Palladium(II) and platinum(II) derivatives with N,O ligands

The preparation of a series of Pd(II) and Pt(II) derivatives with three N,O hybrid ligands 1-(2-pyridyl)ethyldiphenylphosphine oxide, L-1; (2-pyridyl) methyldiphenylphosphine oxide, L-2 and 2-pyridyldiphenylphosphine oxide, L- 3 is described. Depending on the ligand to metal molar ratio, either 1:1 [L MCl2]{[(LPdCl2)-Pd-1] 1, [(LPdCl2)-Pd-2] 2, [(LPdCl2)-Pd-3] 3, [(LPtCl2)-Pt -1] 4} or 2:1 [L2MCl2] {[(L2PdCl2)-Pd-1] 5, [(L2PdCl2)-Pd-2], 6, [(L2PtCl2) -Pt-1] 7} adducts are obtained. In addition, an ionic species [(L2Pd)-Pd-1] [PF6](2) 8, has been isolated by treatment of complex 5 with AgPF6. The str uctures in the solid state of compounds 5b . MeOH . H2O, 6 . MeOH and 4 . C H2Cl2 have been solved by X-ray diffraction. The structures of trans-[(L2Pd Cl2)-Pd-1] 5b (one of the diastereomers of 5) and trans-[(L2PdCl2)-Pd-2] 6 are rather different, the former being a chiral molecule (R,R enantiomer) w ith a C-2 axis perpendicular to the plane of the metal, the latter, 6, bein g a centrosymmetric molecule. In both the species the ligand is bonded thro ugh the nitrogen atom. In complex [(LPtCl2)-Pt-1] 4, the ligand is coordina ted through the N and O atoms to form a six-membered ring which adopts a bo at-like conformation. The structure reveals a fairly short interaction betw een one hydrogen atom of the Me group in an axial position and the platinum atom, Pt ... H 2.69 Angstrom. Short contacts Pd ... H are also observed in the structures of compounds 5b and 6. Some aspects of the reactivity of th e new species are discussed.