Theoretical study of "deep" fragmentation of hemin ion with successive loss of methyl and vinyl groups

The electronic and geometric structures, energy stability, normal mode frequencies, and spin density distribution have been calculated by the density functional theory B3LYP method with the Gen = 6-31+G*(Fe) + 6-31G(C,H,N,O), 6-31G*, and 6-311++G** basis sets for the deep fragmentation products of the free hemin ion with successive removal of methyl and vinyl groups in the electronic states with different multiplicities. The computation results are compared with the available experimental data and previous computation results for the fragmentation products of the isolated heme molecule and hemin ion with removal of carboxymethyl groups. The trends in the behavior of these properties are analyzed as a function of multiplicity, external charge, and the number of peripheral substituents at the porphyrin core.