Electron delocalization of metal electrons in Fe complexes by positronium spin conversion reactions

The rate constants, k_CR, of conversion reactions, CR, of ortho- into para-positronium atoms promoted by 3d paramagnetic complexes of V^II, Cr^II, Cr^III, Mn^II, Co^II and Ni^II ions are linearly correlated with the electron delocalization β caused by the ligands. β's may be evaluated by means of the empirical equation β=1−th, where t and h are constants characteristic of the ion and ligands, respectively. The determination of the unknown t(Fe^II) value is here described. It was derived by means of the rate constants of the CR caused by some Fe^II complexes. It was found that t(Fe^II)=0.14±0.01. A relationship between t and the oxidation number of the metal ions is suggested.