MOSSBAUER-SPECTRA OF SOME LOW-SPIN IRON(II) COMPLEXES WITH DITERTIARY PHOSPHINES

The Mossbauer spectral data for a range of low-spin iron(II) complexes [FeX(Y) (diphosphine)2]n+ (n = 0 or 1), where X and/or Y = Cl, Br, MeNC, MeCN, H, N2, H-2, CO, etc., are reported. The isomer shifts and quadrupole splittings have been analysed in terms of ligand partial values assuming that additivity holds, and the partial values are discussed in terms of the bonding properties of the ligands. It is concluded that the partial isomer shifts are of limited use because of the small range of values. Partial quadrupole splittings (p.q.s.) are more informative, and are best computed with reference to p.q.s. (H) = 0.00.