ELECTROPHILIC ATTACK OF GROUP-11 AND GROUP-12 METAL FRAGMENTS ON THE DINUCLEAR ANIONS [M(2)(MU-SIGMA-C(2)PH)(CO)(4)(ETA-C5H5)(2)](-) (M=MO, W) - CRYSTAL-STRUCTURE OF THE TRANSVERSALLY BRIDGED ALKYNE COMPLEX [W-2(MU-PHC(2)AUPPH(3))(CO)(4)(ETA-C5H5)(2)]

The dinuclear anions [M(2)(mu-o:C(2)Ph)(CO)(4)(eta-C5H5)(2)](-) (M = Mo, W) react with gold halides ClAuPR(3) (R = Ph, Me) in tetrahydrofuran to yield the mu-alkyne bonded complexes [M(2)(mu PhC(2)AuPR(3))(CO)4(eta-C5H5)2] [M = Mo, R = Ph (1a), R = Me (2a); M = W, R = Ph (1b), R = Me (2b)] in good yield. The structure of 1b has been determined by X-ray diffraction methods. The crystals are monoclinic, space group P2(1)/c with Z = 4 in a unit cell of dimensions alpha = 8.417(4) Angstrom, b = 16.386(6) Angstrom, c = 25.352(9) Angstrom, beta = 90.55(2)degrees. The structure has been solved from diffractometer data by direct and Fourier methods and refined by full-matrix least-squares on the basis of 3865 observed reflections to R and R(w) values of 0.0314 and 0.0362, respectively. The complex displays a W2C2 tetrahedral core with W-W and the C-C bond distances of 2.958(1) and 1.387(15) Angstrom, respectively. The reaction between the dinuclear anions and HgCl2 leads to a new class of pentametallic symmetric mercury derivatives where the mercury atom forms two Hg-C(mu-alkyne) bonds bridging two cluster units.