Unique complexation by the tridentate ligands, 6-diphenylphosphino-2-pyridonate (pyphos) and 6-diphenylphosphino-2-pyridone (pyphosH), on ruthenium (II): Crystal structures of (pyphosH)RuCl(μ-Cl)Mo2Cl(pyphos)3, RuCl2(CO) (pyphosH)2, [Ru(pyphos)3](μ-Na)2[Ru(pyphos)3]

Article abstract of DOI:10.1016/s0020-1693(97)06003-9

The diphenylphosphino-2-pyridone ligand (pyphosH) and its anion ligand, pyridonate (pyphos), coordinated to the ruthenium(II) center through two modes: bidentate P-N chelation and monodentate P coordination. Reaction of Mo₂(pyphos)₄ (2) with [RuCl₂(η⁶-p-cymene)]₂ (3) afforded an unexpected trinuclear complex (pyphosH)RuCl(μ-Cl)Mo₂Cl(pyphos)₃ (5) accompanied by a monomeric complex (η⁶-p-cymene)RuCl₂(pyphosH) (4). In complex 5, three pyphos ligands coordinated to a quadruply-bonded Mo₂ core in three different modes: O-N chelation with free phosphine moiety, O-N chelation with a phosphorus atom bound to a ruthenium atom, P-N chelation with an oxygen atom bridged to the ruthenium atom; thereby the pseudo octahedral ruthenium center was surrounded by a phosphorus atom and a nitrogen atom of a pyphosH ligand (P-N chelation), two trans-arranged chloro atoms, the oxygen atom and the phosphorus atom of the two pyphos ligands. Reaction of RuCl_x(CO)_y with pyphosH gave a mononuclear complex RuCl₂(CO) (pyphosH)₂ (6), which has two pyphosH ligands bound to the ruthenium atom through P-N chelation and monodentate P coordination and involves two hydrogen bondings, NH?Cl and OH?Cl. In addition, treatment of Ru₂(OAc)₄ (7) with the sodium salt of the pyphos ligand afforded a heterotetrametallic complex [Ru(pyphos)₃](μ-Na)₂[Ru(pyphos)₃] (8) in which each pseudo octahedral ruthenium(II) center has three pyphos ligands through P-N chelation and two sodium ions were coordinated by four oxygen atoms in distorted tetrahedral geometry.