A convenient route to six-membered heterocyclic carbene complexes: Reactions of aminoallenylidene complexes with 1,3-bidentate nucleophiles

Complexes containing a heterocyclic carbene ligand such as pyrimidinylidene, pyrazolo[1,5a]pyrimidinylidene, and thiazinylidene complexes are conveniently accessible by reaction of pentacarbonyl dimethylaminoallenylidene chromium complexes, [(CO)5CrCCC(R)OMe] (R = OMe, Ph) with 1,3-bidentate nucleophiles like amidines, guanidine, amino-5-methylpyrazole, or thioacetamide.