Different coordination modes of a 1,1′,2,2′-ferrocenyltetraphosphine: bi- and tri-dentate behaviour with group 6 and 7 transition metals

Abstract

The behaviour of 1,1′,2,2′-tetrakis(diphenylphosphino)-4,4′-di(tert-butyl)ferrocene (1), acting as a homoannular or heteroannular ligand, has been studied. Due to the cisoid disposition of the phosphino groups of each ring, different coordination modes are observed. With group 6 metal carbonyls, M(CO)₆, the tetraphosphine acts exclusively as a tridentate ligand. In contrast, the reaction with MnCp(CO)₃ leads to complexes showing 1,1′ and 1,2 bidentate coordination modes. All these complexes have been characterised by ¹H and ³¹P NMR spectroscopy. The molecular structures of the molybdenum complex [(1)Mo(CO)₃] (2b) and the 1,1′ manganese complex [(1)MnCp(CO)] (3) have been established by X-ray diffraction.