Transition structures for one step nonconcerted oxygen insertion mechanismof oxidation of alkanes with trifluoroperoxyacetic acid

High level calculations (UB3LYP/fi-31G*) on the oxygen insertion by trifluo roperoxyacetic acid (TFPA) into methane and isobutane C-H bonds strongly su pports the viability of a one step nonconcerted mechanism. That is, the O-H bond forms first and the C-O bond formation commences afterwards, but only one first order saddle point, exhibiting high diradical character and stro ng polarization, is present on the energy profile of the minimum energy pat h. No minima corresponding to intermediates were located. IRC analysis sugg ests that the transition structure can collapse directly to products with r etention of configuration at the alkane carbon center. (C) 2001 Elsevier Sc ience Ltd. All rights reserved.