ATROPISOMERIC DIARYL-CORE PHOSPHOLE LIGANDS - PD-II AND PT-II COMPLEXES WITH P-PHENYL DINAPHTHOPHOSPHOLE

The behaviour of P-phenyl dinaphthophosphole (L), the first phosphole with axial chirality, towards some ds metal centres has been investiga ted. L acts as a monodentate phosphorus ligand and readily substitutes neutral or anionic ligands coordinated to Pd(II) and Pt(II) centres. New complexes L MCl2 with exclusive (M = Pt) or predominant (M = Pd) c is geometry have been obtained by reaction with K2[PtCl4] and (PhC2)2P dCl2. Reaction of L with ortho-metallated chloride bridged dinuclear [ (C-N)MCI]2 complexes (HC-N - 2-benzylpyridine, M = Pt; HC-N = N,N-dime thyl-(R)-alpha-methylbenzylainine, M = Pd) promotes bridge splitting l eading to the mononuclear species L(C-N)MCI with a trans P-M-N arrange ment. The X-ray structure of the Pd complex shows that the coordinatio n around the metal is essentially square planar with normal bond dista nces. The dihedral angle between the average planes of the naphthyl gr oups of the phosphole (33-degrees) and Tolman's cone angle theta of th e ligand (136) have been determined. In some complexes, the phosphole ligand is fluxional at room temperature and undergoes rapid atropisome rization of the binaphthyl framework even in the bound state.