Electronic Structure of Iron Phthalocyanine and Its Analogs: A Theoretical Study

摘要

Molecular electronic structures of the dianions and iron complexes of phthalocyanine and other macrocyclic compounds (i.e., tetrabenzoporphyrin, tetrazaporphyrin and porphyrin) which are of interest in oxygen electrocatalysis have been calculated using CNDO/INDO molecular orbital methods. Significatn differences are found between the electron distributions in phthalocyanine and porphyrin due mainly to a difference in the nature of the atom bridging the indole and pyrrole ligands. Both iron complexes of phthalocyanine and porphyrin have a quintuplet molecular electronic ground state with iron in an intermediate spin state in the former and high spin in the latter. Binding of oxygen to the iron center in model compounds of iron phthalocyanine and iron porphyrin was studied. Side-on configuration appears to be preferred in the oxygen-phthalocyanine system and end-on bonding in the oxygen-porphyrin complex. The effect of catalyst support, electron delocalization by dimerization, and protons in solution on the oxygen binding by iron phthalocyanine was also examined and preliminary results are described. 2 figures, 3 tables. (ERA citation 08:021249)