SYNTHESIS AND CRYSTAL-STRUCTURE OF A LANTHANUM COMPLEX WITH A DIPHENYLPHOSPHIDE LIGAND

Reaction of a solution of [LaL3(Ph3PO)] [L = N(SiMe3)2] with Ph2PH followed by Ph3PO yields [LaL2(PPh2)(Ph3PO)2], which has been isolated as highly air-sensitive orange crystals and characterised by solution NMR spectroscopy (P-31 and H-1) and X-ray crystallography. The structure was refined to a final R value of 0.056 and shows the complex to have a terminal PPh2- ligand with planar co-ordination at P. Variable-temperature P-31 NMR spectroscopy indicates rapid exchange between free and co-ordinated Ph3PO at room temperature but at 193 K is consistent with the solid-state structure with two Ph3PO ligands.