ESR of Hot Ions: Low Spin Pt(III) Complex Ions Produced by γ-Irradiation

Tervalent platinum complex ions have been observed by the electron spin resonance method upon γ-irradiation of both bivalent and quadrivalent complexes. From their g-values, the tervalent complex ions can be classified into two types, one axially symmetric and the other rhombic, the former having typical g-values of 2(g⁄⁄) and 2.4(g⊥), and the latter a g1-value slightly lower than the free electron value of 2.0023. It has been shown by means of ligand field theory that both types have 5d7 low spin electron configuration. The hyperfine interaction due to 195Pt is one order of magnitude larger than that in cobalt complexes with 3d7 low spin configuration, indicating that the configuration interaction involving 6s-orbital is more important than that for 3d transition metal complexes involving 4s-orbital, and that 5d electrons penetrate deeply into inner shells, resulting in core polarizarion.