2-Diphenylphosphino-2′-hydroxybiphenyl-based P-ligands and their platinum(II) complexes

2-Diphenylphosphino-2′-hydroxybiphenyl (2), become readily available via a ring opening reaction of a dibenzo[c.e][1,2]oxaphosphorine, was utilized as P-ligand in complexation with dichlorodibenzonitrile platinum to give a Cl2Pt22 complex (4) with trans geometry. The O-benzyl derivative (5) could not be involved in complexation. A bidentate P-ligand (7) obtained by the interaction of hydroxy-diphenylphosphinobiphenyl 2 with chloro-dibenzo[c.e][1,2]oxaphosphorine (1) formed an 8-ring transition metal complex (Cl2Pt7 = 9) in reaction with PtCl2(PhCN)2. Under the conditions of chromatography, separation of the diastereomers of 7 was not possible due to a partial isomerisation by rotation around the biphenyl axis of the molecule that is justified by the average barrier height of 6.0 kcal/mol.The stereostructure of P-ligands 2 and 7, as well as platinum complexes 4 and 9 was evaluated by B3LYP quantum chemical calculations.

Graphical abstractPlatinum complexes (A and B) incorporating 2-diphenylphosphino-2′-hydroxybiphenyl or its O-dibenzo[c.e][1,2]oxaphosphorine derivative, are described whose stereostructure was evaluated by stereospecific NMR couplings and quantum chemical calculations. Atrop isomerism of the bidental P-ligand was observed under chromatography that was justified by calculations.Figure optionsDownload full-size imageDownload as PowerPoint slide