Divalent germanium compound with a radical-anionic ligand: Molecular structures of (dpp-BIAN)asterisk inside a circle sign-GeCl and its hydrochloration products (2) and (3) (see abstract). (dpp-BIAN = 1,2-bis{(2,6-diisopropylphenyl)imino}acenaphthene)

Article abstract of DOI:10.1021/ic048801g

The germanium(II) compound (dpp-BIAN)GeCl (1), which contains the radical anion of dpp-BIAN can be prepared either by reacting free dpp-BIAN ligand with 2 equiv of GeCl₂(1,4-dioxane) in Et₂O or by metathetical reaction of the sodium salt of dpp-BIAN with germanium dichloride in Et ₂O or benzene. The reaction of benzene solutions of 1 with 2 or 3 equiv of HCl led to protonation of the dpp-BIAN ligand affording [(dpp-BIAN)(H)₂]^{asterisk inside a circle sign+}[GeCl ₃]^- (2) and [{(dpp-BIAN)(H)2 ^{asterisk inside a circle sign+}}₂(Cl^-)] ⁺[GeCl₃]^- (3), which incorporate the radical cation of the protonated ligand. Compounds 1-3 have been characterized by elemental analysis, IR, UV-vis, and electron spin resonance (ESR) spectroscopy. Molecular structures of 1-3 were determined by single-crystal X-ray diffraction. In molecule 1, the Ge atom is positioned at the apex of the slightly distorted trigonal pyramid. The Ge-N bond lengths in 1 are 2.0058(19) and 2.004(2) A. The molecular structure of 2 consists of contact ions [(dpp-BIAN)(H)₂]⁺ and [GeCl₃]^-. In the molecular structure of 3, two radical cations of [(dpp-BIAN)(H) ₂]⁺ are coordinated by the chlorine anion. The ESR signal of 1 indicates the presence of a dpp-BIAN radical anion and shows a hyperfine structure due to the coupling of an unpaired electron to ¹⁴N, ⁷³Ge, ³⁵Cl, ³⁷Cl, and ¹H nuclei (A_N = 0.48 (2 N), A_Ge = 0.96, A _Cl = 0.78 (³⁵Cl), A_Cl = 0.65 (³⁷Cl), A_H = 0.11 (4 H) mT, g = 2.0014). Both 2 and 3 reveal ESR signals of radical cation [(dpp-BIAN)(H)₂] ^{asterisk inside a circle sign+} (septet, A_N = 0.53, A _H = 0.48 mT, g = 2.0031).

Full text of DOI:10.1021/ic048801g

Inorg. Chem. 2004, 43, 7807−7815
Divalent Germanium Compound with a Radical-Anionic Ligand:
•-
Molecular Structures of (dpp-BIAN) GeCl and Its Hydrochloration
•+
-
Products [(dpp-BIAN)(H)2] [GeCl3] and
•+
- +
-
[
{
(dpp-BIAN)(H)2
}
2(Cl )] [GeCl3] (dpp-BIAN
)
1,2-Bis (2,6-diisopropylphenyl)imino
{
}
acenaphthene)
Igor L. Fedushkin,* Natalie M. Khvoinova, Andrey Yu. Baurin, Georgii K. Fukin,
Vladimir K. Cherkasov, and Mikhail P. Bubnov
G. A. RazuVaeV Institute of Organometallic Chemistry, Russian Academy of Sciences,
Tropinina 49, 603950 Nizhny NoVgorod, GSP-445, Russia
Received August 30, 2004
The germanium(II) compound (dpp-BIAN)GeCl (1), which contains the radical anion of dpp-BIAN can be prepared
either by reacting free dpp-BIAN ligand with 2 equiv of GeCl2(1,4-dioxane) in Et2O or by metathetical reaction of
the sodium salt of dpp-BIAN with germanium dichloride in Et2O or benzene. The reaction of benzene solutions of
1 with 2 or 3 equiv of HCl led to protonation of the dpp-BIAN ligand affording [(dpp-BIAN)(H)2]•+[GeCl3]- (2) and
•+
[
{
(dpp-BIAN)(H)2
}
2(Cl-)]+[GeCl3]- (3), which incorporate the radical cation of the protonated ligand. Compounds
1
−
3 have been characterized by elemental analysis, IR, UV
Molecular structures of 1 3 were determined by single-crystal X-ray diffraction. In molecule 1, the Ge atom is
positioned at the apex of the slightly distorted trigonal pyramid. The Ge N bond lengths in 1 are 2.0058(19) and
−vis, and electron spin resonance (ESR) spectroscopy.
−
−
2.004(2) Å. The molecular structure of 2 consists of contact ions [(dpp-BIAN)(H)2]+ and [GeCl3]-. In the molec-
ular structure of 3, two radical cations of [(dpp-BIAN)(H)2]+ are “coordinated” by the chlorine anion. The ESR sig-
nal of 1 indicates the presence of a dpp-BIAN radical anion and shows a hyperfine structure due to the cou-
1
pling of an unpaired electron to 14N, 73Ge, 35Cl, 37Cl, and H nuclei (AN
) 0.48 (2 N), AGe ) 0.96, ACl )
0.78 (35Cl),
ACl
)
0.65 (37Cl), AH
)
0.11 (4 H) mT, g
) 2.0014). Both 2 and 3 reveal ESR signals of radical cation
0.53, AH 0.48 mT, g
[(dpp-BIAN)(H)2]•+ (septet, AN
)
)
)
2.0031).
Introduction
toward organic substrates showed that these might be useful
reagents for organic synthesis.3e-g The group 3 metal
complex (dpp-BIAN)GaCl2 with the radical-anionic ligand
has been reported by Jones et al.4 Recently, we succeeded
in isolation of stable germylenes derived from three different
Ar-BIAN ligands (e.g., (dpp-BIAN)Ge, (dtb-BIAN)Ge, and
(dph-BIAN)Ge (Chart 1)).5
The present work is a part of our recently initiated research
on the main group metal complexes of 1,2-bis(arylimino)-
acenaphthene ligands (Ar-BIAN). Within the past decade,
transition-metal complexes of these rigid bidentate ligands
were studied intensively because of a wide range of applica-
tions in catalytic reactions.1 The non-transition-metal com-
plexes of the neutral ligand of type [(dpp-BIAN)(MCl2)]+-
[MCl4]- (dpp-BIAN ) 1,2-bis{(2,6-diisopropylphenyl)-
imino}acenaphthene, M ) B, Ga) were first reported in
2002.2 One year later, we described a series of alkaline and
alkaline-earth metal complexes with different anionic forms
(1) (a) van Laren, M. W.; Elsevier, C. J. Angew. Chem., Int. Ed. 1999,
38, 3715-3717. (b) Grasa, G. A.; Singh, R.; Stevens, E. D.; Nolan,
S. P. J. Organomet. Chem. 2003, 687, 269-279. (c) Heumann, A.;
Giordano, L.; Tenaglia, A. Tetrahedron Lett. 2003, 44, 1515-1518.
(d) Cherian, A. E.; Lobkovsky, E. B.; Coates, G. W. Chem. Commun.
2003, 2566-2567. (e) Al-Abaidi, F.; Ye, Z.; Zhu, S. Macromol. Chem.
Phys. 2003, 204, 1653-1659. (f) Fassina, V.; Ramminger, C.; Seferin,
M.; Mauler, R. S.; de Souza, R. F.; Monteiro, A. L. Macromol. Rapid
Comm. 2003, 24, 667-670. (f) Leatherman, M. D.; Svejda, S. A.;
Johnson, L. K.; Brookhart, M. J. Am. Chem. Soc. 2003, 125, 3068-
3081. (g) Takeuchi, D.; Yasuda, A.; Osakada, K. J. Chem. Soc., Dalton
Trans. 2003, 2029-2035. (h) Kiesewetter, J., Kaminsky, W. Chem.s
Eur. J. 2003, 9, 1750-1758.
of dpp-BIAN (e.g., M+ (dpp-BIAN)n- (M ) Li, Na;
n
n ) 1-4)3a,b and M2+(dpp-BIAN)2- (M ) Mg, Ca)).3c,d The
study of reactivity of dpp-BIAN-Mg and -Ca complexes
* Author to whom correspondence should be addressed. E-mail:
igorfed@imoc.sinn.ru.
10.1021/ic048801g CCC: $27.50
Published on Web 11/02/2004
© 2004 American Chemical Society
Inorganic Chemistry, Vol. 43, No. 24, 2004 7807

Fedushkin et al.
Chart 1
in a number of reactions involving oxidation, addition, and
insertion reactions.6e,7e,g,h Different experimental (X-ray dif-
fraction, NMR, and photoelectron spectroscopy) and com-
putational methods (B3LYP) were applied for understanding
these three-coordinate germanium(II) compounds. Despite
this extensive research in the field of Ge(II) complexes with
N-based ligands, to date there are no examples of unambigu-
ously characterized heteroleptic Ge(II) compounds con-
taining paramagnetic ligands. Bearing in mind that elec-
tron spin resonance (ESR) spectroscopic data on the para-
magnetic species (L)•-Ge2+X- may give new insight into
the electronic structure of the three-coordinate Ge(II) com-
pounds, we started preparation of a Ge(II) derivative with a
dpp-BIAN radical-anionic ligand.
In this article, we report on the synthesis and crystal
structure of (dpp-BIAN)•-GeCl as well as its spectroscopic
characterization by means of ESR, IR, and electron absorp-
tion spectroscopy. We also describe the formation of the
radical cation [(dpp-BIAN)(H)2]•+ from radical anion
(dpp-BIAN)• - under protonation of (dpp-BIAN)•-GeCl with
HCl.
Ligands with nitrogen donors play an important role in
the increasing development of the chemistry of germanium
in the oxidation state +2.6,7 Until now, the following types
of such compounds were described in the literature: the
imidazogermoline-2-yliden,6a its benzo-,6b pyrido-,6c naph-
tho-,6d and tropo-annulated6e analogues. A variety of ger-
manium(II) compounds supported by ketiminate ligands has
been reported as well.7 A review article on the ketiminate
metal complexes appeared recently.8
Heteroleptic complexes of the type (L)-Ge2+X- (L )
tropo- or ketiminate; X- ) F, Cl, I, RO, Me, CF3SO3, N3)
contain N-ligands in their chelating monoanionic form.7
These compounds represent both fundamental and practical
interests. They have been recognized as promising reagents
Results and Discussion
(2) Jenkins, H. A.; Dumaresque, C. L.; Vidovic, D.; Clyburne, J. A. C.
Can. J. Chem. 2002, 80, 1398-1403.
Synthesis and Molecular Structure of Compounds 1-3.
The germanium(II) compound (dpp-BIAN)GeCl (1), which
contains the radical anion of dpp-BIAN, can be prepared in
two different ways: (1) by reacting free dpp-BIAN ligand
with 2 equiv of GeCl2(1,4-dioxane) in diethyl ether or (2)
by metathetical reaction of the sodium salt of dpp-BIAN
with germanium dichloride either in Et2O or benzene
(Scheme 1).
In the reaction of GeCl2(1,4-dioxane) with free dpp-BIAN,
germanium dichloride acts as reducing agent toward the
diimine ligand. Our preliminary study showed that the
reduction potential of dpp-BIAN radical anion in tetrahy-
drofuran (THF) equals -1.5 V versus a saturated calomel
electrode. Besides 1, this redox reaction produces a second
product, which crystallizes from the reaction mixture together
with 1 in the form of colorless crystals. Although this
byproduct was not identified, the absence of signals in its
1H NMR spectrum and the stoichiometry of 1 allowed
suggesting that this second product is hexachlorodigermane.
Compound 1 crystallizes from either benzene or Et2O as
deep red crystals. An exposure of the reaction mixture formed
from the reaction of GeCl2(1,4-dioxane) with free dpp-BIAN
to air caused a color change from cherry red to deep green.
As shown below, this color change reflects the formation of
the protonated radical cation of dpp-BIAN.
The reaction of benzene solutions of 1 formed during the
course of the metathetical reaction with 2 or 3 equiv of HCl
affords compounds 2 and 3, respectively (Scheme 2).
Compounds 2 and 3 crystallized from benzene as deep green
crystals. In crystalline form, these compounds are relatively
stable to air and show no sign of decomposition within a
few days. Compounds 1-3 have been characterized by
elemental analysis, IR, UV-vis, and ESR spectroscopy.
Molecular structures of 1-3 were determined by single-
crystal X-ray diffraction. The crystallographic data for 1-3
(3) (a) Fedushkin, I. L.; Skatova, A. A.; Chudakova, V. A.; Fukin, G. K.
Angew. Chem., Int. Ed. 2003, 42, 3294-3298. (b) Fedushkin, I. L.;
Skatova, A. A.; Chudakova, V. A.; Cherkasov, V. K.; Chudakova, V.
A.; Fukin, G. K.; Lopatin, M. A. Eur. J. Inorg. Chem. 2004, 388-
393. (c) Fedushkin, I. L.; Skatova, A. A.; Chudakova, V. A.; Fukin,
G. K.; Dechert, S.; Schumann, H. Eur. J. Inorg. Chem. 2003, 3336-
3346. (d) Fedushkin, I. L.; Chudakova, V. A.; Skatova, A. A.;
Khvoinova, N. M.; Kurskii, Yu. A.; Glukhova, T. A.; Fukin, G. K.;
Dechert, S.; Hummert, M.; Schumann, H. Z. Anorg. Allg. Chem. 2004,
630, 501-507. (e) Fedushkin, I. L.; Skatova, A. A.; Cherkasov, V.
K.; Chudakova, V. A.; Dechert, S.; Hummert, M.; Schumann, H.
Chem.sEur. J. 2003, 9, 5778-5783. (f) Fedushkin, I. L.; Khvoinova,
N. M.; Skatova, A. A.; Fukin, G. K. Angew. Chem., Int. Ed. 2003,
42, 5223-5226. (g) Fedushkin, I. L.; Skatova, A. A.; Lukoyanov, A.
N.; Chudakova, V. A.; Dechert, S.; Hummert, M.; Schumann, H. Russ.
Chem. Bull. In press.
(4) Baker, R. J.; Jones, C.; Kloth, M.; Mills, D. P. New J. Chem. 2004,
28, 207-213.
(5) Fedushkin, I. L.; Skatova, A. A.; Chudakova, V. A.; Khvoinova, N.
M.; Baurin, A. Yu.; Dechert, S.; Hummert, M.; Schumann, H.
Organometallics 2004, 23, 3714-3718.
(6) (a) Herrmann, W. A.; Denk, M.; Behm, J.; Scherer, W.; Klingan, F.
R.; Bock, H.; Solouki, B.; Wagner, M. Angew. Chem., Int. Ed. 1992,
31, 1485-1488. (b) Pfeiffer, J.; Maringgele, W.; Noltemeyer, M.;
Meller, A. Chem. Ber. 1989, 122, 245-252. (c) Ku¨hl, O.; Lo¨nnecke,
P.; Heinicke, J. Polyhedron 2001, 20, 2215-2222. (d) Bazinet, P.;
Yap, G. P. A.; Richeson, D. S. J. Am. Chem. Soc. 2001, 123, 11162-
11167. (e) Dias, H. V. R.; Wang, Z. J. Am. Chem. Soc. 1997, 119,
4650-4655.
(7) (a) Ayers, A. E.; Klapo¨tke, T. M.; Dias, H. V. R. Inorg. Chem. 2001,
40, 1000-1005. (b) Stender, M.; Phillips, A. D.; Power, P. P. Inorg.
Chem. 2001, 40, 5314-5315. (c) Ding, Y.; Roesky, H. W.; Noltem-
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1190-1194. (d) Ding, Y.; Hao, H.; Roesky, H. W.; Noltemeyer, M.;
Schmidt, H. G. Organometallics 2001, 20, 4806-4811. (e) Akkari,
A.; Byrne, J. J.; Saur, I.; Rima, G.; Gornitzka, H.; Barrau, J. J.
Organomet. Chem. 2001, 622, 190-198. (f) Ding, Y.; Ma, Q.; Roesky,
H. W.; Herbst-Irmer, R.; Uso´n, I.; Noltemeyer, M.; Schmidt, G.
Organometallics 2002, 21, 5216-5220. (g) Ding, Y.; Ma, Q.; Uso´n,
I.; Roesky, H. W.; Noltemeyer, M.; Schmidt, G. J. Am. Chem. Soc.
2002, 124, 8542-8543. (h) Saur, I.; Rima, G.; Gornitzka, H.; Miqueu,
K.; Barrau, J. Organometallics 2003, 22, 1106-1109. (i) Saur, I.;
Rima, G.; Miqueu, K.; Gornitzka, H.; Barrau, J. J. Organomet. Chem.
2003, 672, 77-85. (j) Saur, I.; Miqueu, K.; Rima, G.; Barrau, J.;
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7808 Inorganic Chemistry, Vol. 43, No. 24, 2004

DiWalent Germanium with a Radical-Anionic Ligand
Scheme 1
Scheme 2
Table 1. Crystal Data and Structure Refinement Details for 1, 2, and 3
compound
1
2
3
empirical formula
fw
C36H40ClGeN2
608.74
C36H41Cl3GeN2
680.65
C87H99Cl4GeN4
1415.09
temperature, K
crystal system
space group
100(2)
monoclinic
P21/c
120(2)
orthorhombic
P212121
100(2)
monoclinic
P21/n
unit cell dimensions Å, degree
a ) 10.4153(12)
b ) 19.789(2)
c ) 15.8871(19)
â ) 105.369(2)
3157.4(6)
4
1.281
1.081
1276
0.15 × 0.15 × 0.08
1.68 to 24.99
16 457
5564 (R(int) ) 0.0282)
5564/9/514
1.060
a ) 10.131(3)
b ) 13.696(2)
c ) 22.431(5)
R ) â ) γ ) 90
3419.6(13)
4
1.322
1.157
1416
0.17 × 0.15 × 0.04
1.74 to 23.31
16 088
4934 (R(int) ) 0.0417)
4934/9/543
0.972
a ) 21.3305(12)
b ) 15.6716(9)
c ) 24.0119(13)
â ) 99.0300(10)
7927.3(8)
volume, Å3
Z
4
density (calc), Mg/m3
absorption coefficient, mm-1
F(000)
1.186
0.567
2996
crystal size, mm3
0.30 × 0.25 × 0.20
1.56 to 24.00
39 209
12 440 (R(int) ) 0.0304)
12 440/11/1209
1.020
θ range for data collection, deg
reflections collected
independent reflections (I > 2σ(I))
data/restraints/parameters
goodness of fit on F2
final R indices (I > 2σ(I))a
R1 ) 0.0416
wR2 ) 0.1074
R1 ) 0.0326
wR2 ) 0.0713
R1 ) 0.0441
wR2 ) 0.1067
2
2
2
2
2
2
a R ) ∑||Fo| - |Fc||/ ∑|Fo|, wR ) R(wF2) ) {∑[w(Fo - Fc )2]/∑[w(Fo )2]}1/2; w ) 1/[σ2(Fo ) + (aP)2 + bP], P ) [2Fc + Fo ]/3.
are listed in Table 1. The molecular structures of 1, 2, and
3 are depicted in Figures 1, 2, and 3, respectively. Selected
bond distances and angles for 1-3, together with geometrical
parameters for the two-coordinate germanium(II) complex
of dianionic dpp-BIAN ligand, (dpp-BIAN)Ge,5 three-
coordinate tropo-R-diketiminate [1,2-C7H5(NiPr)2]GeCl,6e and
â-diketiminate [CH{C(Me)NPh}2]GeCl,7h are presented in
Table 2. Compound 1 crystallizes in the monoclinic space
group P21/c with four molecules in the unit cell. The main
bond lengths and angles in 1 can be compared with those of
(dpp-BIAN)Ge5 and three-coordinate Ge(II) complexes with
chelating N-based ligands (e.g., ketiminates [1,2-C7H5-
(NiPr)2]GeCl,6e [1,2-C7H5(NMe)2]GeCl,6e [CH{C(Me)N-
(Mes)}2]GeCl,7a and [CH{C(Me)NPh}2]GeCl7h). In mole-
cule 1 (Figure 1), as well as in all three-coordinate species
mentioned above, the germanium atom is positioned at the
apex of the slightly distorted trigonal pyramid.
The sum of the bond angles around the germanium atom
(N(2)-Ge(1)-N(1), 81.57(8)°; N(2)-Ge(1)-Cl(1), 98.63-
(6)°; N(1)-Ge(1)-Cl(1), 96.64(6)°) is 276.8°, slightly
exceeds the value expected for ideal pyramidal geometry
(270°), and is significantly smaller than values for tetrahedral
Inorganic Chemistry, Vol. 43, No. 24, 2004 7809

Fedushkin et al.
Table 2. Selected Bond Lengths (Å) and Angles (deg) for 1, 2, 3, (dpp-BIAN)Ge, [1,2-C7H5(NiPr)2]GeCl, and [CH{C(Me)NPh}2]GeCl
compound
1
2
3
(dpp-BIAN)Gea
[1,2-C7H5(NiPr)2]GeClb
[CH{C(Me)NPh}2]GeClc
Bond Lengths
Ge-N(1)
2.0058(19)
2.004(2)
2.2693(8)
1.896(3)
1.885(3)
1.956(4)
1.956(4)
2.368(2)
1.955(2)
1.965(1)
2.340(6)
Ge-N(2)
Ge-Cl(1)
2.3385(7)
2.3128(7)
2.2462(8)
1.344(2)
1.326(2)
2.2830(8)
2.2789(8)
2.3161(7)
1.329(3)
1.333(3)
1.330(3)
1.330(3)
0.87(2)
Ge-Cl(2)
Ge-Cl(3)
N(1)-C(1)
N(2)-C(2)
N(3)-C(37)
N(4)-C(38)
N(1)-H(1)
N(2)-H(2)
N(3)-H(3)
N(4)-H(4)
C(1)-C(2)
C(37)-C(38)
1.326(3)
1.329(3)
1.374(4)
1.370(4)
1.341(6)d
1.341(6)d
1.337(2)d
1.338(2)d
0.82(2)
0.90(2)
0.89(2)
0.88(2)
0.88(2)
1.442(3)
1.439(3)
1.421(3)
81.57(8)
1.447(3)
1.381(5)
Bond Angles
85.20(12)
N(1)-Ge-N(2)
Cl(1)-Ge-Cl(2)
Cl(2)-Ge-Cl(3)
Cl(1)-Ge-Cl(3)
N(1)-Ge-Cl(1)
N(2)-Ge-Cl(1)
80.3(2)
90.28(6)
92.75(3)
96.28(3)
94.86(3)
97.92(3)
96.78(3)
96.29(3)
96.64(6)
98.63(6)
96.6(1)
96.6(1)
93.55(5)
94.95(4)
a Reference 5. b Reference 6e. c Reference 7h. d C-imino metallacycle.
of the sp2 orbital in two-coordinate N-based germylenes (e.g.,
imidazogermoline-2-yliden,6a its benzo-,6b pyrido-,6c and
naphtho-annulated6d analogues). This assumption is supported
by the fact that two-coordinate N-based germylenes can act
as donor ligands toward transition-metal centers (for in-
6d
stance, Ni[Ge{C10H6(NiPr)2}]4 and (CO)3Mo[Ge{C2H2-
t
9
(NCH2 Bu)2}]3 ) and the lack of examples for such com-
plexation in three-coordinate Ge(II) species. Because of the
weaker bonding between the Ge cation and the dpp-BIAN
radical anion compared to that of the dpp-BIAN dianion,
the Ge-N bond lengths in 1 (2.0058(19) and 2.004(2) Å)
are remarkably longer than those in (dpp-BIAN)Ge (1.896-
(3) and 1.885(3) Å).5 The Ge-N distances in 1 are longer
than the mean distances in tropo-R-diketiminate [1,2-C7H5-
(NiPr)2]GeCl (both 1.956(4) Å)6e and â-diketiminate
[CH{C(Me)NPh}2]GeCl (1.955(2) and 1.965(1) Å).7h As a
result, the bite angle N-Ge-N in 1 (81.57(8)°) is smaller
than that in (dpp-BIAN)Ge (85.20(12)°),5 1,3,2-diazager-
moline-2-ylidene C2H2[N(CH2 Bu)]2Ge (87.75(6)°),6c and
t
â-diketiminate [CH{C(Me)NPh}2]GeCl (90.28(6)°)7h but
close to the bite angle in tropo-R-diketiminate [1,2-C7H5-
(NiPr)2]GeCl (80.3(2)°).6e Comparison of the N-C and C-C
bond distances within the metallacycle -GeN(1)C(1)-
C(2)N(2)- in 1 with those in (dpp-BIAN)Ge5 and free ligand
dpp-BIAN10 confirms the radical anionic character of dpp-
BIAN in 1. Thus, N-C distances in 1 (N(1)-C(1) 1.326-
(3), N(2)-C(2) 1.329(3) Å) are elongated compared to the
free ligand (both N-C 1.282(4) Å)10 but notably shorter than
related distances in (dpp-BIAN)Ge (N(1)-C(1) 1.374(4),
N(2)-C(2) 1.370(3) Å).5 The C-C distance within the
metallacycle in 1 (C(1)-C(2) 1.421(3) Å) is shortened
compared to free dpp-BIAN ligand (C(1)-C(2) 1.534(6) Å)10
but is longer than that in (dpp-BIAN)Ge (C(1)-C(2) 1.381-
Figure 1. Molecular structure of 1. Thermal ellipsoids are of 30%
probability.
(328°) and trigonal-planar (360°) environments. The angle
between the Ge-Cl bond and the N(1)-Ge(1)-N(2) plane
is 101.6(1)°. The electronic structure of the pyramidal
geometry of these three-coordinate species may be indicative
of high s character of the Ge lone pair orbital. In general,
the basicity of this orbital is assumed to be lower than that
(9) Ku¨hl, O.; Lo¨nnecke, P.; Heinicke, J. Inorg. Chem. 2003, 42, 2836-
2838.
(10) Fedushkin, I. L.; Chudakova, V. A.; Fukin, G. K.; Dechert, S.;
Hummert, M.; Schumann, H. Russ. Chem. Bull. In press.
7810 Inorganic Chemistry, Vol. 43, No. 24, 2004

DiWalent Germanium with a Radical-Anionic Ligand
in Ge-Cl bond lengths in 2 might be attributed to a weak
interaction of the chlorine atoms Cl(1) and Cl(2) with
hydrogen atoms H(1) and H(2), which were localized at
distances of 0.88(2) and 0.90(2) Å from nitrogen atoms N(1)
and N(2), respectively. The intramolecular Cl(1)‚‚‚N(2)
(3.236(2) Å) and Cl(1)‚‚‚H(2) (2.44(2) Å) distances indicate
the bonding interactions Cl‚‚‚N (3.23 Å)13 and Cl‚‚‚H (2.67
Å).13 The protonation of 1 with 2 equiv HCl converted the
dpp-BIAN radical anion into radical cation [(dpp-BIAN)-
(H)2]•+. Because the protonation occurs by adding H+ to N
lone pairs, as expected no changes in the diimine skeleton
are observed. C-N and C-C distances in the diimine part
of molecule 2 (N(1)-C(1) 1.344(2), N(2)-C(2) 1.326(2),
C(1)-C(2) 1.447(3) Å) are very similar to those in complex
1 (vide supra, Table 2).
In the molecular structure of 3, two radical cations [(dpp-
BIAN)(H)2]+ are “coordinated” by the chlorine anion Cl(4)
(Figure 3, the lattice benzene molecules omitted). The
[GeCl3]- anion weakly interacts with hydrogen atoms of the
naphthalene system of one of the radical-cationic ligands (two
shortest contacts are 2.856 and 2.926 Å). As seen by
Ge-Cl bond angles (Table 2), the geometry of the [GeCl3]-
anion is slightly less pyramidalized compared to that in 2.
Besides, the difference between Ge-Cl distances in 3
(Ge-Cl(1) 2.2830(8), Ge-Cl(2) 2.2789(8), and Ge-Cl(3)
2.3161(7) Å) is less pronounced. Four atoms H(1), H(2),
H(3), and H(4) were found at distances of 0.87(2), 0.89(2),
0.88(2), and 0.88(2) Å from nitrogen atoms N(1), N(2),
N(3), and N(4), respectively. The distances between atoms
H(1), H(2), H(3), H(4), N(1), N(2), N(3), N(4), and the
chlorine anion Cl(4) are influenced by specific interactions
H‚‚‚Cl and N‚‚‚Cl (Cl(4)‚‚‚H(1-4) 2.27(2)-2.32(2) Å,
Cl(4)‚‚‚N(1-4) 3.132(2)-3.178(2) Å). Interaction between
atoms H(1), H(2), H(3), and H(4) and chlorine anion
Cl(4) is indicated by short H‚‚‚Cl distances (Cl(4)‚‚‚H(1)
2.29(2), Cl(4)‚‚‚H(2) 2.28(2), Cl(4)‚‚‚H(3) 2.32(2), and
Cl(4)‚‚‚H(4) 2.27(2) Å). Repulsion between the isopropyl
groups of the two radical cations is minimized by ligand
twist of 41°, thus causing a staggered conformation of the
ligands (Figure 4).
Figure 2. Molecular structure of 2. Thermal ellipsoids are of 30%
probability.
(5) Å).5 These observations are in an agreement with the
symmetry of the ligand lowest unoccupied molecular orbital
(LUMO). Its population should cause the shortening of the
C(1)-C(2) bond and elongation of the C-N bonds. One-
electron reduction of dpp-BIAN is supposed to lead to bond
alternation, which lies between those of (dpp-BIAN)2- and
(dpp-BIAN)0.
Compounds 2 and 3 crystallize each with four molecules
in the unit cells in the orthorhombic and monoclinic space
groups P212121 and P21/n, respectively. The molecular
structure of 2 consists of contact ions [(dpp-BIAN)(H)2]+
and [GeCl3]- (Figure 2). Similar to structure 1, the germa-
nium atom in the [GeCl3]- anion adopts pyramidal geometry
with Cl-Ge-Cl angles of 92.75(3), 96.28(3), and 94.86-
(3)°. In the anion, two Ge-Cl distances (Ge-Cl(1) 2.3385-
(7) and Ge-Cl(2) 2.3128(7) Å) are notably longer than the
third one (Ge-Cl(3) 2.2462(8) Å). However, the average
Ge-Cl distance in [GeCl3]- (2.299 Å) is close to those found
in other structurally characterized [GeCl3]- anions (e.g.,
[D3CND3]+[GeCl3]- (2.327 Å),11a [{Me2Pz}3Ge2]+[GeCl3]-
(2.311 Å),11b [Me2N-(CH2C5H4)Fe(C5H5)]+[GeCl3]- (2.281
Å))11c and to the calculated value (2.309 Å).12 The difference
ESR Spectroscopic Studies 1-3. The presence of a
dpp-BIAN radical anion in 1 is confirmed by observation
of an ESR signal in toluene solution. This signal is
moderately resolved at 285 K and shows a hyperfine structure
due to coupling of the unpaired electron to 14N, 73Ge, 35Cl,
37Cl, and 1H nuclei (hyperfine coupling (HFC) constants: AN
) 0.48 (2 N), AGe ) 0.96, ACl ) 0.78 (35Cl), ACl ) 0.65
(37Cl), AH ) 0.11 (4 H) mT, g ) 2.0014, Figure 5).
A decrease in the temperature to 230 K caused insignifi-
cant changes in the spectrum. To the best of our knowledge,
this is the first ESR spectroscopic characterization of a
crystallographically authenticated Ge(II) species.
(11) (a) Yamada, A.; Mikawa, K.; Okuda, T.; Knight, K. S. J. Chem. Soc.,
Dalton Trans. 2002, 2112-2118. (b) Steiner, A.; Stalke, D. Inorg.
Chem. 1995, 34, 4846-4853. (c) Hosmane, N. S.; Yang, J.; Lu, K.-
J.; Zhang H.; Siriwardane, U.; Islam, M. S.; Thomas, J. L. C.; Maguiri,
J. A. Organometallics 1998, 17, 2784.
Tuck and co-workers reported the observation of an ESR
signal for (3,5-dtb-SQ)2Ge (3,5-dtb-SQ ) 3,5-di-tert-butyl-
benzosemiquinone), which indicated the presence of two SQ
(12) Kolesnikov, S. P.; Maksimov, S. N.; Smolenskii, E. A. Russ. Chem.
Bull. 2001, 50, 740-742.
(13) Zefirov, Yu. V.; Zorkii, P. M. Russ. Chem. ReV. 1995, 64, 446-460.
Inorganic Chemistry, Vol. 43, No. 24, 2004 7811

Fedushkin et al.
Figure 3. Molecular structure of 3. Thermal ellipsoids are of 30% probability. Hydrogen atoms are omitted except those localized at nitrogen atoms.
Figure 4. Orientation of the two dpp-BIAN ligands in the cation
{[(dpp-BIAN)(H)2]2Cl}+ of 3.
radical anions in (3,5-dtb-SQ)2Ge.14 Besides a strong and
sharp signal of the monoradical (single line, g ) 2.008), the
ESR spectrum of (3,5-dtb-SQ)2Ge at 77 K showed the
resonance at half-field, demonstrating the presence of bi-
radical species. For the monoradical signal, no HFC constants
were reported. The parameters of the ESR signal of 1 may
be compared with those of the alkali and alkaline-earth
metal complexes of the dpp-BIAN radical anion (e.g.,
(dpp-BIAN)M (M ) Li, Na)3b and (dpp-BIAN)MgX (X )
Cl, Br, I, OAr)).3e-g The HFC constants to 14N vary in these
3g
compounds from 0.44 mT in (dpp-BIAN)MgI(DME)2
(DME ) 1,2-dimethoxyethane) to 0.46 mT in (dpp-BIAN)-
Figure 5. (a) ESR spectrum of 1 in toluene solution. (b) Calculated
Na3b and 0.83 mT in (dpp-BIAN)Mg(antryl-9-oxy)(THF)2.3e
spectrum (AN ) 0.48 (2 N), AGe ) 0.96, ACl ) 0.78 (35Cl), ACl ) 0.65
(37Cl), AH ) 0.11 (4 H) mT, g ) 2.0014).
(dpp-BIAN)Na is the only example where a coupling to
the metal (ANa ) 0.17 mT) was observed.3b For complexes
[(dpp-BIAN)MgX(L)]n (X ) Cl, Br, L ) THF, n ) 2; X )
I, L ) DME, n ) 0),3g the HFC constant to the halogen
atom was detected only for the iodine derivative (AI ) 0.27
mT), in which the Mg-I bond almost lies perpendicular to
the metallacycle similar to that in 1. The larger coupling to
Cl in 1 (ACl ) 0.78 (35Cl) and 0.65 (37Cl) mT) compared to
3g
that to I in (dpp-BIAN)MgI(DME)2 may be explained by
a high degree of covalence in Ge to ligand bonding. One of
the distinct features of the ESR signal of the dpp-BIAN
radical anion in 1 is the coupling of the unpaired electron to
four protons (AH ) 0.11 mT). In alkali and alkaline-earth
metal complexes of dpp-BIAN such a coupling has not been
observed. We attribute this coupling to the hydrogen atoms
in ortho and para positions of the naphthalene system (rela-
tive to the diimine fragment). Coupling constants are rather
(14) El-Hadad, A. A.; McGravey, B. R.; Merzougui, B.; Sung, G. W.;
Trikha, A. K.; Tuck, D. G. J. Chem. Soc., Dalton Trans. 2001, 1064-
1052.
7812 Inorganic Chemistry, Vol. 43, No. 24, 2004

DiWalent Germanium with a Radical-Anionic Ligand
cane (AN ) 0.343 (4 N), AH ) 0.064 (8 H), AH ) 0.74 (4 H)
mT).19 Similarity of the parameters of the ESR signals for 2
and 3 allowed the suggestion that in solution these com-
pounds exist as solvent-separated ion pairs and the influence
of Cl- and [GeCl3]- anions on the electronic structures of
dpp-BIAN radical cations is small.
IR and UV-Vis Spectroscopic Studies of 1-3. IR and
UV-vis spectra of 1-3 were recorded at room temperature.
The IR spectrum of 1 confirms the radical-anionic character
of the ligand. Whereas ν(CdN) vibrations of the free
ligand20 range from 1600 to 1700 cm-1, the respective
vibrations of 1 are shifted by ca. 100 cm-1 to lower wave-
numbers. One of the most characteristic absorptions in the
IR spectrum of 1 appears at 765 cm-1 and is assigned to
Ge-N stretching. Except for this absorption, the IR spectra
of 2 and 3 in the 1600-400 cm-1 region are very similar to
that of 1. However, in contrast to 1, the IR spectra of 2 and
3 revealed an absorption caused by ν(N-H) stretching in
the region of 3500-3000 cm-1. In 3, this absorption is shifted
to lower wavenumbers by ca. 200 cm-1. This may be
attributed to the lower covalency of the N-H bond in 3
compared to that of 2 because of the interaction of H(1),
H(2), H(3), and H(4) with Cl(4) (Figure 3). In contrast
to 2, the IR spectrum of 3 exhibits a strong absorption at
660 cm-1, which we assign to the deformation mode of the
Cl(4)‚‚‚H(1, 2, 3, and 4) bonds. This deformation may be
caused by variance of the interligand angle in the “complex”
cation [{(dpp-BIAN)(H)2}2Cl]+ (Figure 4).
The UV-vis spectra for 1, 2, and 3 (Figure 7) were
recorded in diethyl ether. Compound 1 exhibits two absorp-
tions (518, 906 nm), which very likely are of the same nature
as in (dpp-BIAN)•-Mg(antryl-9-oxy)(THF)2 (528, 1013
nm).3e However, in contrast to the Mg complex, compound
1 also revealed absorption with maxima of 420 nm. One can
expect that the two long-wave absorptions in 1 arise from
the ligand n-π* and π-π* transitions, whereas the band at
420 nm is presumably caused by the ligand-to-germanium
charge transfer. The electronic spectra of 2 and 3 differ little
from each other. Both 2 and 3 show three absorptions in the
regions 400-450, 550-600, and 700-750 nm (2, 420, 596,
724; 3, 415, 562, 750 nm), whereas the electronic spectrum
of the neutral diamine (dpp-BIAN)H2 shows only a single
absorption at 536 nm.10 Quantum chemical calculations on
the radical cation [(dpp-BIAN)(H)2]+ might help to assign
these absorptions and are currently in progress.
Figure 6. (a) ESR spectrum of 3 in Et2O solution. (b) Calculated spectrum
(AN ) 0.53, AH ) 0.48 mT, g ) 2.0031).
small, thus indicating that the unpaired electron is mainly
delocalized over the diimine part of the ligand. The germa-
nium HFC constant (AGe ) 0.96 mT) in 1 is 10 to 20 times
smaller than those in germanium-centered radicals R3Ge‚ (R
) CH(TMS)2, 9.9 mT; R ) N(TMS)2, 17.1 mT; R )
N(TMS)(tBu), 17.3 mT; R ) N(GeMe3)2, 14.5 mT; R )
4,5,6-Me3-2-tBuC6H, 8.5 mT)15 but close to that calculated
for radical anions of tetraphenyl-1-germacyclopenta-2,4-diene
[Ph4C4GeH2]•- (0.57 mT)16 and experimentally observed for
the radical anion of digermanyne [{1,2-(2,6-Pr2C6H3)-
C6H3}2Ge2]•- (0.75 mT).17
Radical cations of (dpp-BIAN)H2 in 2 and 3 can be
detected by ESR spectroscopy at room temperature. The
experimental spectrum together with its simulation is shown
in Figure 6.
Both compounds reveal ESR signals of seven lines
indicating coupling of the unpaired electron to two 14N and
1
two H nuclei (AN ) 0.53, AH ) 0.48 mT, g ) 2.0031).
Because of the broadening of the signals, it was not possible
to distinguish if small coupling to the protons of the
naphthalene systems exists. A relatively high hyperfine
1
coupling to two H nuclei proves the crystallographic data
(vide supra), which showed hydrogen atoms directly attached
to N(1) and N(2). To the best of our knowledge, this is only
the second ESR detection of the radical-cationic species
derived from protonated R,R-diimines and the first for which
crystal structure determination has been carried out.
Alberti and Hudson reported the formation of the dipro-
t
tonated Bu-DAD radical cation (isomer A, AN ) 0.73 (2
N), AH ) 0.48 (2 H), AH ) 0.75 (2 H) mT, g ) 2.0032;
isomer B, AN ) 0.66 (2 N), AH ) 0.57 (2 H), AH ) 0.69 (2
H) mT, g ) 2.0033) under photolysis of the parent diimine
tBu-DAD in the presence of di-tert-butylperoxide and a trace
of trifluoroacetic acid.18 The HFC constants of 14N in the
ESR signals of 2 and 3 can also be compared with those of
the radical cation of 1,3,6,8-tetraazocyclo-[4.4.1.13,8]-dode-
Experimental Section
General Remarks. All manipulations were carried out under
vacuum using Schlenk ampules. Tetrahydrofuran, benzene, and
diethyl ether were dried by distillation from sodium/benzophenone.
1,2-Bis[(2,6-diisopropylphenyl)imino] acenaphthene (dpp-BIAN)
(15) Della Bona, M. A.; Cassani, M. C.; Keates, J. M.; Lawless, G. A.;
Lappert, M. F.; Stu¨rmann, M.; Weidenbruch, M. J. Chem. Soc., Dalton
Trans. 1998, 1187-1190.
(19) Zwier, J. M.; Brouwer, A. M.; Keszthelyi, T.; Balakrishnan, G.;
Offersgaard, J. F.; Wilbrandt, R.; Barbosa, F.; Buser, U.; Amaudrut,
J.; Gescheidt, G.; Nelsen, S. F.; Little, C. D. J. Am. Chem. Soc. 2002,
124, 159-167.
(20) (a) Paulovicova, A. A.; El-Ayaan, U.; Shibayama, K.; Morita, T.;
Fukuda, Y. Eur. J. Inorg. Chem. 2001, 2641. (b) Paulovicova, A. A.;
El-Ayaan, U.; Umezava, K.; Vithana, C.; Ohashi, Y.; Fukuda, Y. Inorg.
Chim. Acta 2002, 339, 209.
(16) Faustov, V. I.; Egorov, M. P.; Nefedov, O. M.; Molin, Yu. N. Phys.
Chem. Chem. Phys. 2000, 2, 4293-4297.
(17) Pu, L.; Phillips, A. D.; Richards, A. F.; Stender, M.; Simons, R. S.;
Olmstead, M. M.; Power, P. P. J. Am. Chem. Soc. 2003, 125, 11626-
11636.
(18) Alberti, A.; Hudson, A. J. Organomet. Chem. 1983, 241, 313-319.
Inorganic Chemistry, Vol. 43, No. 24, 2004 7813

Fedushkin et al.
Figure 7. UV-vis spectra of 1, 2, and 3 in Et2O at 293 K.
was prepared according to the published procedure.20a GeCl2(1,4-
dioxane) was purchased from ABCR. Gaseous HCl was obtained
from anhydrous H2SO4 and NaCl. Melting points were measured
in sealed capillaries. The IR spectra were recorded on a Specord
M80 spectrometer. The UV-vis spectra were recorded on a Perkin-
Elmer λ 25 spectrometer using a Pyrex glass cell (5 × 15 × 30
mm3). The ESR spectra were obtained using a Bruker ER 200D-
SRC spectrometer equipped with a low-temperature controller ER
4111 VT. Signals of 1-3 were referred to the signal of diphe-
nylpicrylhydrazyl (DPPH, g ) 2.0037).
After the mixture was shaken, within a few seconds the reaction
solution turned deep green. The mixture was centrifuged, and the
solution was decanted and concentrated (15 mL) at 60 °C by
removal of the solvent in a vacuum. In 40 h, dark green, prismatic
crystals of 2 were isolated. Yield 0.39 g (57% calcd on dpp-BIAN
used). Mp > 150 °C (dec). IR (Nujol): 3275-3240 m, 3200-
3150 m, 3050 w, 3025 w, 1610 s, 1585 s, 1515 vs, 1450 vs, 1380
s, 1320 m, 1295 w, 1250 w, 1215 w, 1180 m, 1140 w, 1095 w,
1055 w, 1040 w, 1030 w, 930 m, 885 w, 820 s, 800 s, 765 s, 745
w, 720 w, 610 s, 565 m, 520 m, 500 w, 475 w, 455 m cm-1. Anal.
Calcd for C36H41Cl3GeN2 (680.65): C, 63.52; H, 6.07. Found: C,
63.30; H, 6.09. UV-vis (20 °C, Et2O): λ 420, 596 (555 sh),
724 (796 sh). ESR (20 °C, Et2O): AN ) 0.53 (2 N), AH ) 0.48 (2
H) mT.
Synthesis of (dpp-BIAN)GeCl (1). From dpp-BIAN and
GeCl2(C4H8O2). To a suspension of free dpp-BIAN (0.5 g, 1.0
mmol) in Et2O (40 mL), the dioxane adduct of germanium
dichloride GeCl2(C4H8O2) (0.46 g, 2.0 mmol) was added. The
ampule was shaken at room temperature, and the color of the
solution changed within few minutes from orange to cherry red.
The solution was filtered off and concentrated to 20 mL by
evaporation of the solvent in a vacuum. The small amount of
microcrystalline solid formed during evaporation of the solvent was
redissolved under heating. In 2 days, compound 1 was isolated as
deep-red crystals (0.13 g, 21%). Mp > 200 °C (dec). IR (Nujol):
3055 w, 1535 s, 1450 m, 1315 s, 1250 m, 1210 w, 1185 m, 1145
w, 1080 w, 1050 m, 1030 w, 935 m, 865 m, 820 s, 800 s, 795 w,
765 vs, 600 w, 545 w cm-1. Anal. Calcd for C36H40ClGeN2
(608.74): C, 71.03; H, 6.62. Found: C, 70.75; H, 6.58. UV-vis
(20 °C, Et2O): λ 420, 518 (489 sh), 906. ESR (12 °C, toluene):
AN ) 0.48 (2 N), AGe ) 0.96, ACl ) 0.78 (35Cl), ACl ) 0.65 (37Cl),
AH ) 0.11 (4 H) mT. Concentration of the solution yielded a
mixture of crystalline 1 and colorless crystals (mp 147 °C).
From (dpp-BIAN)Na and GeCl2(C4H8O2). A solution of
(dpp-BIAN)Na was prepared in situ from dpp-BIAN (0.5 g, 1.0
mmol) and sodium (0.023 g, 1.0 mmol) under stirring for 24 h in
40 mL of Et2O. To this solution, the dioxane adduct of germanium
dichloride GeCl2(C4H8O2) (0.23 g, 1.0 mmol) was added. The
reaction mixture turned quickly from red to cherry red. The mixture
was centrifuged, and the solution was separated from the NaCl
precipitate by decantation. Compound 1 was isolated from the
concentrated Et2O solution as deep-red crystals in 75% yield (0.46
g). Analytical data are identical to those obtained for the compound
in the procedure described above.
Reaction of (dpp-BIAN)GeCl (1) with 3 Equiv of HCl:
Synthesis of [{(dpp-BIAN)(H)2}2(Cl)][GeCl3]‚2.5(C6H6) (3). A
solution of 1 (freshly prepared in situ from dpp-BIAN (0.5 g, 1.0
mmol), Na (0.023 g, 1.0 mmol), and GeCl2(C4H8O) (0.23 g, 1.0
mmol)) in benzene (40 mL) was cooled to -30 °C and exposed to
gaseous HCl (67.2 mL, 3.0 mmol). After being shaken, within a
few seconds the reaction solution turned deep green. The mixture
was centrifuged, and the solution was decanted and concentrated
(15 mL) at 60 °C by removal of the solvent in a vacuum. In 2
days, dark green, elongated parallelepipeds of 3 were isolated. Yield
0.61 g (43% calcd on dpp-BIAN used). Mp 184 °C (dec). IR
(Nujol): 3120 s, 3080 w, 3025 w, 1610 s, 1585 s, 1515 vs, 1450
vs, 1380 s, 1320 m, 1290 w, 1240 w, 1205 w, 1185 m, 1135 w,
1095 w, 1050 w, 1040 w, 1030 w, 930 m, 900 w, 815 s, 795 s, 755
s, 740 w, 705 w, 690 w, 660 vs, 590 m, 530 w, 510 m
cm-1. Anal. Calcd for C87H99Cl4GeN4 (1415.09): C, 73.84; H,
7.05. Found: C, 71.49; H, 6.65. UV-vis (20 °C, Et2O): λ 415,
562 (518 sh), 750. ESR (20 °C, Et2O): AN ) 0.53 (2 N), AH
)
0.48 (2 H) mT.
X-ray Crystal Structure Determination of 1-3. The data were
collected on a Bruker SMART APEX diffractometer (graphite-
monochromated Mo KR radiation, ω- and ψ-scan technique, λ )
0.71073 Å) at 100 K for 1 and 3, and at 120 K for 2. The structures
were solved by direct methods using SHELXS-9721 and were
refined on F2 using SHELXL-97.22 All non-hydrogen atoms were
refined anisotropically, and the hydrogen atoms were placed in
calculated positions and assigned to an isotropic displacement
Reaction of (dpp-BIAN)GeCl (1) with 2 Equiv of HCl:
Synthesis of [(dpp-BIAN)(H)2][GeCl3] (2). A solution of 1
(prepared in situ from dpp-BIAN (0.5 g, 1.0 mmol), Na (0.023 g,
1.0 mmol), and GeCl2(C4H8O2) (0.23 g, 1.0 mmol)) in benzene
(40 mL) was cooled to -30 °C and exposed to gaseous HCl (44.8
mL, 2.0 mmol), which was obtained at ambient temperature in an
evacuated Schlenk-like ampule from anhydrous H2SO4 and NaCl.
(21) Sheldrick, G. M. SHELXS-97: Program for the Solution of Crystal
Structures; Universita¨t Go¨ttingen: Go¨ttingen. Germany, 1990.
(22) Sheldrick, G. M. SHELXL-97: Program for the Refinement of Crystal
Structures; Universita¨t Go¨ttingen: Go¨ttingen, Germany, 1997.
7814 Inorganic Chemistry, Vol. 43, No. 24, 2004

DiWalent Germanium with a Radical-Anionic Ligand
parameter of 0.08 Å2. SADABS23 was used to perform area-detector
scaling and absorption corrections.
not result in oxidation of germanium to the +4 oxidation
state but led to a protonation of the ligand and formation of
its stable radical cation.
Conclusion
Acknowledgment. This work was supported by the
Russian Foundation for Basic Research (Grants No. 03-03-
32246 and 1652.2003.3) and the Russian Science Support
Foundation. We thank Dr. O. V. Kuznezova and Mrs. T. I.
Lopatina for recording the IR and UV-vis spectra.
In this paper, we described the synthesis and detailed
characterization, including X-ray crystallography, of the first
germanium(II) compound (1) with a radical-anionic ligand.
The ESR spectroscopic data indicate that the spin density in
1 is distributed over the ligand (N and H nuclei), as well as
over germanium and chlorine atoms. However, values of the
HFC constants allowed the conclusion that the unpaired
electron in 1 is mainly ligand-localized. In contrast to our
initial expectations, reaction of compound 1 with HCl does
Supporting Information Available: IR-spectra for 1-3. Full
details of the X-ray crystallographic data in CIF format of
compounds 1-3, including complete tables of crystal data, atomic
coordinates, bond lengths and angles, and positional and anisotropic
thermal parameters. This material is available free of charge via
the Internet at http://pubs.acs.org.
(23) Sheldrick, G. M. SADABS: Program for Empirical Absorption
Correction of Area Detector Data; Universita¨t Go¨ttingen, Go¨ttingen,
Germany, 1996.
IC048801G
Inorganic Chemistry, Vol. 43, No. 24, 2004 7815