The coordination chemistry of manganese. Part VI. [1–4]. Bis(tetrahydrofuran)manganese(II) halide complexes; synthesis and characterisation

Abstract

The solid state structures of Mn(THF) 2X 2 (THF = tetrahydrofuran; X = Cl, Br, I) appear to be halide-bridgedpseudooctahedral polymers which do not exhibit EPR signals. The EPR-active Mn(THF) 2(NCS) 2 is a pseudotetrahedral monomer. In tetrahydrofuran solution the Mn(THF) 2X 2 complexes react with PPhMe 2 to form a complex which can reversibly absorb/desorb molecular oxygen in a manner analogous to the authentic haem analogues Mn(PPhMe 2)X 2. However, reaction of Mn(THF) 2X 2 with PPhMe 2 in acetonitrile, followed by exposure to dioxygen, results in rapid decomposition to an EPR-inactive species, presumably manganese(III), accompanied by production of some OPPhMe 2. An authentic sample of Mn(PPhMe 2)Br 2 in acetonitrile also undergoes similar decomposition on exposure to dioxygen. Polarographic and other characterisation data are reported for the Mn(THF) 2X 2 complexes.