Metal complexes of chiral phosphorylalkoxides: Crystal structure of dichlorobis[(1S)-2-(diphenylphosphoryl)-1-methylethanolato]titanium(IV)

The chiral alcohols, (1S)-2-(diphenylphosphoryl)-1-methylethanol (S-Hdpomeo) and (1R)-2-(diphenylphosphoryl)-1-phenylethanol (R-Hdpopeo), have been synthesised in optically pure form by a simple two-step procedure. They can be readily deprotonated and the monoanions L so formed co-ordinate readily to Ti-IV or Mo-VI to give complexes of the type [TiCl(2)L(2)], cis-[MoO2(acac)L] or cis-[MoO(2)L(2)]. The complex [TiCl2(S-dpomeo)(2)] crystallised in the orthorhombic space group P2(1)2(1)2(1), with a = 11.572(1), b = 13.209(1), and c = 20.452(1) Angstrom. It is octahedral, with trans chlorides, and cis phosphoryl and alkoxide donors. The six-membered chelate rings adopt asymmetric boat conformations, with equatorially projecting methyl groups. This is the first structurally characterised complex containing a phosphorylalkoxide ligand. The NMR spectroscopic evidence suggests retention of the solid-state structure upon dissolution, and considerable rigidity in the chelate rings.