Herein, the synthesis, characterization and thermal behaviour of imidazole-based two copper-phosphate mixtures, A = Cu 2 (PO 4 )(OH)ÁCu(HPO 4 )(H 2 O)Á(C 3 H 4 N 2 ) 2 . 3.25 H 2 O and B = Cu 3 (PO 4 ) 2 H 2 OÁ(C 3 H 4 N 2 ) 3 (H 2 O)Á0.1(C 3 H 4 N 2 ).3.25 H 2 O are reported. The characterization was done by adopting various electro-analyticaltechniques such as elemental analysis, X-ray Powder Diffraction (XRD), Thermogravimetric Analysis (TGA) and Derivative Thermogravimetry (DTG), Fourier Transform Infrared (FT-IR) Spectrometry, Absorption Spectrophotometry and Ultraviolet-Visible and near Infrared (UV-Vis-NIR). Differential Scanning Calorimetry performed with the heating rate 10 K/min from 297.96 to 770.46 K in normal atmosphere for both mixtures. DSC data indicated that both mixtures A and B are exhibiting exothermic property by their net specific heat capacities (C p ) −11.11 and −2.83 J/g K, respectively. Therefore, these complex mixtures can be utilized as heat dissipation materials. Both mixtures A and B undergo phase change in terms of hydrated phase to dehydrated phase up to 356 and 392 K, respectively. The specific heat capacity of Mixture A during hydration, C p = 2.54 J/g K, is higher than the tin, lead, stainless steel, glass and aluminium at their respective melting points. This mixture is also found better than the commercial product based on lithium ion battery in terms of specific heat capacity. From UV-Vis-NIR analysis, it is found that the mixtures A and B are showing semiconducting behaviour with band gaps 1.66 and 1.68 eV, respectively. The average crystallite sizes of these nano-complex mixtures are 35.29 and 30.94 nm and these were calculated using the Debye-Scherrer equation and Williamson-Hall method.

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In weakly acidic, aqueous buffer (MeCO2-+ bipy), the complex ion [Mn2IV(μ-O)2(μ-MeCO2)(bipy)2(H2O)2]3+, 1 (bipy = 2,2prime-bipyridine), coexists in rapid equilibrium with its hydrolytic derivatives, [Mn2IV(μ-O)2(bipy)2(H2O)4]4+, 2, and [Mn2IV(μ-O)2(μ-MeCO2)(bipy)(H2O)4]3+, 3. The solution quantitatively oxidizes hydrogen peroxide to oxygen and ascorbic acid to dehydroascorbic acid, itself being reduced to MnII. In the presence of excess reductant, the reactions follow simple first-order kinetics with no evidence for the accumulation of a significant amount of any intermediate manganese complex. The ascorbate anion shows overwhelming kinetic dominance over ascorbic acid, but no evidence is available for deprotonation of hydrogen peroxide. The preferred intimate mechanism for hydrogen peroxide is inner sphere but that for ascorbic acid is uncertain. For both reductants, increased extent of aquation leads to increased kinetic activity in the order: 1 < 2 < 3.Key words: kinetics, manganese, ascorbic acid, hydrogen peroxide, 2,2prime-bipyridine.

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The formation of an intermediate ruthenium(iii) thiolate complex by the interaction of thiols, RSH (R = glutathione and l-cysteine) and dichlorotetraaquaruthenium(iii), [RuIIICl2(H2O)4]+, is reported in the temperature range 25–40°C. The kinetics and mechanism of formation of the intermediate complex were studied as a function of [RuIIICl2(H2O)4]+, [RSH], pH, ionic strength and temperature. Reduction of the intermediate complex takes place slowly and results in the corresponding disulfides RSSR and [RuIICl2(H2O)4]+. The results are interpreted in terms of a mechanism involving a rate-determining inner-sphere one-electron transfer from RSH to the oxidant used in the present investigation and a comparison of rate and equilibrium constants is presented with activation parameters.

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