CHEMISTRY OF DI- AND TRI-METAL COMPLEXES WITH BRIDGING CARBENE OR CARBYNE LIGANDS. PART 8. SYNTHESIS OF THE TRIMETAL COMPOUNDS (M(W(μ-CC6H4ME-4)(CO)2(η-C5H5))2) (M = NI, PD, OR PT) AND CRYSTAL STRUCTURES OF THE PLATINUM AND NICKEL COM