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¨
A. Pal and R. Herbst-Irmer, Organometallics, 2008, 27, 5459.
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Commun., 2007, 85.
11 For carbene–metallene analogues, see: (a) W. M. Boesveld,
B. Gehrhus, P. B. Hitchcock, M. F. Lappert and P. von R.
Schleyer, Chem. Commun., 1999, 755; (b) B. Gehrhus,
P. B. Hitchcock and M. F. Lappert, J. Chem. Soc., Dalton Trans.,
Fig. 4 Frontier orbitals of model compound 7 (KS-HOMO ꢀ4.024 eV,
KS-LUMO ꢀ1.138 eV).
suggests some ionic character of the Ge–M bonds. The
pronounced electron acceptor character of the C3N2Ge ring
is also reflected by the calculated NICS (nucleus independent
chemical shift) values for 6 and 7, which revealed strongly
negative values [6: NICS(0) = ꢀ8.8, NICS(1) = ꢀ8.2, 7:
NICS(0) = ꢀ7.6, NICS(1) = ꢀ7.4]. This confirms the
presence of a 6p-aromatic stabilization in 4 and 5 as concluded
2000, 3094; (c) F. E. Hahn, L. Wittenbecher, M. Kuhn, T. Lugger
¨
and R. Frohlich, J. Organomet. Chem., 2001, 617/618, 629;
¨
¨
(d) A. V. Zabula and F. E. Hahn, Eur. J. Inorg. Chem., 2008,
1039.
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¨
Soc., 2008, 130, 9640.
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P. P. Power, Organometallics, 2001, 20, 1190.
14 Crystal data for 4: C45H65Ge2N3, M = 805.19, monoclinic, space
group C2/c, a = 44.536(2), b = 9.8204(5), c = 21.8135(10) A,
1
from H NMR data (see above).
In summary, the new M(I)–M(I) compounds 4 and 5 repre-
sent the first unsymmetric substituted dimetallylenes having
M(I)–M(I) s bonds with some ionic character. This might
imply unusual redox chemistry with the possibility for partial
reduction and oxidation of the low-valent M sites (Ge, Sn),
such as germylene and stannylene radical cation or anion
species.19 Additionally, the compounds are currently being
investigated for their suitability to serve as electron-rich donor
ligands for transition metals with varying coordination modes.
We gratefully acknowledge financial support from the Deutsche
Forschungsgemeinschaft, the Alexander von Humboldt
Foundation and the JSPS (fellowship for S. I.).
b = 116.030(4)1. V = 8572.7(7) A3, T = 150 K, Z = 8, rcalc
=
1.248 Mg mꢀ3, m(Mo Ka) = 1.436 mmꢀ1, 7493 reflections
measured, 3798 unique (Rint = 0.095) which were used in all
calculations. R(Fo) = 0.0559 (I 4 2s(l)), wR(Fo2) = 0.0966 (all
data), GOF = 0.917. Crystal data for 5: C46H65GeN3Sn, M =
ꢀ
851.29, triclinic, space group P1, a = 8.67780(10), b = 12.0514(4),
c = 21.0797(6) A, a = 96.333(2)1, b = 97.393(2)1, g = 99.141(2)1.
V = 2139.08(10) A3, T = 150 K, Z = 2, rcalc = 1.322 Mg mꢀ3
,
7496 reflections measured, 6141 unique (Rint = 0.025) which were
used in all calculations. R(Fo) = 0.0310 (I 4 2s(l)), wR(Fo2) =
0.0733 (all data), GOF = 1.001.
15 (a) J. T. Snow, S. Murakami, S. Masamune and D. J. Williams,
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M. Weidenbruch, Organometallics, 1999, 18, 3159.
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22, 215.
Notes and references
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18 DFT calculations of the model compound of LGe–GeL0 [L =
CH{CMe(NPh)}2, L0 = CH(CMe)2NPh] (6) was performed at the
B3LYP/6-31(d) level and model compound LSn–GeL0 [L =
CH{CMe(NPh)2, L0 = CH(CMe)2NPh] (7) was performed at
B3LYP level using 6–31G(d) basis set for Ge, N, C and H atoms
and the LANL2DZ level for the Sn atom.
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ꢁc
This journal is The Royal Society of Chemistry 2009
Chem. Commun., 2009, 2661–2663 | 2663