The energy and geometries of the lowest 2A1 and 2E states of the product resulting from lithium atom insertion into a C-H bond of methane in C3v symmetry were obtained by ab initio molecular orbital calculations. Geometries were optimized with three different basis sets, STO-3G, 3-21G, and 6-31G**. The possible pathways to insertion of the lithium atom into a CH bond of methane were also considered. The geometry of the more stable 2A1 state suggested that the inserted molecule is best described as a methyl radical interacting with lithium hydride, where the C-Li bond can be taken as a single electron bond. The 2E state showed a different behavior in that a stronger interaction exists between the methyl and lithium hydride, with the C-Li bond considerably shorter and correspondingly longer C-H bonds. In this case the C-Li bond can be considered as a two-electron bond. The barrier for the formation of methyllithium hydride appears to be associated with the abstraction of the hydride. A brief comparison of the bonding in CH3CuH with that in CH3LiH showed considerable similarities.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry