Stepwise reduction of the acetonitrile ligand in [Tp'(CO)(RC = CR')W(N = CMe)][BF4] has been accomplished with sequential addition of nucleophiles and electrophiles to the carbon-nitrogen triple bond. Intermediate metal complexes containing coordinated azavinylidene, imine, amide, and amine nitrogen donor ligands have been isolated and characterized. Nucleophilic addition to the imine complexes is highly stereoselective. Acidification of the amine complex in acetonitrile forms the free ammonium salt, and solvent coordination regenerates the acetonitrile adduct.