Electronic structure of transition metal-isocorrole complexes: A first quantum chemical study

DFT calculations indicate that the broad electronic-structural features of metalloisocorroles are rather similar to those of analogous metallocorroles. Thus, like their corrole analogues, many metalloisocorroles feature substantially non-innocent ligands. Another key point is that both corroles and isocorroles can exhibit at least two kinds of radical character, a(2) and b(1). However, corrole and isocorrole derivatives also differ significantly in a few ways: for example, the S = 1/2 CoPh complexes of corrole and isocorrole exhibit ground states of different symmetries ((2)A" and (2)A', respectively, in C-s notation), reflecting different interplays of metal(d(pi))-ligand(p(pi)) interactions in corrole versus isocorrole derivatives. The ligand non-innocence phenomena encountered in this study are broadly reminiscent of similar phenomena in peroxidase compound I intermediates and their synthetic models. It seems reasonable, therefore, to adopt the view that this study, along with related studies on corrole derivatives, provides a broader chemical context for appreciating the electronic structures of high-valent heme protein intermediates. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004).