The five-coordinate palladium(II) and platinum(II) complexes [M(PP(3))Cl]Cl [M = Pd (1), Pt (2)] (PP(3) = tris[2-(diphenylphosphino)ethyl]phosphine) were prepared by interaction of aqueous solutions of MCl(4)(2-) salts with PP(3) in CHCl(3). Complexes 1 and 2 undergo facile chloro substitution reactions with KCN in 1:1 and 1:2 ratios to afford complexes [M(PP(3))(CN)]Cl [M = Pt (3)] and [M(PP(3))(CN)](CN) [M = Pd (4), Pt (5)] possessing M-C bonds, both in solution and in the solid state. The reaction of 1 and 2 with SnCl(2) in CDCl(3) occurs with insertion of SnCl(2) into M-Cl bonds leading to the formation of [M(PP(3))(SnCl(3))](SnCl(3)) [M = Pd (6), M = Pt (7)]. The isolation as solids of complexes 6 and 7 by addition of SnCl(2) to the precursors requires the presence of PPh(3) which activates the cleavage of M-Cl bonds, favors the SnCl(2) insertion, and does not coordinate to M in any observable extent. Solutions of 6 in CDCl(3) undergo tin dichloride elimination in higher proportion than solutions of 7. The reaction of complexes 1 and 2 with SnPh(2)Cl(2) leads to [M(PP(3))Cl](2)[SnPh(2)Cl(4)] [M = Pd (8)]. Complexes 2, 5, 7, and 8 were shown by X-ray diffraction to contain distorted trigonal bipyramidal monocations [M(PP(3))X](+) [M = Pt, X = Cl(-) (2), X = CN(-) (5), X = SnCl(3)(-) (7); M = Pd, X = Cl(-) (8)], the central P atom of PP(3) being trans to X in axial position and the terminal P donors in the equatorial plane of the bipyramids. The "preformed" catalyst 7 showed a relatively high aldehyde selectivity compared to most of the platinum catalysts.

The interaction of sodium tetrachloropalladate(II) with the potentially tridentate aminophosphine bis [2-(diphenylphosphino)ethyl]amine (PNHP) in 1 : 1 molar ratio leads to the formation of the four-coordinate complex [Pd(PNHP)Cl]Cl (1). Complex 1 undergoes chloro substitution reactions with NaX (X ¼ Br, I), CuCl, AgNO 3 , the amino acid N-acetyl-L-cysteine (AcCysSH) and the tripeptide reduced glutathione GS (9)]. However, gold(I) induces abstraction of the aminophosphine from the ionic complexes 1 and 2 to produce the neutral compounds Au 2 (PNHP)X 2 [X ¼ Cl (5), Br (6)]. The dinuclear complex Au 2 (PN(NO)P)Cl 2 (5a), containing the ligand bis[2-(diphenylphosphino)ethyl]nitrosylamine, was formed by reaction of 4 with gold(I) in the presence of traces of nitrosyl chloride. Addition of one molar equivalent of PNHP to 1 results, by a ring-opening process, in the formation of [Pd(PNHP) 2 ]Cl 2 (7) in which the palladium is five-coordinate. The ionic complexes 1, 2 and 4 were shown by X-ray diffraction to be distorted square-planar and complex 2 has a N-HÁ Á ÁBr bond of 2.371 + A with the ligand adopting a boat conformation. The X-ray crystal structure of the novel neutral compound 5a shows linear P-Au-Cl arrangements with intermolecular AuÁ Á ÁAu interactions of 3.0412(9) + A.

No abstract