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Zinc complexes of three new amide-appended ligands were prepared and isolated and the effect of replacement of the unsubstituted pyridyl groups in these complexes with various donors was studied. The results suggest that increased steric hindrance in the equatorial plane of the zinc cation slows or prevents the amide methanolysis reaction and the slower rate of amide methanolysis is due to a side reaction involving the formation of free ligand.

Macrocyclic superoxo and hydroperoxo rhodium complexes are analyzed for its kinetic and equilibrium measurements to determine its reduction potentials, bond-dissociation energies and acidity constants.

The research presents a comparative study of the various kinetic and thermodynamic parameters with those of the corresponding amide methanolysis reaction to explain the amide hydrolysis reactivity of a [N.sub.4]O-ligated zinc complex. The various data-sets obtained from the experiments show that the amide hydrolysis reaction exhibits a saturation kinetic behavior, which is highly consistent with a mechanism involving equilibrium formation of a reactive species undergoing hydrolysis.

Treatment of the mononuclear amide-appended zinc complex [(ppbpa)Zn](ClO4)2 (1(ClO4)2) with Me4NOH·5H2O in CD3CN/D2O (3:1) results in the formation of the deprotonated amide species [(ppbpa-)Zn]ClO4 (2). Upon heating in CD3CN/D2O, this complex undergoes amide hydrolysis to produce a zinc carboxylate product, [(ambpa)Zn(O2C(CH3)3)]ClO4 (3). X-ray crystallography, ¹H and 13C NMR, IR, and elemental analysis were used to characterize 3. The hydrolysis reaction of 1 (ClO4)2 exhibits saturation kinetic behavior with respect to the concentration of D2O. Variable- temperature kinetic studies of the amide hydrolysis reaction yielded ΔH‡ = 18.0(5) kcal/mol and ΔS‡ = -22(2) eu. These activation parameters are compared to those of the corresponding amide methanolysis reaction of 1 (ClO4)2. [ABSTRACT FROM AUTHOR]