π-Arene and π-phenoxo complexes of ruthenium and rhodium
Abstract
The action of fluoroboric acid on dihydridotetrakis(triphenylphosphine)ruthenium(II) or on acetatohydridotris(tri-phenylphosphine) ruthenium(II) in methanol produces the salt [RuH(η6-C6H5PPh2)(PPh2)3][BF4] in which the phenyl group of one triphenylphosphine molecule is π-bonded to the metal. In the presence of benzene or toluene, similar arene complexes, [RuH(η6-Ar)(PPh3)2][BF4] are obtained.
The interaction of RuH2(PPh3)4 with phenol gives a neutral complex, RuH(C6H5O)(PPh3)2, that may also be obtained with two additional molecules of phenol hydrogen bonded to the oxygen atom of the phenoxo-ligand. The C6H5O– ligand can be considered to be bound as an η6-phenoxo or probably more realistically as an η5oxacyclohexadienyl ligand. Re-investigation of the compounds obtained by action of phenol on methyl- or phenyl-tris(triphenyIphosphine)rhodium(I) shows that these also are α-phenoxo-complexes.
An η6-toluene-p-sulphonate is also described.
I. r., 1H, and 31P n.m.r. spectra of the compounds are given.