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)

Abstract

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.

Mössbauer 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.