Studies on Bis(3,5-Di 1-Oximato)manganese(II) and Its Mixed-Ligand Complexes

Abstract

The synthesis, spectroscopy, and redox-reactivity towards PPh<inf>3</inf> of bis(3,5-di-t-butyl-1,2-benzoquinone 1-oximato)manganese(II), Mn(ox)<inf>2</inf>, and its mixed-ligand complexes, Mn(ox)Lx [Lx = 8-hydroxyquinolinato (L1), 2,2′-bipyridine (bpy) (L2), 1,10-Phenanthroline (phen) (L3) and N-(2-hydroxyphenyl)-3,5-di-t-butylsalicylaldiminato (L4)] complexes, are presented. While some complexes exhibit solid-state ESR spectra they were ESR-silent in toluene or CHCl<inf>3</inf> at 300 K. The reduction of all ESR-silent complexes with an excess of PPh<inf>3</inf>, independently from the nature of secondary Lx ligands, results in the appearance of a six-line hyperfine coupling of 55Mn (I = 5/2) (AMn = 95-100 G) and a seven-line radical signal, which was assigned to phosphiniminophenoxyl type radicals (g = 2.0056-2.0075, AP = 8.5 G and AN = 1.875 G). © 2002 Elsevier Science B.V. All rights reserved.