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Synthesis and Structural Characterization of Configurational Isomers of Tungsten−Palladium Complexes with Bridging Diphenyl(dithioalkoxycarbonyl)phosphine as a Ligand and Phosphine Transfer from Tungsten to Palladium

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posted on 19.05.2000, 00:00 by Kuang-Hway Yih, Gene-Hsiang Lee, Yu Wang
Treatment of the complex [W(CO)5[PPh2(CS2Me)]] (2) with [Pd(PPh3)4] (1) affords binuclear complexes such as anti-[(Ph3P)2Pd[μ-η12-(CS2Me)PPh2]W(CO)5] (3), syn-[(Ph3P)2Pd[μ-η12-(CS2Me)PPh2]W(CO)5] (4), and trans-[W(CO)4(PPh3)2] (5). In 3 and 4, respectively, the W and Pd atoms are in anti and syn configurations with respect to the P−CS2 bond of the diphenyl(dithiomethoxycarbonyl)phosphine ligand, PPh2(CS2Me). Complex 3 undergoes extensive rearrangement in CHCl3 at room temperature by transfer of a PPh3 ligand from Pd to W, eliminating [W(CO)5(PPh3)] (7), while the PPh2CS2Me ligand transfers from W to Pd to give [[(Ph3P)Pd[μ-η12-(CS2Me)PPh2]]2] (6). In complex 6, the [Pd(PPh3)] fragments are held together by two bridging PPh2(CS2Me) ligands. Each PPh2(CS2Me) ligand is π-bonded to one Pd atom through the CS linkage and σ-bonded to the other Pd through the phosphorus atom, resulting in a six-membered ring. Treatment of Pd(PPh3)4 with [W(CO)5[PPh2[CS2(CH2)nCN]]] (n = 1, 8a; n = 2, 8b) in CH2Cl2 affords syn-[(Ph3P)2Pd[μ-η12-[CS2(CH2)nCN]PPh2]W(CO)5] (n = 1, 9a; n = 2, 9b). Similar configurational products syn-[(Ph3P)2Pd[μ-η12-(CS2R)PPh2]W(CO)5] (R = C2H5, C3H5, C2H4OH, C3H6CN, 11ad) are synthesized by the reaction of Pd(PPh3)4 with [W(CO)5[PPh2(CS2R)]] (R = C2H5, C3H5, C2H4OH, C3H6CN, 10ad). Although complexes 11ad have the same configuration as 9a,b, the SR group is oriented away from Pd in the former and near Pd in the latter. In these complexes, the diphenyl(dithioalkoxycarbonyl)phosphine ligand is bound to the two metals through the CS π-bonding and to phosphorus through the σ-bonding. All of the complexes are identified by spectroscopic methods, and the structures of complexes 3, 6, 9a, and 11d are determined by single-crystal X-ray diffraction. Complexes 3, 9, and 11d crystallize in the triclinic space group P1̄ with Z = 2, whereas 6 belongs to the monoclinic space group P2/c with Z = 4. The cell dimensions are as follows:  for 3, a = 10.920(3) Å, b = 14.707(5) Å, c = 16.654(5) Å, α = 99.98(3)°, β = 93.75(3)°, γ = 99.44(3)°; for 6, a = 15.106(3) Å, b = 9.848(3) Å, c = 20.528(4) Å, β = 104.85(2)°; for 9a, a = 11.125(3) Å, b = 14.089(4) Å, c = 17.947(7) Å, α = 80.13(3)°, β = 80.39(3)°, γ = 89.76(2)°; for 11d, a = 11.692(3) Å, b = 13.602(9) Å, c = 18.471(10) Å, α = 81.29(5)°, β = 80.88(3)°, γ = 88.82(1)°.