Novel half-sandwich Ru(II)-hydroxamate complexes: synthesis, characterization and equilibrium study in aqueous solution?

Dalton Transactions Pub Date: 2009-08-12 DOI: 10.1039/B908173A

Abstract

Novel half-sandwich Ru(II)-benzohydroxamate complexes were synthesized. [Ru(η6-p-cymene)(μ-bha)]2Cl2 (bhaH = benzohydroxamic acid) with (O,O) coordination of the ligand, was characterized by elemental analysis, spectroscopic (1H-NMR, IR) and ESI-MS methods. Replacement of the chloride of the precursor by CF3SO3? and reaction of the obtained [Ru(η6-p-cym)(acetone)3](CF3SO3)2 with bhaH affords [Ru(η6-p-cymene)(μ-bha)]2(CF3SO3)2, the crystal and molecular structure of which has been determined by X-ray crystallography. In this complex, the first reported structure of an organometallic Ru(II)-hydroxamate, the carbonyl oxygens of the bha ligands coordinate to one of the Ru units and the hydroxamate oxygens bridge the two Ru atoms. Hydrolytic behaviour of [Ru(η6-p-cym)Clx(H2O)3-x](2-x)+ (x = 0–3) present in aqueous solution and its complex forming capabilities with N-methyl-acetohydroxamic acid (meahaH) were studied by pH-potentiometric, 1H-NMR, UV-Vis and ESI-MS methods. Formation constants of the various species present in solution are reported. The data are consistent with the formation of the stable, monomeric [Ru(η6-p-cym)(meaha)]+ as the major species at physiological pH.

Graphical abstract: Novel half-sandwich Ru(II)-hydroxamate complexes: synthesis, characterization and equilibrium study in aqueous solution
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