Anomalous E.S.R. Spectra of Nickel Phthalocyanine: A Single-Crystal Study

Abstract

The e.s.r . spectra of single crystals of nickel(II) phthalocyanine show that there are two different magnetic centres, each with axial symmetry (centre 1, g_ll 2.0083, g_l 2.0018; centre 2, g_II 1.986, g₁ 2.006). In both cases, g_llis along the molecular symmetry axis and g_l is in the molecular plane. It is proposed that centre 1 arises from a π-radical cation of the type [Ni^IIPc]^x+O₂^x- analogous to that observed in NiPcI (Schramm et al^-1). Centre 2 may arise from a Ni^III species.