DPPM-ASSISTED SYNTHESIS AND REACTIVITY OF BIMETALLIC M-MO,M-W,M-CO, AND M-MN (M=PT,PD) COMPLEXES - CRYSTAL-STRUCTURE OF [(ETA-2-DPPM)PT(MU-DPPM)W(CO)2CP][PF6].CH2CL2 (DPPM=PH2PCH2PPH2)

Heterometallic carbonyl complexes and clusters were prepared by reacti on of dppm (dppm = Ph2PCH2PPh2) with linear trinuclear chain complexes trans-[Pt(or Pd){m(CO)}2(NCPh)2] (M(CO) = MO(CO)3CP, W(CO)3CP, Mn-(CO )5,CO(CO)4). The reaction of trans-[Pd{M(CO)}2(NCPh)2]with dppm afford ed products having very different structures depending on the nature o f the metal carbonyl fragment m(CO), as exemplified by the synthesis o f the cationic bimetallic complexes [Pd(mu-dppm)2m]+ (M = MO(CO)2CP, 1 +; M = W(CO)2Cp, 2+), the neutral bimetallic [ClPd(mu-dppm)2Mn(CO)3] ( 3a), and the trinuclear cluster [PdCo2(CO)5(mu-dppm)2] (6). In contras t, the reaction of the Pt precursor trans-[Pt{M(CO)}2(NCPh)2] with dpp m is much more selective, giving only bimetallic ionic complexes [(eta 2-dppm)Pt(mu-dppm)m] [m(CO)] (m = MO(CO)2Cp, 7a; m = W(CO)2CP, 8a; m = Mn(CO)4, 9; M = CO(CO)3, 10). Exchange of the anions in 7a and 8a wit h PF6- afforded [(eta2-dppm)Pt(mu-dppm)MO(CO)2CP]-[PF6] (7b) and [(eta 2-dppm)Pt(mu-dppm) W(CO)2CP][PF6] (8b), respectively, which are more s oluble. The solid-state structure of the dichloromethane solvate of 8b has been determined by a single-crystal X-ray analysis. It crystalliz es in the triclinic space group PI with Z = 1 in a unit cell of dimens ions a = 11.257(7) angstrom, b = 12.691(6) angstrom, c = 11.055(6) ang strom, alpha = 112.20(3)-degrees, beta = 101.68(3)-degrees, and gamma = 76.71(4)-degrees. The structure has been solved from diffractometer data by Patterson and Fourier methods and refined by full-matrix least squares on the basis of 5157 observed reflections to R and R(w) value s of 0.0372 and 0.0494, respectively. In the structure of the chiral c ation of 8b, a dppm chelates the Pt atom and the other bridges the W a nd Pt metals, which are linked by a rather long metal-metal bond [2.90 2(2) angstrom]. Compounds 7b and 8b react with NaBH4 to give the hydri do complexes [(eta1-dppm)(H)Pt(mu-dppm)m] (m = MO(CO)2CP, 11; M = W(CO )2CP, 12) in which the hydride ligand occupies a position trans to pho sphorus. The situation is different for [(eta1-dppm)(H)Pt(mu-dppm)CO(C O)3] (13), obtained from 10, in which the hydride ligand is cis to the Pt-bound phosphorus atoms. The structures of all these complexes are consistent with the IR and H-1, P-31, and Pt-195 spectroscopic data.