Synthesis and structure of dinuclear palladium(II) complexes with bridging hydride and phosphide ligands

The reaction of Pd(dppf)(Ph)(I) (1, dppf = Ph2PC5H4FeC5H4PPh2) with 1.5 equiv of PPH2H leads to the formation of the Pd(II) dinuclear complex Pd2I2(mu-dppf)(mu-H)(mu-PPh2) (2) and the phosphines PPh3 and dppf. The reaction of 1 with 1 equiv of PCy2H (Cy = cyclo-C6H11) slowly gives Pd2I2(mu-dppf)(mu-H)(mu-PCy2) (3). Complex 2 reacts further with PPh2H to give the known [Pd(mu-PPh2)(I)(PPh2H)](2) (4). Reaction of Pd(dcpm)(Ph)(I) (dcpm = Cy2PCH2PCy2) with PPh2H gives [Pd-2(PPh2H)(2)(mu-dcpm)(mu-PPh2)][I] (5). Treatment of Pd(dmpe)(Me)(Cl) (dmpe = Me2PCH2CH2PMe2) with AgOTf and PPh2H gives [Pd(dmpe)(mu-PPh2)](2)[OTf](2) (6, OTf = OSO2CF3) as well as a small amount of [Pd-2(dmpe)(2)(mu-H)(mu-PPh2)][OTf](2) (7). Slow decomposition of [Pd(dmpe)(Me)(PCy2H)](+), prepared by the reaction of Pd(dmpe)(Me)(Cl), AgOTf, and PCy2H, gives [Pd-2(dmpe)(2)(mu-H)(mu-PCy2)][OTf](2) (8), which was also prepared from Pd(dmpe)Cl-2, AgOTf, Pd(dmpe)(dba) (dba = dibenzylideneacetone), and PCy2H. Complexes 3, 4, 5, and 8 were structurally characterized by X-ray crystallography.