New unsymmetrical thioether- and thiolate-substituted ferrocenediyl ligands and their metal complexes

A series of new unsymmetrical 1,1ʹ-disubstituted ferrocenediyl ligands featuring thioether or thiolate substituents have been conveniently synthesised. The chelating nature of the ligands is shown by coordination with a range of transition metal centres and bridged metal dimeric species are observed with platinum and palladium. Electrochemical studies show that the diferrocene species is a partially delocalised Robin-Day Class II system, whilst on coordination of metal centres to the monoferrocene ligands, the oxidation potential of the ferrocene subunit is greatly increased ranging from 0.25 to 0.60 V upon passing from platinum(II) to palladium(II) ions. Interestingly, the outer ferrocenediyl subunits of the dimeric complexes indicate electronic interaction through the diplatinum or dipalladium backbones. The chromium- and vanadium-containing species act as low activity, pre-catalysts for ethylene polymerisation.