Spectroscopic Studies on bis(3,5-di-t-butyl-1,2-benzoquinone 1-oximato)copper(II) and Its Mixed-Ligand Complexes. Copper(II)-Radical Ferromagnetic Coupling

Abstract

Bis(3,5-di-t-butyl-1,2-benzoquinone 1-oximato)copper(II), Cu(ox)2, and its mixed-ligand complexes, Cu(ox)L-x [L-x = 8-hydroxyquinolinato (L-1), N-Phenyl-salicylaldimine (L-2) N-phenyl-3,5-di-t-butylsalicyl-aldiminato (L) and N-(2-hydroxyphenyl)-3 5-di-t-butylsalicyl-aldiminato (L-4)], were prepared and their spectral behavior as well as redox-reactivity towards PPh3, (m-ClC6H4)(3)P, (m-CH3C6H4)(3)P and PPh2-(CH2)(4)-PPh2 studied by analytical and spectroscopic (IR, UV-vis, ESR) techniques and magnetic measurements. Cu(ox)2 and Cu(ox)L-4 complexes prepared in air show mu(ef) values of 2.84 and 3.33 mu(B), respectively, and are consistent with an S = 1 and S = 3/2 ground states. Both compounds are formulated as copper(II)-radical complex exhibiting intramolecular ferromagnetic coupling between the orthogonal d(x2-y2) magnetic orbital of the Cu-II ion and that of the pi-radical ligand.