o-amidophenolato)germani-
um(IV) independently of the initial redox state of the imi-
noquinone.
1
give a red viscous resin. Yield: 0.74 g, 1.6 mmol, 81.8%. H NMR
(200 MHz, C7D8, 25 °C): δ = 0.92 (d, JH,H = 6.9 Hz, 6 H, CH3 of
iPr), 0.97 (d, JH,H = 6.9 Hz, 6 H, CH3 of iPr), 1.27 (s, 9 H, tBu),
1.73 (s, 9 H, tBu), 2.65 (sept., JH,H = 6.9 Hz, 2 H, CH of iPr), 6.45
(d, JH,H = 2.1 Hz, 1 H, CH-aromatic), 7.10–7.20 (m, 3 H, CH-
aromatic), 7.24 (d, JH,H = 2.1 Hz, 1 H, CH-aromatic) ppm. IR
(Nujol): ν = 1594 (w), 1575 (m), 1412 (m), 1378 (m), 1363 (w), 1331
˜
(m), 1302 (m), 1257 (w), 1240 (m), 1220 (w), 1203 (w), 1179 (w),
1164 (w), 1115 (w), 1103 (w), 1056 (w), 1041 (w), 1028 (w), 994 (s),
968 (w), 936 (m), 911 (w), 886 (w), 860 (m), 822 (w), 802 (s), 769
(m), 742 (w), 721 (s), 699 (w), 658 (w), 620 (w), 594 (m), 556 (m),
525 (m), 508 (w), 462 (w), 425 (w) cm–1. C26H37GeNO (452.22):
calcd. C 69.05, H 8.25, Ge 16.06; found C 68.99, H 8.25, Ge 16.10.
Experimental Section
General Remarks: All reactants were reagent grade. Solvents were
purified by following standard methods.[14] 4,6-di-tert-butyl-N-(2,6-
diisopropylphenyl)-o-iminobenzoquinone (imQ)[15] and tris-(per-
fluorophenyl)germane[16] were prepared according to known pro-
cedures. All manipulations on complexes were performed in vacuo
under conditions in which oxygen and moisture were excluded.
The infrared spectra of the complexes in the 4000–400 cm–1 range
were recorded in Nujol with a Specord M-80 spectrophotometer.
NMR spectra were recorded in C7D8 (1, 2), C6D6 (3) or CDCl3 (4)
solution by using a “Bruker DPX-200” instrument with Me4Si as
internal standard.
Reaction of imQ with 2: The initially wine-red o-iminoquinone
(imQ) (0.76 g, 2 mmol) suspension in thf (20 mL) was added to
(o-amidophenolato)germanium(II) (2) (0.9 g, 2 mmol) in the same
solvent (20 mL). The reaction mixture turned colourless. The prod-
uct was recrystallized from n-hexane and identified as compound
1 by its 1H NMR spectrum and melting point. Yield: 1.12 g,
1.35 mmol, 67.3%.
The EPR spectrum of 5 was recorded with a Bruker ER 200 D-
SRC spectrometer with an ER041 MR microwave bridge, ER 4105
DR double resonator and ER 4111 VT variable temperature unit.
The gi values were determined by using diphenylpicrylhydrazyl as
the reference (gi = 2.0037). HFC constants were obtained by simu-
lation with the WinEPR SimFonia Software (Bruker).
(AP)(APH)GeCl (3): Bis(o-amidophenolato)germanium(IV) (1)
(0.83 g, 1 mmol) was dissolved in thf (20 mL) and exposed to anhy-
drous HCl obtained in a separate ampoule from NaCl (0.058 g,
1 mmol) and H2SO4 (1 mL). When gas evolution stopped, the thf
solution was frozen to condense gaseous HCl, the ampoule was
closed, and the solution was warmed. While warming, the reaction
mixture turned brown, thf was evaporated and the residue was
recrystallized from n-hexane. Complex 3 was obtained as light-
brown, nearly colourless crystals. Yield: 0.52 g, 0.545 mmol, 54.5%;
(AP)2Ge (1): A solution of the o-amidophenolatolithium deriva-
tive[4] (0.8 g, 2 mmol) in hexane or thf (20 mL) was added to GeCl4
(0.2 g, 1 mmol) in the same solvent (10 mL), and after that the
reaction mixture turned colourless. The thf was evaporated, and
the residue was redissolved in n-hexane and filtered. Compound 1
was obtained as colourless, air-sensitive crystals from the cooling
1
m.p. 205 °C. H NMR (200 MHz, C6D6, 25 °C): δ = 0.61 (d, JH,H
= 6.7 Hz, 3 H, CH3 of iPr), 1.04 (s, 9 H, tBu), 1.13 (d, JH,H
=
6.7 Hz, 3 H, CH3 of iPr), 1.18 (d, JH,H = 6.7 Hz, 3 H, CH3 of iPr),
1.19 (d, JH,H = 6.7 Hz, 6 H, CH3 of iPr), 1.19 (s, 9 H, tBu), 1.20
(s, 9 H, tBu), 1.33 (d, JH,H = 6.7 Hz, 3 H, CH3 of iPr), 1.35 (d,
JH,H = 6.7 Hz, 3 H, CH3 of iPr), 1.45 (s, 9 H, tBu), 1.56 (d, JH,H
= 6.7 Hz, 3 H, CH3 of iPr), 2.78 (sept., JH,H = 6.7 Hz, 1 H, CH of
iPr), 3.32 (sept., JH,H = 6.7 Hz, 1 H, CH of iPr), 3.38 (sept., JH,H
= 6.7 Hz, 1 H, CH of iPr), 3.94 (sept., JH,H = 6.7 Hz, 1 H, CH of
1
hexane solution. Yield: 0.63 g, 0.76 mmol, 75.7%; m.p. 305 °C. H
NMR (200 MHz, C7D8, 25 °C): δ = 0.16 (br. s, 6 H, CH3 of iPr),
0.88 (br. s, 6 H, CH3 of iPr), 1.14 (br. s, 6 H, CH3 of iPr), 1.22 (s,
18 H, tBu), 1.28 (br. s, 6 H, CH3 of iPr), 1.63 (s, 18 H, tBu), 2.63
(br. s, 2 H, CH of iPr), 3.83 (br. s, 2 H, CH of iPr), 6.29 (d, JH,H
= 2.2 Hz, 2 H, CH-aromatic), 6.88–7.19 (m, 6 H, CH-aromatic),
7.08 (d, JH,H = 2.2 Hz, 1 H, CH-aromatic) ppm. IR (Nujol): ν =
˜
iPr), 6.44 (d, JH,H = 2.2 Hz, 1 H, CH-aromatic), 6.65 (d, JH,H =
1583 (s), 1447 (w), 1413 (s), 1362 (m), 1330 (s), 1287 (m), 1268 (w),
1229 (m), 1209 (vs), 1178 (w), 1160 (w), 1113 (m), 1103 (m), 1053
(w), 1042 (w), 1026 (w), 985 (vs), 966 (s), 932 (w), 911 (w), 859 (m),
821 (s), 804 (s), 774 (w), 757 (s), 739 (w), 671 (w), 656 (w), 603 (m),
567 (m), 524 (w), 509 (w), 471 (w), 437 (m) cm–1. C52H74GeN2O2
(831.80): calcd. C 75.09, H 8.97, Ge 8.73; found C 75.02, H 8.97,
Ge 8.76.
2.0 Hz, 1 H, CH-aromatic), 6.96 (d, JH,H = 2.2 Hz, 1 H, CH-aro-
matic), 7.08 (s, 1 H, NH), 7.11–7.19 (m, 2 H, CH-aromatic), 7.32
(d, JH,H = 2.0 Hz, 1 H, CH-aromatic), 7.25–7.44 19 (m, 4 H, CH-
aromatic) ppm; assignment of NMR signals was defined more ex-
actly by using 2D COSY NMR spectroscopy. IR (Nujol): ν = 3262
˜
(s), 1579 (s), 1445 (w), 1416 (s), 1362 (m), 1334 (m), 1302 (w), 1292
(m), 1268 (w), 1251 (s), 1233 (m), 1211 (s), 1172 (m), 1118 (m),
1102 (w), 1052 (w), 1042 (m), 1028 (w), 967 (s), 966 (w), 942 (w),
931 (w), 911 (w), 877 (m), 846 (vs), 831 (w), 819 (w), 801 (m), 792
(w), 766 (w), 757 (s), 733 (m), 711 (w), 684 (w), 658 (m), 648 (w),
605 (m), 682 (m), 562 (w), 538 (w), 525 (w), 514 (w), 462 (w), 444
(w), 428 (m), 405 (w) cm–1. C58H89ClGeN2O2 (954.43): calcd. C
72.99, H 9.40, Cl 3.71, Ge 7.61; found C 72.77, H 9.56, Cl 3.84,
Ge 7.65.
Reaction of GeCl2·Dioxane with Lithium o-Iminosemiquinonate: A
solution of the o-amidophenolatolithium complex[4] (0.8 g, 2 mmol)
in toluene (20 mL) was treated with an equimolar quantity of imQ
(0.76 g, 2 mmol) in the same solvent (20 mL). The reaction mixture
turned dark blue, indicating the formation of the (o-iminosemiqui-
nonato)lithium derivative. It was then added to GeCl2·dioxane
(0.46 g, 2 mmol) in toluene (10 mL), and the colour of the radical
anion complex disappeared immediately. The product was sepa-
rated from lithium chloride by filtration, recrystallized from n-hex-
(APH)GeIV(C6F5)3 (4): The wine-red suspension of imQ (1 g,
2.6 mmol) in thf (20 mL) was added to a (C6F5)3GeH (0.63 g,
2.6 mmol) solution in the same solvent (10 mL). The colour of the
reaction mixture changed to light brown. The solvent was evapo-
rated, and the residue was recrystallized from a n-hexane/CH2Cl2
mixture as white air-stable crystals of 4 Yield: 1.41 g, 2.26 mmol,
1
ane and identified as compound 1 by its H NMR spectrum and
melting point. Yield: 0.91 g, 1.1 mmol, 55.0%.
(AP)Ge (2): A solution of the o-amidophenolatolithium deriva-
tive[4] (0.8 g, 2 mmol) in thf (20 mL) was added to GeCl2·dioxane
1442
www.eurjic.org
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2008, 1435–1444

Ge Complexes with Iminobenzoquinone Ligands in Different Redox States
1
Tumanskii, P. Pine, Y. Apeloig, N. J. Hill, R. West, J. Am.
Chem. Soc. 2004, 126, 7786–7787; e) G. A. Abakumov, V. K.
Cherkasov, A. V. Piskunov, N. O. Druzhkov, Dokl. Chem. 2004,
399, 223–225; f) A. V. Piskunov, I. A. Aivaz’yan, V. K. Cherka-
sov, G. A. Abakumov, J. Organomet. Chem. 2006, 691, 1531–
1534; g) O. Kühl, Coord. Chem. Rev. 2004, 248, 411–427; h)
I. L. Fedushkin, N. M. Khvoinova, A. Yu. Baurin, G. K. Fu-
kin, V. K. Cherkasov, M. P. Bubnov, Inorg. Chem. 2004, 43,
7807–7815; i) B. Tumanskii, P. Pine, Y. Apeloig, N. J. Hill, R.
West, J. Am. Chem. Soc. 2005, 127, 8248–8249; j) G. A. Abaku-
mov, V. K. Cherkasov, A. V. Piskunov, I. A. Aivaz’yan, N. O.
Druzhkov, Dokl. Chem. 2005, 404, 189–192; k) I. L. Fedushkin,
A. A. Skatova, V. A. Chudakova, N. M. Khvoinova, A. Yu.
Baurin, S. Dechert, M. Hummert, H. Schumann, Organometal-
lics 2004, 23, 3714–3718.
86.9%; m.p. 213 °C. H NMR (200 MHz, CDCl3, 25 °C): δ = 0.85
(d, JH,H = 6.8 Hz, 6 H, CH3 of iPr), 0.99 (s, 9 H, tBu), 1.05 (d,
JH,H = 6.8 Hz, 6 H, CH3 of iPr), 1.25 (s, 9 H, tBu), 2.80 (sept.,
JH,H = 6.8 Hz, 2 H, CH of iPr), 5.63 (s, 1 H, NH), 5.80 (d, JH,H
2.2 Hz, 1 H, CH-aromatic), 6.65 (d, JH,H = 2.2 Hz, 1 H, CH-aro-
matic), 7.05–7.24 (m, 3 H, CH-aromatic) ppm. IR (Nujol): ν =
3386 (s), 1646 (s), 1597 (w), 1580 (m), 1519 (s), 1415 (m), 1384 (s),
1309 (m), 1290 (s), 1243 (w), 1221 (m), 1204 (m), 1183 (m), 1161
(m), 1147 (w), 1109 (m), 1086 (vs), 1017 (m), 976 (vs), 936 (m), 914
(w), 888 (w), 862 (m), 833 (s), 802 (m), 771 (m), 748 (vs), 684 (w),
651 (w), 620 (s), 601 (w), 585 (w), 572 (w), 532 (w), 501 (m), 460
(m) cm–1. C44H38F15GeNO (954.39): calcd. C 55.37, H 4.01, F
29.86, Ge 7.61; found C 55.29, H 3.99, F 29.87, Ge 7.65.
=
˜
(AP)(ISQ)GeCl (5): Aminophenolate 3 (0.5 g, 0.6 mmol) was dis-
solved in acetone (15 mL), and the solution was placed in open air.
The colour of reaction mixture slowly turned to dark green. Dark
crystals of 5 formed as the solvent evaporated. Yield: 0.29 g,
[2]
a) A. Arndt, H. Schäfer, W. Saak, M. Weidenbruch, Z. Anorg.
Allg. Chem. 2005, 631, 1341–1342; b) M. Weidenbruch, M.
Stürmann, H. Kilian, S. Pohl, W. Saak, Chem. Ber./Recueil
1997, 130, 735–738; c) A. Naka, N. J. Hill, R. West, Organome-
tallics 2004, 23, 6330–6332; d) R. West, D. F. Moser, I. A. Gu-
zei, G.-H. Lee, A. Naka, W. Li, A. Zabula, S. Bukalov, L. Le-
ites, Organometallics 2006, 25, 2709–2711; e) J. Pfeiffer, W. Ma-
ringgele, M. Noltemeyer, A. Meller, Chem. Ber. 1989, 122, 245–
252; f) A. V. Zabula, F. E. Hahn, T. Pape, A. Hepp, Organome-
tallics 2007, 26, 1972–1980.
A. V. Piskunov, I. A. Aivaz’yan, G. K. Fukin, E. V. Baranov,
A. S. Shavyrin, V. K. Cherkasov, G. A. Abakumov, Inorg.
Chem. Commun. 2006, 9, 612–615.
A. V. Piskunov, I. A. Aivaz’yan, G. A. Abakumov, V. K. Cher-
kasov, O. V. Kuznetsova, G. K. Fukin, E. V. Baranov, Russ.
Chem. Bull. 2007, 56, 261–266.
a) P. Rivière, A. Castel, J. Satgé, D. Guyot, J. Organomet.
Chem. 1986, 315, 157–164; b) H. B. Stegmann, K. Scheffler, F.
Stöcker, Angew. Chem. Int. Ed. Engl. 1971, 10, 499–500; c) S.
Bruni, A. Caneschi, F. Cariati, C. Delfs, A. Dei, D. Gatteschi,
J. Am. Chem. Soc. 1994, 116, 1388–1394; d) G. A. Abakumov,
V. K. Cherkasov, N. I. Ermolaev, V. I. Nevodchikov, L. G.
Abakumova, Russ. Chem. Bull. 1995, 44, 1508–1512; e) T. I.
Prokof’eva, A. I. Prokof’ev, N. N. Bubnov, S. P. Solodovnikov,
V. V. Ershov, M. I. Kabachnik, Khim. Fiz. 1984, 3, 25–31; f)
A. A. El-Hadad, B. R. McGarvey, B. Merzougui, R. G. W.
Sung, A. K. Trikha, D. G. Tuck, J. Chem. Soc., Dalton Trans.
2001, 1046–1052.
J. C. D. Brand, G. Eglinton, Application of Spectroscopy to Or-
ganic Chemistry, Oldbourne press, London, 1965, 140 pp.
J. Emsley, The Elements, Clarendon Press, Oxford, 1991,
251 pp.
A. C. Gottfried, J. Wang, E. E. Wilson, L. W. Beck, M. M. B.
Holl, J. W. Kampf, Inorg. Chem. 2004, 43, 7665–7670.
Yu. V. Zefirov, P. M. Zorky, Russ. Chem. Rev. 1995, 64, 415–
428.
0.35 mmol, 58.5%; m.p. 244 °C. IR (Nujol): ν = 1719 (w), 1640
˜
(m), 1573 (s), 1522 (w), 1447 (s), 1420 (w), 1361 (m), 1338 (w), 1322
(w), 1291 (m), 1257 (w), 1242 (w), 1223 (w), 1201 (m), 1169 (m),
1103 (m), 1057 (w), 1041 (w), 1030 (w), 998 (s), 935 (w), 912 (w),
894 (w), 855 (m), 829 (m), 802 (s), 771 (m), 757 (w), 727 (m), 706
(w), 685 (w), 654 (w), 611 (w), 600 (w), 557 (w), 541 (w), 528 (w),
508 (w), 433 (w) cm–1. NIR (Nujol): ca. 2300 nm.
C52H74ClGeN2O2 (867.25): calcd. C 72.02, H 8.60, Cl 4.09, Ge
8.38; found C 71.97, H 8.58, Cl 4.12, Ge 8.42.
[3]
[4]
[5]
X-ray Crystallographic Study of 1, 3, 4 and 5: Intensity data for 1,
3, 4 and 5 were collected at 100 K with a Smart Apex dif-
fractometer with graphite monochromated Mo-Kα radiation (λ =
0.71073 Å) in the φ-ω scan mode (ω = 0.3°, 10 s on each frame).
The intensity data were integrated by the SAINT program.[17]
SADABS[18] was used to perform area-detector scaling and absorp-
tion corrections. The structures of 1 and 3 were solved by the Pat-
terson method and those of 4 and 5 were solved by direct methods
and were refined on F2 by using all reflections with the SHELXTL
package.[19] All non-hydrogen atoms were refined anisotropically.
The hydrogen atoms of complexes 1, 3 (except H atoms in the solv-
ate hexane molecule) and 5 (except the H atoms for one tert-butyl
group) were found from Fourier synthesis and refined isotropically.
Hydrogen atoms in 4 were placed in calculated positions and re-
fined in the “riding-model” [Uiso(H) = 1.5Ueq(C) in CH3 groups
and Uiso(H) = 1.2Ueq(C) in other ligands]. In complex 4 one of the
tBu groups is disordered in two positions. Selected bond lengths
and angles for 1, 3, 4 and 5 are given in Table 1. Table 2 summarizes
the crystal data and some details of data collection and refinement
for these complexes.
[6]
[7]
[8]
[9]
[10]
a) H. Chun, C. N. Verani, P. Chaudhuri, E. Bothe, E. Bill, T.
Weyhermüller, K. Wieghardt, Inorg. Chem. 2001, 40, 4157–
4166; b) H. Chun, P. Chaudhuri, T. Weyhermüller, K. Wiegh-
ardt, Inorg. Chem. 2002, 41, 790–795; c) G. A. Abakumov, A. I.
Poddel’sky, M. P. Bubnov, G. K. Fukin, L. G. Abakumova,
V. N. Ikorskii, V. K. Cherkasov, Inorg. Chim. Acta 2005, 358,
3829–3840; d) G. A. Abakumov, V. K. Cherkasov, A. I. Pod-
del’sky, M. P. Bubnov, L. G. Abakumova, G. K. Fukin, Dokl.
Chem. 2004, 399, 207–210; e) A. I. Poddel’sky, V. K. Cherkasov,
G. K. Fukin, M. P. Bubnov, L. G. Abakumova, G. A. Abaku-
mov, Inorg. Chim. Acta 2004, 357, 3632–3640; f) G. A. Abaku-
mov, V. K. Cherkasov, M. P. Bubnov, L. G. Abakumova, V. N.
Ikorskii, G. V. Romanenko, A. I. Poddel’sky, Russ. Chem. Bull.
2006, 55, 44–52.
CCDC-645244, 661897, 661898, 661899 contain the supplementary
crystallographic data for this paper. These data can be obtained
free of charge from The Cambridge Crystallographic Data Centre
via www.ccdc.cam.ac.uk/data_request/cif.
Acknowledgments
We are grateful to the Russian Foundation for Basic Research
(07-03-00819-a, 06-03-32728-a), Russian President Grant
(4947.2006.3, 8752.2006.3) and Russian Science Support Founda-
tion for financial support of this work.
[11]
a) C. G. Pierpont, Coord. Chem. Rev. 2001, 219–221, 415–433
and references cited therein; b) C. G. Pierpont, R. M. Bu-
chanan, Coord. Chem. Rev. 1981, 38, 45–87; c) J. M. Clemente,
C. Wong, P. Bhattacharyya, A. M. Z. Slawin, D. J. Williams,
J. D. Woollins, Polyhedron 1994, 13, 261–266; d) X. Sun, H.
[1] a) N. J. Hill, R. West, J. Organomet. Chem. 2004, 689, 4165–
4183; b) T. Gans-Eichler, D. Gudat, M. Nieger, Angew. Chem.
Int. Ed. 2002, 41, 1888–1891; c) T. Gans-Eichler, D. Gudat, K.
Nattinen, M. Nieger, Chem. Eur. J. 2006, 12, 1162–1173; d) B.
Eur. J. Inorg. Chem. 2008, 1435–1444
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
1443

A. V. Piskunov et al.
FULL PAPER
Chun, K. Hildenbrand, E. Bothe, T. Weyhermüller, F. Neese,
K. Wieghardt, Inorg. Chem. 2002, 41, 4295–4303.
[12] I. A. Guzei, M. Wendt, Dalton Trans. 2006, 3991–3999.
[13] G. K. Fukin, I. A. Guzei, E. V. Baranov, J. Coord. Chem. 2007,
60, 937–944.
[14] D. D. Perrin, W. L. F. Armarego, D. R. Perrin, Purification of
Laboratory Chemicals, Pergamon Press, Oxford, 1980, 391 pp.
[15] G. A. Abakumov, N. O. Druzhkov, Yu. A. Kurskii, A. S. Shav-
yrin, Russ. Chem. Bull. 2003, 52, 712–717.
[17] Bruker, SAINTPLUS Data Reduction and Correction Program
v.6.02a, Bruker AXS, Madison, WI, USA, 2000.
[18] G. M. Sheldrick, SADABS v.2.01, Bruker/Siemens Area Detec-
tor Absorption Correction Program, Bruker AXS, Madison,
WI, USA, 1998.
[19] G. M. Sheldrick, SHELXTL v.6.12, Structure Determination
Software Suite, Bruker AXS, Madison, WI, USA, 2000.
[20] A. L. Spek, PLATON A Multipurpose Crystallographic Tool,
Utrecht University: Utrecht, The Netherlands, 2000.
Received: October 16, 2007
[16] M. N. Bochkarev, G. A. Razuvaev, N. S. Vyazankin, Russ.
Chem. Bull. 1975, 8, 1701–1705.
Published Online: February 5, 2008
1444
www.eurjic.org
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2008, 1435–1444