Cyclization and rearrangement in the reaction of allylbis(dimethylglyoximato)cobalt(III) complexes with tetracyanoethylene. Crystal structure of trans-3,3,4,4-tetracyano-2-phenylcyclopentylbis(dimethylglyoximato)imidazolecobalt(III)

Abstract

The nucleophilic terminus is that with greater negative charge and highest HOMO coefficient; the electrophilic terminus has largest LUMO coefficient and the least negative (or most positive) ~h a r g e . '~,~,~ (4) MINDO/2 and MIND0/3 optimized geometries: P. Caramella, R. W. Gandour, J. A. Hall, C. G. Devilie, and K. N. Houk, J. Am. Chem. Soc., in press. These calculations also predict the trends obtained here by ab initio techniques: in MIND0/3 (MINDO12) the HCN angles are 116' (1 14'), 126' (122'), and 159' (150') for the ylide, imine, and oxide, respectively. The linear nitrile oxide is only 0.1 (0.2) kcal/mol higher in energy than the bent. (5) A. Padwa. M. Dharan, J. Smolanoff, and S. I. Wetmore, Jr., J. Am. Chem.