Cationic phthaloylcobalt complexes 3-7 have been prepared by reaction of chlorocobalt phthaloyl complex 1 with AgBF, followed by treatment with the appropriate ligand. Reaction of these cationic complexes with alkynes produced naphthoquinones, and the mechanistic nature of the results is discwd. The cationic cobalt complex 6 with a chelating diphos ligand was found to rapidly give high yields of substituted naphthoquinones on treatment with ...