Reactions of methyl complexes of iron(II) with Lewis bases

Abstract

The ionic complex [Fe(CO)₃(PMe₃)₂Me][BPh₄] reacts with Lewis bases (L) to give [Fe(CO)₂(PMe₃)₂L(COMe)][BPh₄]. Two reaction paths are observed : one involving carbon monoxide insertion followed by attack of the L ligand, and a second in which ligand exchange is followed by an insertion reaction. The relative importance of the two paths depends on the nature and the concentration of L. The neutral complexes [Fe(CO)₂(PMe₃)₂(Me)X] also react with Lewis bases to give [Fe(CO)(PMe₃)₂L(COMe)X]. When X = I the acetyl complex is readily transformed into the corresponding ionic methyl complex [Fe(CO)₂(PMe₃)₂L(Me)]I. The neutral complexes react faster than the ionic ones. The structure of the ionic and neutral complexes has been assigned on the basis of i.r. and n.m.r. evidence.