Mössbauer and preparative studies of some iron(II) complexes of diphosphines

Abstract

Analytical and Mössbauer spectral data show that Ph₂PCH₂CH₂PPh₂(dppe) forms adducts [FeCl₂(dppe)] and [FeI₂(dppe)], and that [FeCl₂(dppe)₂] does not exist. The phosphine 1,2-C₆H₄(PPh₂)₂(opdp) forms adducts FeX₂(opdp)₂, which exists in one form (high-spin, trans octahedral) for X = Cl, and in two isomeric forms for X = Br or I. One isomer for X = I is high-spin, trans octahedral, and the other is ionic low-spin, and five-co-ordinate. A comparison is made of these structures and of their Mössbauer spectra with those of derivatives of Me₂PCH₂CH₂PMe₂, Et₂PCH₂CH₂PEt₂, Prⁱ₂PCH₂CH₂Prⁱ₂, and Ph₂PCH₂PPh₂.