Abstract The cationic iron(II) complexes, [Fe(P(OR) 3 ) 5 X] + , have been prepared by reactions involvin oxidation of Fe(P(OR) 3 ) 5 (for X = H, Me, CF 3 ) or addition of phosphites to iron bis(tetrahydrofuran) dihalide complexes (for X = Cl, Br, I). This latter reaction proceeds, under different conditions, through two distinctly different isolable species, both of which have been characterized by