Tetramethylthiophen complexes of rhodium, iridium, palladium, and ruthenium

Abstract

New tetramethylthiophen (tmt) complexes, [M(η⁵-C₅Me₅)(tmt)][PF₆]₂(M = Rh or Ir), [Rh(diene)(tmt)][PF₆](diene = cycle-octa-1,5-diene or norbornadiene), [Ru(p-cymene)(tmt)][PF₆]₂, [Pd(η³-2-MeC₃H₄)(tmt)₂][PF₄], and [Pd(tmt)Cl₂] have been prepared: the Rh, Ir, and Ru complexes all contain η⁵-bonded tmt but the two Pd complexes (which were only partially characterised) contain S- and, possibly, η⁴-bonded tmt respectively. The 2,5-dimethylthiophen (dmt) complexes, [Ir(η⁵-C₅Me₅)(dmt)][PF₆]₂ and [Rh(cod)(dmt)][PF₆] were also prepared. The activity of these compounds as hydrogenation catalysts is discussed.