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′ = CN^tBu 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}(CN^tBu)[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.