Arvind B. Boricha

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

Abstract Synthesis and characterization of a series of ruthenium(III) Schiff base complexes of the type [RuIIILXY] 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 d5 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 [RuIVL(O2·.)−Y]. The EPR spectrum of the Ru(IV) superoxo complex at 77 K (g1 = 2.063, g2 = 2.047, g3 = 2.023) is consistent with the odd electron occupying a highly localized antibonding π* orbital of molecular oxygen. The reversible binding of O2 and CO has been carried out in DMF at 10, 25 and 40 °C. The complexes show discrimination against the binding of CO over O2 as evinced by values of KO2 and KCO 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

Abstract Some ruthenium(III) Schiff base complexes of the type [RuLXY] n 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(α-hydroxyacetophenone)diethylenetriimine (α-acetop.dien), bis(2-hydroxy-4-methoxyacetophenone) diethylenetriimine (4-MeOacetop.dien), n = −1 when X=Y=Cl − , n =0 when X=imidazole (Im), 2-methylimidazole (2-MeIm) and Y = Cl − 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 O 2 and K CO in the complexes. The thermodynamic parameters ΔH°, ΔG°, ΔS° for the carbonylation and oxygenation reactions at 10, 25 and 40°C are evaluated.

Synthesis, characterization and reversible binding of dioxygen and carbon monoxide in ruthenium(III) schiff-base complexes. Effect of equatorial substitution on the O2 and Co affinities

Abstract Synthesis of a series of ruthenium(III) Schiff-base complexes of the type K[RuLX2] (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 RuIV 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 KO2 and KCO for the oxygenation and carbonylation reactions. The thermodynamic parameters ΔH0, ΔG0 and ΔS0 for oxygenation and carbonylation were evaluated.

Recovery of value-added products from cathode and anode material of spent lithium-ion batteries

Herein we report a low cost and eco-friendly approach for the recovery of metals from cathode and anode materials of mobile phone spent lithium-ion batteries (LIBs). Li-based metal oxide and graphite were efficiently separated from their respective foils and used for lixiviation. Acetic acid (CH3COOH) and water were used as lixiviants for the recovery of metals from cathode and anode materials respectively. It was found that with 3 M Acetic acid and 7.5 vol% H2O2 as reducing agent 99.9% Li, 98.7% Co, and 99.5% Mn were leached out from cathode material in 40 min at 70 °C and a pulp density of 20 g/L. Besides the cathode leaching, Li was also extracted from anodic material graphite using water as a solvent and further recovered as solid Li2CO3 (99.7% Li). The kinetic evaluation of the cathode lixiviate process was studied using three different shrinking-core kinetic Models and established that the reaction follows the product layer diffusion controlled mechanism. From the cathode leach liquor, 99% Co was recovered as metal sulfide by controlled sulfide precipitation with 99.2% purity, and subsequently, MnCO3 and Li2CO3 were obtained with the purity of 98.7% and 99.4%, respectively. The purity of the salts revealed that these products recovered from spent LIBs might be utilized in the electrochemical energy-storage applications. In addition, this recycling process would promote the sustainable development of the battery industry.

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

The kinetics of ligand substitution reactions of [Ru(H2dtpa) (H2O)] (2) (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.AbstractКинетику реакций лигандного замещения [Ru(H2dtpa) (H2O)] (где H2dtpa=дипротонированная диэтилтриаминпентауксусная кислота) исследовали в зависимости от концентрации лиганда, pH (2,5–8,0) и температуры (30–45°C) при ионной силе 0,2 M. На основе потенциометрических измерений рассчитаны на ЭВМ константы равновесия образования комплексов смешанных лигандов [RuIII(dtpa) (L)] (где L=2-меркаптопиримидин, цистеин) и распределение различных частиц в растворе при pH=2,5–8,0.