Preparation of hydrido(vinylidene)ruthenium(ii) complexes and a one-pot synthesis of Grubbs-type ruthenium carbenes

Abstract

Treatment of the hydrido(dihydrogen) compound [RuHCl(H₂)(PCy₃)₂] 1 with alkynes RCCH (R = H, Ph) afforded the hydrido(vinylidene) complexes [RuHCl(CCHR)(PCy₃)₂] 2, 3 which react with HCl or [HPCy₃]Cl to give the corresponding Grubbs-type ruthenium carbenes [RuCl₂(CHCH₂R)(PCy₃)₂] 4, 5. The reaction of 2 (R = H) with DCl, or D₂O in the presence of chloride sources, led to the formation of [RuCl₂(CHCH₂D)(PCy₃)₂] 4-d₁. Based on these observations, a one-pot synthesis of compounds 4 and 5 was developed using RuCl₃·3H₂O as the starting material. The hydrido(vinylidene) derivative 2 reacted with CF₃CO₂H and HCN at low temperatures to yield the carbene complexes [RuCl(X)(CHCH₃)(PCy₃)₂] 6, 7, of which 7 (X = CN) was characterized crystallographically. Salt metathesis of 2 with CF₃CO₂K and KI led to the formation of [RuH(X)(CCH₂)(PCy₃)₂] 8, 9. The bis(trifluoracetato) and the diiodo compounds [RuX₂(CHCH₃)(PCy₃)₂] 10, 11 as well as the new phosphine P(thp)₃12 (thp = 4-tetrahydropyranyl) and the corresponding complex [RuCl₂(CHCH₃){P(thp)₃}₂] 14 were also prepared. The catalytic activity of the ruthenium carbenes 4–7, 10, 11 and 14 in the olefin cross-metathesis of cyclopentene and allyl alcohol was investigated.