In Situ Formation of PBiP Ligands upon Complexation of a Mixed Phosphane/Bismuthane with Group 11 Metal Ions

The behavior of a xanthene derivative with one bismuthane and one phosphane function, Xan­(PPh2)­(BiPh2), as a ligand toward group 11 metal cations was investigated. It was found that contact with [Cu­(MeCN)4]­OTf, AgOTf, [Au­(PPh3)­OTf], in all three cases leads to a transformation of Xan­(PPh2)­(BiPh2) into a tridentate PBiP system, where a BiPh unit connects two phosphinoxanthyl moieties. In the resulting compounds, [PhBi­(Xan­(PPh2))2Cu]­OTf, 1, [PhBi­(Xan­(PPh2))2Ag]­OTf, 2, and [PhBi­(Xan­(PPh2))2AuPPh3]­OTf, 3, the metal cations are coordinated tetrahedrally by two phosphane donors, one bismuthane donor and a fourth ligand, corresponding to OTf– in case of 1 and 2, or PPh3 in the case of 3. DFT calculations in combination with NBO analysis showed that the bismuth atoms in these PBiP ligands act as σ-donors. 3 thus corresponds to the first known AuI ← BiIII complex.