Ruthenium complexes containing pyridine-2,6-dicarboxylato ligands

Characterization of a Mixed-Valence Ru(II)/Ru(III) Ion-Pair Complex. Unexpected High-Frequency Electron Paramagnetic Resonance Evidence for Ru(III)-Ru(III) Dimer Coupling

In this contribution, we report the synthesis and full characterization of the first mixed-valence Ru(II)/Ru(III) ion-pair complex, [Ru^II(bipy)₂(pic)]⁺[cis-Ru^IIICl₂(pic)₂]^-, in the solid state and in aqueous solution, where bipy = 2,2'-bipyridine and pic^- = picolinate. In addition, unexpected high-frequency electron paramagnetic resonance evidence for interactions between two neighboring Ru(III) ions, resulting in a triplet state, S = 1, was found.

Catalytic Oxidation of Water to Dioxygen by Mononuclear Ru Complexes Bearing a 2,6-Pyridinedicarboxylato Ligand

The synthesis, purification, and isolation of mononuclear Ru complexes containing the tridentate dianionic meridional ligand pyridyl-2,6-dicarboxylato (pdc^2- ) of general formula [Ru^III (pdc-κ³ -N¹ O² )(bpy)Cl] (1^III ) and [Ru^II (pdc-κ² -N¹ O¹ )(bpy)₂ ] (2^II ) (bpy is 2,2'-bipyridine) is reported. These two complexes and their derivatives were thoroughly characterized through spectroscopic (UV/Vis, NMR) and electrochemical (cyclic voltammetry, differential pulse voltammetry, and coulometry) analyses, and three of the complexes were analyzed by single-crystal X-ray diffraction techniques. Under a high anodic applied potential, both complexes evolve towards the formation of Ru-aquo/oxo derivative species, namely, [Ru^III (pdc-κ³ -N¹ O² )(bpy)(OH₂ )]⁺ (1-O) and [Ru^IV (O)(pdc-κ² -N¹ O¹ )(bpy)₂ ] (2-O). These two complexes are active catalysts for the oxidation of water to dioxygen and their catalytic activity was analyzed through electrochemical techniques. A maximum turnover frequency (TOF_max )=2.4-3.4×10³  s^-1 was calculated for 2-O.

Syntheses and crystal structures of ruthenium complexes with bidentate salicylaldiminato and dithiophosphato ligands

Treatment of the bidentate Schiff base 2-[(2,6-diisopropyl-phenylimino)-methyl]-phenol (HL1) with one equivalent of (Et4N)[RuCl4(MeCN)2] in the presence of triethylamine afforded (Et4N)[RuCl3(κ 2-N,O-L1)(MeCN)] (1), which reacted with two equivalents of K[S2P(O i Pr)2] to produce a neutral ruthenium(III) complex [Ru(κ 2-N,O-L1){η 2-S2P(O i Pr)2}2] (2) bearing both salicylaldiminato and dithiophosphato ligands. Reactions of the bidentate Schiff bases 2-[(3-chloro-phenylimino)-methyl]-phenol (HL2) and 2-[(2,4,6-trimethyl-phenylimino)-methyl]-phenol (HL3) with one equivalent of [Ru(CO)2Cl2] in the presence of triethylamine led to formation of the corresponding anionic ruthenium(II) carbonyl complexes (Et3NH)[RuCl2(κ 2-N,O-L2)(CO)2] (3) and (Et3NH)[RuCl2(κ 2-N,O-L3)(CO)2] (4). The molecular structures of complexes 2–4 have been determined by single-crystal X-ray diffraction.

Luminescence of uranyl ion complexed with 2,6-pyridine dicarboxylic acid as ligand in acetonitrile medium: observation of co-luminescence

Luminescence from UO2 2+ (uranyl ion) complexed with 2,6-pyridine dicarboxylic acid (PDA) has been studied using acetonitrile (MeCN) as solvent between pH 1.0 and 6.0. The enhancement in luminescence intensity because of sensitization by PDA in the non-aqueous environment provided by the MeCN is found to be one order better than in aqueous medium. The luminescence is further enhanced by about four times following the addition of Y3+; a process known as co-luminescence. This is the first study on co-luminescence of uranyl ion in its PDA complex. Lifetime studies indicate the presence of two species having different micro-environments. Formations of both intra and inter molecular complexes are believed to be responsible for enhancement due to co-luminescence.

Synthesis of an oligomer ruthenium complex and its catalysis in the oxidation of alcohols

The catalyst showed high efficiency in the oxidation of alcohols to ketones or acids and can be recycled several times.