Carbon dioxide cleavage across a tungsten-alkylidyne bearing a trianionic pincer-type ligand.

The cleavage of carbon dioxide by the tungsten alkylidyne [CF3-ONO]W[triple bond, length as m-dash]CCtBu(THF)2 (1) {where CF3-ONO = (MeC6H3[C-(CF3)2O])2N3-}, is reported. Splitting of CO2 yields the tungsten oxo ketene complex [CF3-ONO]W(O){(CH3)3CC[double bond, length as m-dash]C[double bond, length as m-dash]O} (6). The proposed pathway occurs through initial cycloaddition of W[triple bond, length as m-dash]C and C[double bond, length as m-dash]O bonds to generate a heterometallacyclobutene, which then rearranges to yield W[triple bond, length as m-dash]O and C[double bond, length as m-dash]C bonds. Complex 6 was characterized by multinuclear NMR, IR, and single crystal X-ray diffraction.