Pendant-bridging-chelating-cleavage: A series of bonding modes in ruthenium(II)-BINAPO complexes

Article abstract of DOI:10.1021/om050568m

Reaction of 1,1'-bis(diphenylphosphino)binaphthol (BINAPO, 1) with [RuCl₂(η⁶-arene)]₂ in methanol leads to dinuclear BINAPO-bridged Ru compounds [{RuCl₂(η⁶-p- cymene)}₂-(μ-BINAPO)], 2a, in near quantitative yield. In dichloromethane or acetonitrile, 1 preferably affords mononuclear species in which one of the phosphine centers remains uncoordinated. These complexes can be further stabilized by reaction with BH₃ to afford, for example, [RuCl₂(η⁶-p-cymene)(η¹-BINAPO-BH ₃)], 4a. Upon heating a mixture of 1 and [RuCl₂- (η⁶-p-cymene)]₂ in DMF, P-O bond cleavage occurs to afford [RuCl(η²-PPh₂-BINOL)-(η⁶-p- cymene)], 5a, bearing an anionic PO-chelating ligand. Ligand 1 acts as an intact chelate when reacted with [Ru₂(μ-Cl)₃(η ⁶-p-cymene)₂][PF₆] to yield [RuCl(η⁶-p-cymene)(η²-BINAPO)]-[PF₆], 7. Reaction of 1 with [RuCp(CH₃CN)₃] [PF₆] in acetonitrile or chloroform affords [{RuCp(CH₃CN)₂} ₂(η-BINAPO)][PF₆]₂, 8, and [RuCp(CH ₃CN)(η²-BINAPO)] [PF₆], 9, respectively. The solid-state structures of 1, 2a, 4a, and 7 are reported, that of 2a representing a rare structural example of a molecule with a bridging binaphthyl-type ligand.