Xantphos as cis- and trans-chelating ligand in square-planar platinum(II) complexes. Hydroformylation of styrene with platinum–xantphos–tin(II)chloride system

Platinum(II) complexes of a diphosphine ligand xantphos (4,5-bis(diphenylphosphino)-9,9-dimethyl-xanthene) have been synthesised and characterised by NMR, conductivity and catalytic investigations. In addition to the parent complex cis-PtCl2(xantphos), trans-platinum(II) complexes of square-planar geometry containing xantphos as a trans-chelating ligand can be obtained due to the large bite angle of the ligand. The platinum–xantphos–tin(II)chloride system acts as active hydroformylation catalyst in the hydroformylation of styrene resulting in high chemo- and regio-selectivities of up to 99.8% and 88%, respectively.