Stabilization of nonclassical types of valence bond orientation at the carbon atom in organoboron compounds

The complete topological structure of the potential energy surface (PES) of methane in the inversion region was studied by theab initio CCD(full)/6-311++G^** method. The necessity of taking into account nuclear motions was shown. Penta- and hexacoordination of carbon atoms in boron-containing organic compounds was investigated by theab initio MP2(full)/6-31G^** and MP2(full)/6-311++G^** methods. The CB₄H₄Li₂, CB₆N₂H₂, and CB₆O₂ systems containing hexacoordinated carbon atoms correspond to rather deep minima on the relevant PES and can be the subject of synthetic studies. According to theab initio calculations, pyramidal boron-containing systems with hypercoordinated carbon atoms, which fulfill the “8e rule,” also correspond to rather deep PES minima and can be detected experimentally. Dedicated to Academician V. I. Minkin on the occasion of his 65th birthday. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 786–796, May, 2000