Carbon-Germanium Hyperconjugation: Solid-State and Gas-Phase Investigations of (Trialkylgermyl)methyl-Substituted Pyridinium Ions
Asimo Karnezis, Richard AJ O'Hair, Jonathan M White
ORGANOMETALLICS | AMER CHEMICAL SOC | Published : 2009
A crystallographic and computational study on 2- and 4-((trialkylgermyl) methyl)pyridinium ions 7a-c and 8a-c provides evidence for strong hyperconjugation between the Ge-CH2 bond and the π-deficient aromatic ring. Isodesmic equations show that the trimethylgermyl substituent stabilizes the pyridinium cations by 20-26 kJ mol-1 relative to the germanium-free analogues. Natural bond orbital analysis reveals that the major contributor to this stabilization is hyperconjugation between the Ge-CH 2 bond and the aromatic π-system and that the strength of this interaction is greater for the 2-substituted ions 8a compared to the 4-substituted ions 7a. Crystallographic analysis of the 2- and 4-tert-bu..View full abstract
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Awarded by Australian Research Council
We thank the Australian Research Council for financial support for financial support (DP0770565) and an award of an APA to A.K. We also thank the Victorian Partnership for Advanced Computing and the Victorian Institute for Chemical Sciences High Performance Computing Facility for the computational time and Professor Carl Schiesser for all his helpful advice with regard to the computational aspect of this paper.