Reactions of ruthenium acetylide complexes with benzylidenemalonitrile †

Abstract

Reactions of [RuCp(L)(L′)(CCPh)] (Cp = η5-C5H5; L = PPh3, L′ = P(OMe)3 1a; LL′ = dppe = Ph2PCH2CH2PPh2 1b; L = PPh3, L′ = CNtBu 1c) with H(Ph)CC(CN)2 gave the cyclobutenyl complexes [RuCp(L)(L′){CC(Ph)CH(Ph)C(CN)2}] 2a, 2b and 2c which readily transform to the butadienyl complexes [RuCp(L)(L′){C[C(CN)2]C(Ph)CH(Ph)}] 3a, 3b and 3c, respectively. Thermolysis of 3a in benzene afforded the allylic complex [RuCp{P(OMe)3}[η3-C[=C(CN)2]C(Ph)CH(Ph)}] 4 in high yield. Reaction of 4 with tBuNC gave [RuCp{P(OMe)3}(CNtBu)[η1-C[C(CN)2]C(Ph)CH(Ph)}] 5. Treatment of 1a with Cl(Ph)CC(CN)2 afforded the neutral vinylidene phosphonate complex [RuCp(PPh3){P(O)(OMe)2}{CC(Ph)C(Ph)C(CN)2}] 6. Reactions of 1b and 1c, both lacking phosphite ligands, with Cl(Ph)CC(CN)2 gave the cationic vinylidene complexes [RuCp(L)(L′){CC(Ph)C(Ph)C(CN)2}]+ 7b and 7c, respectively. Treatment of 1a with ICH2CN afforded [RuCp(PPh3){P(OMe)3}{CC(Ph)CH2CN}]I 8a. In the presence of acid complex 8a decomposes to give the acyl complex [RuCp(PPh3){P(OMe)3}(COCH2Ph)] 10. The structures of 3a, 4, 6 and the latter complex have been determined by single-crystal X-ray diffraction analysis.