Vinyl and carbene ruthenium(ii) complexes from hydridoruthenium(ii) precursors

Abstract

The reactions of the hydrido compounds [RuHCl(CO)(L)₂] {L = PiPr₃ (1), PCy₃ (2)} with HCCR (R = H, Ph, tBu) afforded by insertion of the alkyne into the Ru–H bond the corresponding vinyl complexes [RuCl(CHCHR)(CO)(L)₂], 3–8, which upon protonation with HBF₄ gave the cationic five-coordinated ruthenium carbenes [RuCl(CHCH₂R)(CO)(L)₂]BF₄, 9–14. Subsequent reactions of the carbene complexes with PR₃ (R = Me, iPr) and CH₃CN led either to deprotonation and re-generation of the vinyl compounds or to cleavage of the ruthenium-carbene bond and the formation of the six-coordinated complexes [RuCl(CO)(CH₃CN)₂(PiPr₃)₂]BF₄, 17, and [RuH(CO)(CH₃CN)₂(PiPr₃)₂]X, 18a,b. The acetato derivative [RuH(κ²-O₂CCH₃)(CO)(PCy₃)₂], 19, also reacted with acetylene and phenylacetylene by insertion to yield the related vinyl complexes [Ru(CHCHR)(κ²-O₂CCH₃)(CO)(PCy₃)₂], 20, 21, of which that with R = H was protonated with HBF₄ to yield the corresponding cationic ruthenium carbene 22. With [RuHCl(H₂)(PCy₃)₂], 25, as the starting material, the five-coordinated chloro(hydrido)ruthenium(II) compounds [RuHCl(PCy₃)(dppf)], 26 (dppf = [Fe(η⁵-C₅H₄PPh₂)₂]), [RuHCl{Sb(CH₂Ph)₃}(PCy₃)₂], 27, and [RuHCl(CH₃CN)(PCy₃)₂], 30, were prepared. The reactions of 27 with HCCR (R = H, Ph) gave the hydrido(vinylidene) complexes [RuHCl(CCHR)(PCy₃)₂], 28 and 29, whereas treatment of 30 with HCCPh afforded the vinyl compound [RuCl(CHCHPh)(CH₃CN)(PCy₃)₂], 31. The molecular structures of 11 (R = tBu, L = PiPr₃) and 26 were determined crystallographically.