Fluorophosphine complexes of ruthenium and osmium. Part 5. Alkene hydrogenation catalysed by ruthenium(II) complexes

Abstract

The effectiveness of several hydridoruthenium complexes as homogeneous hydrogenation catalysts for oct-1 -ene has been studied. The activity, which decreases in the order [RuCl(H)(PPh₃)₃]cis-[RuH₂(PPh₃)₄] > cis-[ RuH₂{PF₂(NMe₂)}(PPh₃)₃] > cis-[RuH₂(PF₃)(PPh₃)₃] > cis-[RuH₂{PF₂(NMe₂)}₂(PPh₃)₂] > cis-[RuH₂(PF₃)-{PF₂)(NMe₂)}(PPh₃)₂] > cis-[RuH₂(PF₃)₂(PPh₃)₂] is related to the ease of PPh₃ dissociation from these six-co-ordinate complexes. The monomeric complexes cis-[RuCl₂(PF₃)₂(PPh₃)₂], cis-[RuCl₂(PF₂(NMe₂)}₂(PPh₃)₂], and cis-[RuCl₂(CO)(PF,)(PPh₃)₂] do not act as catalysts for the hydrogenation of oct-1 -ene, either in the presence or absence of added triethylamine. The complexes [(Ph₃P)₂(F₃P)RuCl₃RuCl(PF₃)(PPh₃)] and [(Ph₃P)₂(F₃P)-RuCl₃ RuCl(PPh₃)₂] are not active catalysts, although the latter takes up H₂ in the presence of NEt₃. The hetero-bimetallic complex [(Ph₃P)₂ClRhCl₃RuCl (PPh₃)₂] is slightly active as a hydrogenation catalyst.