Crude Picture of (Part of the) Electron Configuration of the Hydroxo-Ferric Heme Species

These articles [Shaik et al., 2005: (http://pubs.acs.org/doi/abs/10.1021/cr030722j); Silaghi-Dumitrescu, 2008: (http://macroheterocycles.isuct.ru/en/system/files/08MHC_79-81.pdf); Filatov et al., 1999: (http://zernike.eldoc.ub.rug.nl/FILES/root/1999/AngewChemFilatov/1999AngewChemIntEdFilatov.pdf)] are some "fun" articles I've been looking over. I wanted to clarify the electron configuration of the singly-bonded hydroxo-ferric heme species, and the oxygen apparently has, effectively, 7 valence electrons (as opposed to 6 in ferryl and perferryl hemes). In that species [Fe(III)-OH], apparently, three electrons are shared between iron and oxygen. From a bookkeeping standpoint, oxygen has a lone pair and an unpaired electron, but they're all pi electrons and aren't in the sigma*(xy) and sigma*(z^2) antibonding molecular orbitals for the Fe-O species. Two of these three electrons shared by iron and oxygen, in the Fe(III)-OH species, are in a dxz molecular orbital [one of the d(pi)-p(pi) interactions] (Shaik et al., 2005, Fig. 4). The other shared electron is in a pi*(xz) pi-antibonding molecular orbital. The electron configuration of ferryl heme is easier to understand than that, but it's necessary for me to understand what some of these authors are trying to refer to, with regard to the hardcore chemistry, when they "do" try to describe the electron configurations of these species.