A natural bond orbital analysis of carbanions

The methodology of natural bond orbital (NBO) analysis has been applied to the analysis of alkyl and cycloalkyl carbanions with the objective of finding relationships between donor/acceptor computed stabilization energies and geometry. Bi-linear correlations were derived from computed second order perturbation energies, i.e. strength of negative hyperconjugation, and dihedral angles associated with ethyl and propyl anions. Correlations between anionic hybridization indices and carbanion planarity and hyperconjugation energies were found.