Construction of valence bond structures for {FeNO} 7 nitrosyl heme and non-heme complexes.

For {FeNO}7 nitrosyl heme and non-heme complexes, with 17 valence shell electrons, FeII NO, FeII NO* and FeIII NO- valence bond structures of the increased-valence type are generated primarily from Lewis valence bond structures by delocalizing non-bonding electrons into diatomic bonding molecular orbitals. Valence bond formulations for the reactions 2MbNO + 2H+ → 2metMb + N2 O + H2 O and cis MbNO + NO- + 2H+ → metMb + N2 O + H2 O are also presented.