Influence of stereochemistry on the formation and reactivity of phosphorus-bridged dinuclear metal carbonyls. Part IV. Reaction of di-µ-dimethylphosphido-bis(tricarbonyliron) with halogens and the crystal structure of di-µ-dimethylphosphido-bis(iodotricarbonyliron)

Abstract

The addition of one mole of halogen to (OC)₃Fe(PMe₂)₂Fe(CO)₃ results in cleavage of the metal–metal bond to give dihalide derivatives.

The structure of the di-iodide, (OC)₃FeI(PMe₂)₂IFe(CO)₃, has been determined by X-ray diffraction. The complex has a centrosymmetrical dioctahedral structure, with the iodine atoms trans to one another and lying above and below the planar di-µ-phosphido-bridge which joins the iron atoms. The iron–iron distance is 3·59 Å and the phosphorus–phosphorus distance 2·88 Å. The iodine atoms introduce some distortion into the molecule, and there is evidence that the phosphorus atoms exert an influence on the trans carbonyl groups, whilst the iodine atoms have little or no trans influence.