Preparation of the solvated iron(II) cation in acetonitrile using high oxidation-state fluorides and its reaction with trimethyl phosphite

Abstract

The cation [Fe(NCMe)₆]²⁺ is formed from reactions in acetonitrile of iron metal with WF₆, MoF₆, PF₅, or the NO⁺ cation and from the reaction of iron(II) fluoride with PF₅. Oxidation to Fe^III is not observed using binary fluorides or NO⁺, but [Fe(NCMe)₆]²⁺ is oxidised by chlorine in MeCN to give the tetrachloroferrate(III) anion. The MeCN co-ordinated to Fe^II is replaced by trimethyl phosphite giving [Fe(NCMe){P(OMe)₃}5]²⁺ as the final product at room temperature. Some of the intermediate complexes in this reaction have been identified in solution by ³¹P{¹H} n.m.r. spectroscopy.