Complexes of tertiary phosphines and tertiary arsines with molybdenum(IV)

Abstract

The complex [MoCl₄(EtCN)₂] reacts in dichloromethane with alkaryl and triaryl tertiary phosphines to form the paramagnetic, maroon complexes trans-[MoCl₄L₂](L = tertiary phosphine). In ethanol, however, tertiary phosphines react with the ethyl cyanide complex to yield the diamagnetic oxo-complexes, mer-[MoOCl₂L₃], which are also obtained directly from molybdenum pentachloride and the phosphine in ethanol. These, by metathesis, give the complexes mer-[MoOX₂L₃](X = I, Br, NCS, or NCO). The oxo-complexes are generally green or blue according to whether the oxygen is trans to L or X respectively. ¹H n.m.r. and i.r. spectra were determined for structural diagnosis.