Cationic Tungsten Oxo Alkylidene <i>N</i>-Heterocyclic Carbene Complexes via Hydrolysis of Cationic Alkylidyne Progenitors

A route to cationic tungsten alkylidyne N-heterocyclic carbene (NHC) complexes of the general formula [W(CR)X2(NHC)(tBuCN)y+B(ArF)4–] (R = tBu, C6H4-4-OMe; X Br, Cl, OTf; NHC 1,3-dimesityl-1,3-dihydro-2H-imidazol-2-ylidene, IMes; 1,3-bis(2,6-diisopropylphenyl)-1,3-dihydro-2H-imidazol-2-ylidene, IDipp; 1,3-dimesityl-4,5-dichloro-1,3-dihydro-2H-imidazol-2-ylidene, IMesCl2; y 1, 2; ArF 3,5-bis(trifluoromethyl)phenyl) is presented. Addition 1 equiv water benzylidyne and neopentylidyne results in formation corresponding oxo alkylidene complexes; however, only resulting neopentylidene were isolated as stable compounds tested selected olefin metathesis reactions. Interestingly, even though a strongly basic ligand form coordinated metal center, this bond unaffected by reaction with water. The hydrolysis represents one pathway enables synthesis complexes, which so far not easily accessible previously published procedures.