Diene and dienyl complexes of transition elements : II. The protonation of η-diaryldienone(η-cyclopentadienyl)-rhodium(I) and -iridium(I) complexes

Abstract

Reaction of [M(η 4-PhCHCRCHCHCOPh)(η 5-C 5H 5)], [M = Rh or Ir; R = H or Me] with HBF 4 or HPF 6 affords the crystalline salts [M(η 3-PhCHCRCHCH 2-COPh)(η 5-C 5H 5)]Y, [Y = BF 4 or PF 6], in which the acyl CO group is coordinated to the metal. HCl and HBr also protonate the dienone complexes (M = Rh) at carbon, giving the covalent derivatives [RhX(η 3-PhCHCHCHCH 2COPh)(η 5-C 5H 5)], [X = Cl, Br]. A mechanism involving endo addition of H + to the η 4-dienone ligand is in accord with deuteration studies. 1H and 13C NMR spectra of the new complexes are discussed. The reactions of [Rh(η 4-PhCHCHCHCHPh)-(η 5-C 5H 5)] with HCl and HBr are also reported.