CHEMISTRY OF DI-METAL AND TRI-METAL COMPLEXES WITH BRIDGING CARBENE OR CARBYNE LIGANDS .26. REACTIONS OF THE COMPOUNDS [PTW(MU-SIGMA-ETA-3-CH(C6H4ME-4))(CO)2(PR3)2(ETA-C5H5)][BF4] (PR3 = PME3, PME2PH, OR PMEPH2) AND [PTW(MU-SIGMA-ETA-3-C(ME)C6H4ME-4)(CO)2(PME3)2(ETA-C5H5)]-[SO3CF3] WITH NUCLEOPHILES - X-RAY CRYSTAL-STRUCTURE OF [PTW(MU-H)-(MU-CH(C6H4ME-4))(CO)2(PME3)2(ETA-C5H5)])