Synthesis and X-ray crystal structures of the cyclic oxacarbene complexes [Ru{CCH2(CH2)nCH2O}(Ph2PCH2CH2PPh2)(η-C5H5)][PF6](n = 1 or 2): Boat conformation of the 2-oxacyclohexylidene ligand

Article abstract of DOI:10.1016/S0022-328X(96)06585-0

The cyclic oxacarbene complexes [Ru{CCH₂(CH₂)_nCH₂O}(dppe)(η-C₅H₅)][PF₆] (dppe = Ph₂PCH₂CH₂PPh₂; n = 1, 1 or 2, 2) have been synthesised by reaction of hydroxyalk-1-ynes, HC≡C(CH₂)_nCH₂OH with [RuCl(dppe)(η-C₅H₅)]/NH₄[PF₆] in refluxing methanol. The X-ray crystal structures of 1 and 2 reveal essentially vertically orientated carbene ligands with the oxygen directed 'down' away from the cyclopentadienyl ring. Both carbene rings exhibit folded conformations; the five-membered ring of 1 adopts an envelope configuration whilst the six-membered ring of 2 has a boat conformation.