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

Treatment of the complex [W(CO)5[PPh2(CS2Me)]] (2) with [Pd(PPh3)4] (1) affords binuclear complexes such as
anti-[(Ph3P)2Pd[μ-η1,η2-(CS2Me)PPh2]W(CO)5] (3), syn-[(Ph3P)2Pd[μ-η1,η2-(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-η1,η2-(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-η1,η2-[CS2(CH2)nCN]PPh2]W(CO)5] (n = 1, 9a; n = 2, 9b). Similar configurational products syn-[(Ph3P)2Pd[μ-η1,η2-(CS2R)PPh2]W(CO)5] (R
= C2H5, C3H5, C2H4OH, C3H6CN, 11a−d) are synthesized by the reaction of Pd(PPh3)4 with [W(CO)5[PPh2(CS2R)]] (R = C2H5, C3H5, C2H4OH, C3H6CN, 10a−d). Although complexes 11a−d 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)°.