Reactions of metal carbonyl derivatives. Part IX. The synthesis, infrared spectra, and Mössbauer spectra of some tertiary and ditertiary phosphine, arsine, and stibine derivatives of bis(µ-methylsulphido-, -ethylsulphido-, and -phenylsulphido-tricarbonyliron)

The reactions of [Fe(CO)3SR]2(R = Me or Et) with the ditertiary phosphines L = Ph2P·[CH2]N·PPh2(n= 1 or 2), cis-Ph2P·C2H2·PPh2 and Ph2P·NEt·PPh2 and the ditertiary arsines L = Ph2As·[CH2]n·AsPh2(n= 1 or 2) under various experimental conditions have been studied. A number of different types of products have been isolated. These include [Fe2(CO)5L(SR)2] and [Fe(CO)2LSR]2 in which the ligands are monodentate, [{Fe(CO)2SR}2L] in which the ligand bridges two iron atoms, [Fe(CO)3(SR)2Fe(CO)L] in which the ligand is chelated to a single iron atom and [Fe2(CO)3L2(SR)2] in which one ligand is bidentate and the other monodentate. The nature of the product is shown to depend on the ligand and the reaction conditions. The reactions of [Fe(CO)3SMe]2 with the ligands L′= PEt3, PPh3, P(OMe)3, AsPh3, and SbPh3 have also been studied and the mono-substituted [Fe2-(CO)5L′(SMe)2], bis-substituted [Fe(CO)2L′SMe]2, and tris-substituted [Fe2(CO)3L′3(SMe)2] derivatives have been isolated.Mossbauer and i.r. spectroscopy have been used to elucidate the structures of the above derivatives as well as those of the products of the reactions of [Fe(CO)3SPh]2 with various tertiary and ditertiary phosphines. Systematic variations in the chemical isomer shift and quadrupole splitting are discussed in relation to the bonding in these compounds.