Molybdenum-Mediated Coupling of Carbon Monoxide to a C-3 Product on a Single Metal Site

:the synthesis and characterization of a series of naphthalenediyl-diphosphine molybdenum complexes are reported.A novel dicarbonyl-Mo complex (3) converts to a bis(siloxy)acetylene complex (5) upon reduction and treatment with a silylelectrophile, Me3SiCl. This process shows exclusive C-C coupling distinct from the previously reported phenylene-linked analoguethat undergoes C-O cleavage. Further CO catenation can be engendered from5under mild conditions providingmetallacyclobutenone complex6, with a C3O3organic motif derived from CO. Differences in reactivity are assigned to thenature of the arene linker, where the naphthalenediyl fragment shows a propensity for eta 4binding previously not observed forphenylene. Consistent with this hypothesis, a Mo precursor with a 1,3-cyclohexadienediyl-based linker was prepared which alsoshowed exclusive formation of a bis(siloxy)acetylene complex and subsequent coupling of a third CO molecule.