Chemistry of phosphido-bridged palladium(I) dimers. .eta.2-Pd-H-P interactions: a new bonding mode for secondary phosphines

The preparation of two new and unusual cationic Pd(I) dimeric complexes, containing bridging PBu2t and terminal PHBu2t ligands, is described. One of these, [Pd2(mu-PBu2t)(mu-PHBu2t)(PHBu2t)2]+, [2]+, contains a Pd-H-P bridging unit, the first example of this type of bonding. A second, [Pd2(mu-PBu2t) (CO) 2(PHBu2t)2]+, [3]+, represents a rare example of a Pd(I) complex with terminal CO ligands. Electrochemical, ESR, one-and two-dimensional multinuclear NMR, and X-ray crystallographic studies have been carried out on both [2]+ and [3]+. Relevant crystallographic parameters for the two triflate complexes: compound [2a]+ triclinic space group P1, a = 10.245(1) angstrom, b = 10.739(1) angstrom, c = 22.624(3) angstrom, a = 79.816(9)-degrees, beta = 87.876(10)-degrees, gamma = 68.266(8)-degrees, V = 2274.7(5) angstrom3, z = 2; compound [3a]+ orthorhombic, space group Pbca, a = 21.910(7) angstrom, b = 21.120(3) angstrom, c = 16.625(8) angstrom, V = 7707(4) angstrom3, Z = 8.