MULTINUCLEAR NMR-STUDIES AND REACTION WITH TERT-BUTYL ISOCYANIDE OF DINUCLEAR TUNGSTEN-PALLADIUM OR MOLYBDENUM-PALLADIUM MU-ALKYLIDENE COMPLEXES - X-RAY STRUCTURE OF [PDI(MU-C(P-TOLYL)DMBA)(MU-CO)MO(CP)(CN-T-BU)(2)]

The H-1, C-13, and W-183 NMR characteristics for a series of dinuclear complexes containing a W-(mu-CR(1)R(2))-Pd moiety are reported. These compounds, derived from the reaction of the carbyne complex (Cp)(CO)(2)M(=CR), M = Mo, W, R = cyclopentenyl or p-tolyl, with a dinuclear cyclopalladated complex are shown to possess an eta(2)-bond from the cyclopentenyl or p-tolyl fragment to the metal, thus attaining an 18-electron configuration at M. The bridging carbon has its C-13 absorption at delta = 142.4-155.1. Reaction of a Mo derivative with 2 equiv of t-BuNC displaces the eta(2)-bond and affords a new complex, [PdI{mu-C(p-tolyl)-dmba}{mu-CO}Mo(Cp)(t-BuNC)(2)], whose structure in the solid state was determined by X-ray diffraction. The solution NMR data for this complex clearly show that the eta(2)-bond is no longer present.