The reactions between Fe(Phen) 2þ 3 [phen=tris-(1,10) phenanthroline] and Co(CN) 5 X 3) (X=Cl, Br or I) have been studied in aqueous acidic solutions at 25°C and ionic strength in the range I=0.001-0.02 mol dm )3 (NaCl/HCl). Plots of k 2 versus p I, applying Debye-Huckel Theory, gave the values )1.79±0.18, )1.65±0.18 and 1.81±0.10 as the product of charges ðZ A Z B Þ for the reactions of Fe(Phen) 2þ 3 with the chloro-, bromo-and iodo-complexes respectively. Z A Z B of % À2 suggests that the charge on these Co III complexes cannot be )3 but is )1. This suggests the possibility of protonation of these Co III complexes. Protonation was investigated over the range [H + ]=0.0001 )0.06 mol dm )3 and the protonation constants K a obtained are 1.22 · 10 3 , 7.31 · 10 3 and 9.90 · 10 2 dm 6 mol )3 for X=Cl, Br and I, respectively.

The effect of triton X-100 micelles on the aquation of Fe(Me,phen):+ has been investigated with triton X-100 as solvent. In liquid triton X-100, over a range of [H,O], (0.2-2.0 mol dm-7, significant rate enhancement factors of 35-140 are observed. Acid inhibits the rate of aquation at fixed [H,O],. A mechanism based on effective solvent participation in a chemical environment similar to that in reversed micelles is proposed in liquid triton X-100 with dispersed water pockets. This mechanism predicts direct H,O substitutions into the coordination sphere of Fe(Me,Phen):+ in the highly polar water pockets or -cavities where the Fe'I complex molecules are solubilized. Changes in the tumbling rate, mobility, structure, nucleophilicity and activity of water are suggested to account for the observed changes in the rate of aquation as a function of [H,O],, in the peculiar chemical environment of the water pockets. All k,-[H,O], profiles are structured and exhibit maxima with k (max) shifted to progressively higher [H,O], as the fixed concentration of [H+], is increased.

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Mixed-micelle formation in the binary mixtures of dodecyltrimethylammonium bromide (DTABr) and cetyltrimethylammonium bromide (CTABr) surfactants in water-ethanolamine mixed solvent systems has been studied by conductometric method in the temperature range of 298.1 to 313.1 K at 5 K intervals. It was observed that the presence of ethanolamine forced the formation of mixed micelle to lower total surfactant concentration than in water only. The synergistic interaction was quantitatively investigated using the theoretical models of Clint and Rubingh. The interaction parameter β12 was negative at all the mole fractions of DTABr in the surfactant mixtures indicating a strong synergistic interaction, with the presence of ethanolamine in the solvent system resulting in a more enhanced synergism in micelle formation than in water only. The free energy of micellization ΔGM values was more negative in water-ethanolamine mixed solvent system than in pure water indicating more spontaneity in mixed micelle formation in the presence of ethanolamine than in pure water.