Synthesis of N-bonded enolatoruthenium (II) by oxidative addition of alkyl cyanocarboxylate to a ruthenium (0) complex

摘要

Reaction of a zero-valent ruthenium complex [Ru(cot)(cod)] 1 (cod = 1, 5-cyclooctadiene; cot = 1, 3, 5-cyclooctatriene) with alkyl cyanoacetate in the presence of mono- and bi-dentate tertiary phosphines gave a series of hydrido (enolato)-ruthenium (II) complexes: mer-[RuH(NCCHCO_2Et)(NCCH_2CO_2Et)(PPh_3)_3] 2; trans-[RuH(NCCHCO_2Et)(cod)(dppe)] 3 (dppe = Ph_2PCH_2CH_2PPh_2); trans-[RuH(NCCR~1CO_2R~2)(dppe)_2] (R~1 = H, R~2 = Et 4a; or Pr~i 4b; R~1 = Me, R~2 = Et 4c) and trains-[RuH(NCCMeCO_2Et)(PMePh_2)_4] 5. The molecular structure of 3 shows that the enolato ligand co-ordinates to the ruthenium centre via the cyano group in an octahedral geometry. These hydrido-(enolato)ruthenium (II) complexes catalyse Michael and Knoevenagel reactions under neutral and mild conditions.