CYCLOMETALATED COMPLEXES OF PALLADIUM(II) WITH THE DIPHOSPHINES TRANS-PH2 PCH=CHPPH2, CIS-PH2PCH=CHPPH2 AND PH2P(CH2)4PPH2 - THE X-RAY CRYSTAL-STRUCTURE OF [(PD[2,4-ME2C6H2C(H)=NCY])2(MU-PH2P(CH2)4PPH2)(MU-CL)2]

Treatment of 2,4-Me2C6H3C(H)=NCy (a) or 2,3-(MeO)2C6H3C(H)=NCy (b) (Cy = cyclohexyl) with palladium(II) acetate gave the cyclometallated acetato-bridged complexes la and lb. These were converted into the analogous halide-bridged complexes by reaction with NaX (2a, 2b, X = Cl; 3a, 3b, X = Br; 4a, 4b, X = 1). The halide-bridged dimers react: (a) with trans-Ph2PCH=CHPPh2 (trans-dppe) and Ph2P(CH2)4PPh2 (dppb) in a dimer/diphosphine 1:1 molar ratio to give the dinuclear phosphine-bridged complexes 5a-7a, 5b-7b (trans-dppe) and 8a-10a, 8b-10b (dppb); and (b) with cis-Ph2PCH=CHPPh2 (cis-dppe) or Ph2P(CH2)4PPh2 (dppb), in a dimer/diphosphine 1:2 molar ratio, and NH4PF6, to give the mononuclear cyclometallated species 11a, 11b (cis-dppe), or 12a and 12b (dppb). The Structure of 8a is described. This is the first structurally characterised dinuclear palladium(II) complex with two cyclometallated moieties bounded through a diphosphine ligand. The crystals are monoclinic, space group P2(1)/n with a = 1084.1(7), b = 3067.7(28), c = 1181.9(10) pm, beta = 114.22(6)-degrees, U 3.585(5) nm3, Z = 2, R = 0.0731 and R(w) = 0.0602 for 3970 independent reflections.