Voltammetry of [Ru(Hedta)(OH2)] at HMDE

457-459Electrochemical reduction of [RuIII(Hedta)(OH2)] has been studied at HMDE in different electrolytes in the pH range 1-11.2 by employing cyclic voltammetry, chronoamperometry and chronopotentiometry. Kinetic parameters such as diffusion coefficient, transfer coefficient and heterogeneous electron transfer rate constants have been evaluated. A mechanism for the electrochemical reduction of the ruthenium centre is proposed

Facile dihydroxylation of styrene using clay based catalysts

Dihydroxylation of styrene to 1-phenyl-1,2-dihydroxyethane is studied using iodosyl benzene as an oxidant and various modified bentonite clays (1 M-H-clay; proton exchange; Fe-exchanged clay; and Mn(III)-salen-exchanged clay) as catalyst. Catalytic activity was found to be higher for Fe-exchanged clay for intermediate epoxide formation. Studies clearly show that free Fe(III) species present in the interlayer space are responsible for its reactivity. The intermediate epoxide is converted to 1-phenyl-1,2-dihydroxy-ethane by Bronsted acidity of the clay and the water present in the reaction media

Synthesis, characterization and reversible binding of dioxygen and carbon monoxide in ruthenium(III) schiff-base complexes. Effect of equatorial substitution on the O<SUB>2</SUB> and Co affinities

Synthesis of a series of ruthenium(III) Schiff-base complexes of the type K[RuLX<SUB>2</SUB>] (where L = dibasic Schiff bases derived from methoxy, chloro substituted salicyl-aldehyde with o-phenylenediamine, propylenediamine and ethylenediamine, X = chloride) have been accomplished. The complexes were characterized by physicochemical methods. The formation of Ru<SUP>IV</SUP> superoxo complexes was confirmed electrochemically and by IR spectroscopy. The reversible binding of oxygen and carbon monoxide to these complexes were carried out in DMF at 10, 25 and 40°C. The substituents on salicylaldehyde increase the value of equilibrium constants KO<SUB>2</SUB> and K<SUB>CO</SUB> for the oxygenation and carbonylation reactions. The thermodynamic parameters ΔH<SUP>0</SUP>, ΔG<SUP>0</SUP> and ΔS<SUP>0</SUP> for oxygenation and carbonylation were evaluated

Oxygenation and carbonylation studies of some ruthenium(III) Schiff base complexes containing nitrogen and oxygen as donor atoms. II

Synthesis and characterization of a series of ruthenium(III) Schiff base complexes of the type [Ru<SUP>III</SUP>LXY] where L=Schiff base viz. bis(naphthaldehyde)-o-phenylenediimine (naphoph), bis(naphthaldehyde)ethylenediimine (naphen), bis(naphthaldehyde)propylenediimine (naphprop) and bis(naphthaldehyde)diethylenetriimine (naphdien); X=Cl and Y=Cl imidazole (Im) or 2-methylimidazole (2-MeIm) are reported. Elemental analysis, conductivity and IR studies of the complexes suggest an octahedral geometry around ruthenium. Magnetic moments of the complexes indicate a single unpaired electron in a low spin d<SUP>5</SUP> configuration. Oxygenation studies in DMF or THF solutions suggest the reversible binding of molecular oxygen to the ruthenium(III) complexes. EPR studies at liquid nitrogen temperature and UV---Vis measurements at room temperature support the formation of a Ru(IV) superoxo species [Ru<SUP>IV</SUP>L(O<SUB>2</SUB>)<SUP>−</SUP>Y]. The EPR spectrum of the Ru(IV) superoxo complex at 77 K (g<SUB>1</SUB>=2.063, g<SUB>2</SUB>=2.047, g<SUB>3</SUB>=2.023) is consistent with the odd electron occupying a highly localized antibonding π<SUP>∗</SUP> orbital of molecular oxygen. The reversible binding of O<SUB>2</SUB> and CO has been carried out in DMF at 10, 25 and 40°C. The complexes show discrimination against the binding of CO over O<SUB>2</SUB> as evinced by values of K<SUB>O<SUB>2</SUB></SUB> and K<SUB>CO</SUB> in the complexes. The thermodynamic paramegers ΔH°, ΔG° and ΔS° for oxygenation and carbonylation reactions are evaluated

Synthesis, characterisation, oxygenation and carbonylation of ruthenium(III) schiff base complexes

Some ruthenium(III) Schiff base complexes of the type [RuLXY]<SUP>n</SUP> where L=Schiff base namely, bis(α-hydroxyacetophenone)-o-phenylenediimine (α-acetop.oph), bis(2-hydroxy-4-methoxyacetophenone) -o-phenylenediimine (4-MeOacetop.oph), bis(α-hydroxyacetophenone)ethylenediimine (α-acetop.en), bis(2-hydroxy-4-methoxyacetophenone)ethylenediimine (4-MeOacetop.en), bis(α-hydroxyacetophenone) propylenediimine (α-acetop.prop), bis(2-hydroxy- 4-methoxyacetophenone)propylendiimine (4-MeOacetop.prop), bis(a-hydroxyacetophenone)diethylenetriimine (α-acetop.dien), bis(2-hydroxy-4-methoxyacetophenone) diethylenetriimine (4-MeOacetop.dien), n=−1 when X=Y=Cl<SUP>−</SUP>, n=0 when X=imidazole (Im), 2-methylimidazole (2-MeIm) and Y=Cl<SUP>−</SUP> were synthesised and characterised by physicochemical methods. The reversible binding of molecular oxygen as well as carbon monoxide was carried out in DMF. The complexes show discrimination against the binding of CO over molecular oxygen as evinced by the values of K<SUB>O<SUB>2</SUB></SUB> and K<SUB>CO</SUB> in the complexes. The thermodynamic parameters ΔH°, ΔG°, ΔS° for the carbonylation and oxygenation reactions at 10, 25 and 40°C are evaluated

Kinetics and mechanism of the ligand substitution reaction of aquodiethylenetriaminepentaacetatoruthenate (III) in aqueous solution

The kinetics of ligand substitution reactions of [Ru(H2dtpa) (H2O)] (2̲) (H2dtpa=diprotonated diethylenetriaminepentaacetic acid) were studied as a function of ligand (L') concentration, pH (2.5-8.0) and temperature (30-45°C) at 0.2 M ionic strength. The equilibrium constants for the formation of mixed ligand complex [RuIII(dtpa) (L)] (L=2-mercaptopyrimidine, cysteine) and the distribution of various species in solution in the pH range of 2.5-8.0 were computed from potentiometric results