HETERODINUCLEAR BIS(DIPHENYLPHOSPHINO)METHANE-BRIDGED MOLYBDENUM(D6)-PALLADIUM(D8) COMPLEXES WITH DATIVE MO-]PD BONDING

Investigation of the reaction between (t-BuNC)2PdCl2 and mer-Mo(dpm-P,P')(dpm-P)(CO)3 (dpm = bis-(diphenylphosphino)methane) has produced two complexes that combine a d6 and a d8 metal center. The reaction in dichloromethane yields green [(t-BuNC)(OC)3Mo(mu-dpm)2PdCl]Cl (6). Addition of 1 equiv of [(n-Bu)3(n-Pr)N]I and ammonium hexafluorophosphate to [(t-BuNC)(OC)3Mo(mu-dpm)2PdCl]CI (6) yields golden brown [(t-BuNC)(OC)3Mo(mu-dpm)2PdI](PF6) (7). Orange-brown plates of [(t-BuNC)(OC)3Mo(mu-dpm)2PdI](PF6). 0.5Et2O.H2O form in the tetragonal space group I42mBAR with a = 22.822(4) angstrom and c = 27.013(7) angstrom at 130 K with Z = 8. Refinement of 3764 reflections and 388 parameters yielded R = 0.049 and R(w) = 0.053. The structure consists of a seven-coordinate molybdenum atom with a nearly octahedral trans-P2Mo(CO)3(CNBu-t) core that is connected to a (P2PdI)+ unit through the two dpm bridges. The Mo-Pd bond length is 2.870(2) angstrom. Reaction of (t-BuNC)2PdCl2 and mer-Mo(dpm-P,P')(dpm-P)(CO)3 in benzene yields dark brown crystals of (t-BuNC)-(OC)ClMo(mu-CO)(mu-dpm)2PdCl (8). Red-brown blocks of (t-BuNC)(OC)ClMo(mu-CO)(mu-dpm)2PdCl.2CHCl3 form in the monoclinic space group P2(1)/c with a = 11.825(6) angstrom, b = 21.508(12) angstrom, c = 24.441(13) angstrom, and beta = 100.77(4)-degrees at 130 K with Z = 4. Refinement of 6413 reflections and 329 parameters yielded R = 0.069 and R(w) = 0.061. This structure parallels the former with the exceptions that the terminal ligand bound to palladium is now a chloride ligand and one of the carbon monoxide ligands on molybdenum has been replaced by a terminal chloride ligand. The Mo-Pd bond length is 2.826(2) angstrom. The structure of the previously reported (OC)3(NC)Mo(mu-dpm)2Pd-(CN) has also been examined. (OC)3(NC)Mo(mu-dpm)2Pd(CN).CH3OH.0.5H2O crystallizes in the triclinic space group P1BAR with a = 12.486(3) angstrom, b = 15.213(6) angstrom, c = 16.511(7) angstrom, a = 11 6.85(2)-degrees, beta = 96.17(2)-degrees, and gamma = 95.40(2)-degrees at 130 K with Z = 2. Refinement of 4918 reflections and 268 parameters yielded R = 0.083 and R(w) = 0.089. The structure consists of a trans-Mo(mu-dpm)2Pd core with three terminal carbonyl groups and a cyanide ligand bound to molybdenum and a terminal cyanide ligand attached to palladium. The Mo-Pd distance is 2.926(2) angstrom.