Synthesis and reactivity towards dioxygen of some manganese(II) complexes of tertiary amines. Crystal structures of [{MnI2(NEt3)}2], [{MnI2(NPr3n)}2] and [NHMe3][MnI3(NMe3)]

Abstract

Some manganese(II)–tertiary amine complexes of stoichiometry MnX₂(NR₃) have been prepared for the first time. Magnetic susceptibility and X-ray crystallographic studies on [MnI₂(NR₃)](R = Et or Prⁿ) indicate that the complexes have a dimeric structure, in contrast to the analogous tertiary phosphine complexes which are polymeric. The crystal structure of [NHMe₃][MnI₃(NMe₃)] which contains a mononuclear manganese site has also been determined. This complex is postulated to arise from reaction of a solution of [MnI₂(NMe₃)] with trace quantities of moisture. The reaction of the complexes with dioxygen has also been examined: [MnBr₂(NMe₃)] shows no interaction, [MnI₂(NEt₃)] absorbs 2 mol of dioxygen per mol of complex, whereas [MnI₂(NPrⁿ₃)] absorbs only 1. In contrast to the analogous tertiary phosphine complexes, the [MnI₂(NR₃)] complexes do not exhibit reversible binding of dioxygen.