Multinuclear NMR studies and reaction with tert-Butyl Isocyanide of Dinuclear Tungsten- or Molybdenum-Palladium Micro-Alkylidene Complexes. X-ray structure of [PdI{Micro-C(p-tolyl)dmba}{Micro-CO}Mo(Cp)(CN-t-Bu)2]

Abstract

The lH, 13C, and 183W NMR characteristics for a series of dinuclear complexes containing a W-(Micro-CR1R2)-Pd moiety are reported. These compounds, derived from the reaction of the carbyne complex (Cp)(C0)2M(=CR), M = Mo, W, R = cyclopentenyl or p-tolyl, with a dinuclear cyclopalladated complex are shown to possess an y2-bond from the cyclopentenyl or p-tolyl fragment to the metal, thus attaining an 18-electron configuration at M. The bridging carbon has its 13C absorption at delta = 142.4-155.1. Reaction of a Mo derivative with 2 equiv of t-BuNC displaces the y2-bond and affords a new complex, [PdI{Micro-C(p-tolyl)-dmba){Micro-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 y2-bond is no longer present.