Full geometry optimizations have been carried out in order to determine the structure of the global minimum for the quintet state of the isolated alpha-center [FeO](2+) using the neutral cluster OFe(OH)(2) as a model. The intrinsic reaction coordinate and a potential energy cut were calculated aiming at the examination of other low-energy structures. The absolute minimum here reported for the title species differs from the structures reported in other molecular orbital-based studies. Such a structure has been analyzed in order to determine the oxidation state of the Fe atom in the ferryl catalyst. (C) 2014 Elsevier B.V. All rights reserved.