Framework Conversion of Oxido-Bridged Dinuclear Ruthenium Complexes

Syntheses, properties, and reactions of hydroxido- or oxido-bridged dinuclear ruthenium complexes bearing a tridentate auxiliary ligand, ethylbis­(2-pyridylmethyl)­amine (ebpma) or benzylbis­(2-pyridylmethyl)­amine (bbpma), have been investigated. Reduction reactions of a singly oxido-bridged diruthenium complex bearing ebpma, [{RuIII,IVCl2(ebpma)}2(μ-O)]+ ([2 Cl ]+), by zinc in acetonitrile afforded an acetonitrile-substituted singly oxido-bridged complex in the RuIII–RuIII isovalent state, [{RuIII,IIICl­(NCCH3)­(ebpma)}2(μ-O)]2+ ([2 CH3CN ]2+). Chlorido ligand abstraction reactions using silver salts have also been attempted. Through a reaction of [2 Cl ]+ with two equimolar amounts of AgNO3 in water–acetone, a singly oxido-bridged complex having an aqua and a hydroxido, [{RuIIICl­(OH2)­(ebpma)}­(μ-O)­{RuIVCl­(OH)­(ebpma)}]2+ ([2 H2O‑OH ]2+), was obtained. Reactions with four equimolar amounts of AgL (L = CH3COO– or NO3 –) in water–acetone gave doubly oxido- and bidentate oxygen donor ligand-bridged diruthenium complexes of Ru­(III)–Ru­(IV), [{RuIII,IV(ebpma)}2(μ-O)2(μ-L)]2+ ([3 L ]2+; L = O2CCH3; [3 CH3COO ]2+, L = O2NO; [3 NO3 ]2+). Reactions of [3 L ]2+ under acidic conditions afforded a corresponding one-protonated species having the {Ru2(μ-O)­(μ-OH)} core. Reactivity and electronic structure of the oxido-bridged diruthenium complexes were studied by electrochemical, spectroscopic, and theoretical methods.