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The kinetics of acid dissociation of cobalt(II) complexes of novel C-functionalized 13-membered macrocyclic dioxotetraamines was studied using stopped-flow spectrophotometry at different temperatures. The results indicated the dissociation rate follows the law v d ϭ. On the basis of the experiment facts obtained, the dissociation kinetics is interpreted by a mechanism involving the negatively charged carbonyl oxygen of the complex being rapidly protonated in a pre-rate-determining step, the ratedetermining step being intramolecular hydrogen (enolic tautomer) migration (to imine nitrogen). The dissociation rate reached a plateau in strongly acidic solution. K 1 and K 2 of the prerate-determining steps and k of the rate-determining step were obtained by means of non-linear least-squares fitting method, and corresponding activation parameters were also obtained by means of temperature coefficient method. The influence of the substituents to the acid dissociation rates has been discussed. The Brö nsted type linear-free energy relationship does exist in these C-functionalized dioxotetraamine cobalt(II) complexes. It is first found that the linear relationship between the ⌬H and ⌬S of the rate-determining step does exist in this and another analogous system.

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The Chemical Preparation of Mo(W)Co(Ni) and Their Influence on Hydrogen Storage Electrode.-Alloy powders of (III) and (VII) with large surface areas are prepared by solid state synthesis and then mixed with a hydrogen storage alloy. Electrochemical measurements demonstrate that the obtained mixed hydrogen storage alloy electrodes exhibit a higher activation rate, a higher discharge capacity, and better high rate discharge characteristics compared to the unmodified hydrogen storage alloy electrode. -(LIU, J.; WANG, W. H.; YE, S. H.; GAO, X. P.; YUAN, H. T.; SONG, D. Y.; ZHANG, Y. S.; J.