Cyclization reactions of ruthenium vinylidene complexes

Treatment of [Ru]-C=C(Ph)C(=NPh)s (2, [Ru] = (eta(5)-C5H5)(dppe)Ru, dppe=Ph 2PCH2CH2PPh2) with ICH2CN at room temperature affords the S-alkylation prod uct [Ru]=C=C(Ph)C(=NPh)SCH2R+ (3a, R = CN). Deprotonation of 3a by n-Bu4NOH in acetone induces a novel cyclization reaction and yields the neutral fiv e-membered-ring heterocyclic complex [Ru]-C=C(Ph)C(=NPh)SCHCN (5a), which i somerizes to the 2-aminothiophene complex [Ru]-C=C(CN)SC(NHPh)=C(Ph) (6a). Treatment of 2 with organic bromides BrCH2R affords both S-alkylation produ cts (3b, R = CO2CH3; 3c, R = p-C6H4CN; 3d, R = Ph) and N-alkylation product s [Ru]=C=C(Ph)C(=S)NPhCH2R+ (4b, R = CO2CH3; 4c, R = p-C6H4CN; 4d, R = Ph) in varying ratios. Base-induced cyclization of a mixture of 3b and 4b occur s only for the 3b component to afford [Ru]-C=C(Ph)C(=NPh)SCHCO2CH3 (5b), wh ereas cyclization of a mixture of 3c and 4c occurs for both complexes, yiel ding 5c and the pyrrole-2-thione complex [Ru]-C=C(Ph)C(=S)N(Ph)CH(p-C6H4CN) (7c), respectively. Cyclization of a 3d-4d mixture occurs only for 4d to a fford [Ru]-C=C(Ph)C(=S)NPhCHPh (7d). The structures of 6a and 7c were deter mined by single-crystal X-ray diffraction analysis.