Magnetic susceptibility and electron paramagnetic resonance studies on bis(2,2′-bipyridyl)thioureacopper(II) perchlorate

Abstract

Single-crystal, polycrystalline, and frozen solution e.p.r. spectra of bis(2,2′-bipyridyl)thioureacopper(II) perchlorate are reported. The low temperature (1·6–67·7 K) magnetic susceptibility of a polycrystalline sample of the complex is also reported. The intermolecular exchange interaction was found to be extremely small (ca. –0·02 cm^–1) which allowed the observation of magnetically non-equivalent sites. The molecular parameters determined (g_z= 2·020 ± 0·005, g_x= 2·168 ± 0·005, and g_y=2·141 ± 0·005 and K ≃ 0·64) indicate a predominantly d_3z²–r² ground state but with significant mixing of excited states and with substantial delocalization of the unpaired spin density.