Organometallic chemistry of chiral diphosphazane ligands: Synthesis and structural characterisation

The diphosphazane ligands of the type, (C20H12O2)PN(R)P(E)Y2 (R = CHMe2 or (S)-*CHMePh; E = lone pair or S; Y2 = O2C20H12 or Y = OC6H5 or OC6H4Me-4 or OC6H4OMe-4 or OC6H4But-4 or C6H5) bearing axially chiral 1,1´- binaphthyl-2,2¢-dioxy moiety have been synthesised. The structure and absolute configuration of a diastereomeric palladium complex, [PdCl2(eta2-((O2C20H12)PN((S)- *CHMePh)PPh2}] has been determined by X-ray crystallography. The reactions of [CpRu(PPh3)2Cl] with various symmetrical and unsymmetrical diphosphazanes of the type, X2PN(R)PYY¢ (R = CHMe2 or (S)-*CHMePh; X = C6H5 or X2 = O2C20H12; Y = Y´= C6H5 or Y = C6H5, Y¢ = OC6H4Me-4 or OC6H3Me2-3,5 or N2C3HMe2-3,5) yield several diastereomeric neutral or cationic half-sandwich ruthenium complexes which contain a stereogenic metal center. In one case, the absolute configuration of a trichiral ruthenium complex, viz. [Cp*Ru{eta2-Ph2PN((S)-*CHMePh)*PPh (N2C3HMe2-3,5)}Cl] is established by X-ray diffraction. The reactions of Ru3(CO)12 with the diphosphazanes (C20H12O2)PN(R)PY2 (R = CHMe2 or Me; Y2 = O2C20H12 or Y = OC6H5 or OC6H4Me-4 or OC6H4OMe-4 or OC6H4But-4 or C6H5) yield the triruthenium clusters [Ru3(CO)10{m-(O2C20H12)PN(R)PY2}], in which the diphosphazane ligand bridges two metal centres. Palladium allyl chemistry of some of these chiral ligands has been investigated. The structures of isomeric eta3-allyl palladium complexes, [Pd(eta3-1,3-R¢2-C3H3){eta2-(rac)-(O2C20H12)PN(CHMe2)PY2}](PF6) (R¢ = Me or Ph; Y = C6H5 or OC6H5) have been elucidated by high field twodimensional NMR spectroscopic and X-ray crystallographic studies.