Quantum-chemical calculations of neutral and charged ironporphyrin (FeP, FeP+1 and FeP-) systems were performed using B3LYP and MP2 methods. It was shown that all ground states of FeP (S = 1), FeP+1 (S = 3/2) and FeP- (S = 1/2) systems have C-2v symmetry. During the first step of electron transfer process an electron goes to beta-LUMO - 1 Fe d(yz)-orbital of FeP+1. The second electron goes to beta-LUMO of Fel? which is attributed to pi-system of porphyrin ring. The 3s- and 3p-orbitals do not play a significant role in the electron transfer process. The ability of FeP-1 system to form pi-dative chemical bond is low. The formation of pi-pi-complexes is preferable. (c) 2005 Elsevier B.V. All rights reserved.