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 silyl electrophile, Me 3 SiCl. This process shows exclusive C-C coupling distinct from the previously reported phenylene-linked analogue that undergoes C-O cleavage. Further CO catenation can be engendered from 5 under mild conditions providing metallacyclobutenone complex 6 , with a C 3 O 3 organic motif derived from CO. Differences in reactivity are assigned to the nature of the arene linker, where the naphthalenediyl fragment shows a propensity for η 4 binding previously not observed for phenylene. Consistent with this hypothesis, a Mo precursor with a 1,3-cyclohexadienediyl-based linker was prepared which also showed exclusive formation of a bis(siloxy)acetylene complex and subsequent coupling of a third CO molecule.