Herbert Kollmar

MO calculations on electrophilic reactions—II : The addition of hydrogen to methylene, a carbene insertion Process

Abstract The addition of hydrogen to methylene, the prototype of methylene insertion reactions, is studied with a modified CNDO procedure. Carbene insertions proceed via non least motion processes. The two product orbitals are formed consecutively, each by a steady combination of an occupied and an empty orbital of the reactants. This principle determines the calculated reaction coordinate and leads to a concerted two step mechanism. The chemical consequences of the mechanism are discussed.

Semi-empirical MO calculations of hydrocarbon radicals with the half electron method

Abstract A derivation for the “half electron method” is given. The half electron method is equivalent to a closed shell calculation of a radical dimer linked by an infinitely long bond with inclusion of the configuration interaction with the doubly excited degenerate state. The dissociation process of ethane into methyl radicals is discussed in some detail. Heats of atomization and equilibrium geometries, obtained with modified CNDO calculations within the half electron scheme, are presented for some hydrocarbon radicals.