Wide bite angle amine, arsine and phosphine ligands in rhodium- and platinum/tin-catalysed hydroformylation

New wide bite angle amine, arsine and mixed phosphineamine and phosphinears ine ligands based on xanthene backbones were synthesized. The co-ordination chemistry and the catalytic performance of these ligands were compared to those of the parent phosphine ligands. The amine based xanthene ligands do not form rhodium-hydride complexes and therefore give very poor rhodium hyd roformylation catalysts. The catalytic performance of the xantarsine and th e mixed xantphosarsine ligands is comparable with that of the xantphos liga nds and they form similar (ligand)Rh(CO)(2)H and [(ligand)Rh(CO)(2)](2) com plexes. In the platinum/tin-catalysed hydroformylation the xantarsine and t he mixed xantphosarsine ligands proved to be superior to the xantphos ligan ds. The remarkably high selectivity and activity that is displayed by the m ixed xantphosarsine ligand is explained by its wide natural bite angle and the formation of cis co-ordinated platinum complexes.