ELECTRON-DONOR ABILITY OF THE UNSATURATED DIMANGANESE HYDRIDES [MN2(MU-X)(MU-H)(CO)6(MU-DPPM)] (X = H, AUPPH3 DPPM = PH2PCH2PPH2) - X-RAY CRYSTAL-STRUCTURES OF [MN2(MU-AG(CLO4)PPH3)(MU-H)2(CO)6(MU-DPPM)] AND [MN2(MU-AUPPH3)2(MU-H)(CO)6(MU-DPPM)][PF6].C7H8

The electron-donor ability of the unsaturated dimanganese hydrides [Mn2(mu-H)2(CO)6(mu-dppm)] and [Mn2(mu-AuPPh3)(mu-H)(CO)6(mu-dppm)] (dppm = Ph2PCH2PPh2) is shown by the reactions of the former with [AuPPh3]+ or [Ag(ClO4)PPh3] and those of the Mn2Au cluster with H+ or [AuPPh3]+. All these reactions result in the coordination of the unsaturated dimanganese moiety to the acidic species, thus affording the new unsaturated heterometallic clusters [Mn2(mu-AuPPh3)(mu-H)2(CO)6(mu-dppm)]A (A- = BF4-, PF6-), [Mn2{mu-Ag(ClO4)PPh3}(mu-H)2(CO)6(mu-dppm)], and [Mn2(mu-AuPPh3)2(mu-H)(CO)6(mu-dppm)][PF6].The last two compounds display dynamic behavior in solution, and their crystal structures have been solved by X-ray diffraction methods. The manganese-silver cluster crystallizes in the triclinic space group P1BAR (a = 13.308 (2) angstrom, b = 14.660 (1) angstrom, c = 14.738 (1) angstrom, alpha = 113.90 (1)-degrees, beta = 91.19 (4)-degrees, gamma = 109.08 (1)-degrees, V = 2445 (1) angstrom3, Z = 2). The structure was refined to R = 0.031 (R(w) = 0.037) for 3682 reflections with I greater-than-or-equal-to 3-sigma(I). The triangular metal core is characterized by a short Mn-Mn distance (2.740 (1) angstrom) and long Mn-Ag ones (average 2.945 (1) angstrom), and it is triply bridged by one hydrido ligand; in addition, the Mn-Mn edge is bridged by a second hydrogen atom and the dppm ligand. The manganese-gold cluster (toluene solvate) crystallizes in the monoclinic space group P2(1)/a (a = 17.539 (9) angstrom, b = 25.532 (9) angstrom, c = 17.888 (3) angstrom, beta = 118.02 (5)-degrees, V = 7158 angstrom3, Z = 4). The structure was refined to R = 0.051 (R(w) = 0.057) for 2317 reflections with I greater-than-or-equal-to 3-sigma(I). The cation contains an asymmetrical butterfly Mn2Au2 core with a somewhat short Mn-Mn distance (2.864 (5) angstrom). The hydrido ligand could not be located, but it is deduced that it must be triply bridging the Mn2Au(2) face by consideration of the bond angles involved and the significant differences between MnAu(2) (average 2.806 (4) angstrom) and MnAu(1) (average 2.684 (4) angstrom), this being in agreement with the variable-temperature NMR data in solution.