No abstract

No abstract

¼ N-[(1)-pyridin-2-ylmethylidene]benzohydrazide, Phen ¼ 1,10-phenanthroline, bipy ¼ 2, 2 0 -bipyridine, Dien ¼ diethylenetriamine, ImH ¼ imidazole), have been synthesized and characterized using various physico-chemical techniques. L 1 is coordinated to copper(II) neutral and uninegatively charged tridentate chelating agent via the azomethine nitrogen, pyridine nitrogen, and carbonyl oxygen. The copper(II) complexes are paramagnetic with octahedral stereochemistry. The crystal structures of the complexes reveal the presence of structure consisting of a tridentate N, N, O donor Schiff base, tridentate NNN donor polyamine or N, N donor heterocyclic base and the copper(II) center. In 1, 2, and 4, water is present as a coordinating molecule whereas in 2 and 4 it is also present as lattice water. In discrete monomeric species all complexes show significant hydrogen-bonding interactions. H-bridges are also present in the solid state structure. Complexes 1-4 effectively catalyze the dismutation of superoxide (O À 2 ) in alkaline nitro blue tetrazolium assay and IC 50 values were determined. The susceptibility of certain strains of bacteria toward the precursors L 1 and their complexes were also evaluated.

The kinetics and equilibria involved in the formation of monoacetatoiron(III) from iron(II1) in aqueous solution has been investigated at ionic strength 0.50 M and temperatures ranging from 5.2 to 25 "C for kinetic studies and 5.2 to 41 "C for equilibria. The results support the view that the mechanism of the acid independent reaction involves the reactants FeOH2+ and CH3COOH in an interchange dissociative (I,) mechanism with AH * = 11.1 f 2.2 kcal mole '. The nature of the acid dependent reactions remains unresolved.Les cinttiques et les tquilibres impliquis dans la formation du monoacttate de fer(II1) a partir du fer(II1) en solution aqueuse, ont t t t ttudits a force ionique de 0.50 M e t sur une tchelle de temptrature allant de 5.2 a 25 "C pour les ttudes cinttiques et de 5.2 a 41 "C pour les tquilibres. Les rtsultats montrent que le mtcanisme de la rtaction, indtpendant en acide, implique les rtactifs FeOH2+ et CH,COOH dans un mecanisme d'tchange et de dissociation (I,) avec A H * = 11.1 2.2 kcal mol-I. La nature des rtactions qui dependent de l'acide demeure non tlucidte.

Niobium(V) and Tantalum(V) Complexes [MLX 4 ] (where M = Nb/Ta; X = Cl/NCS; L = 2-aminothiophenol or 2-aminophenol) have been synthesised and characterised on the basis of elemental analysis, conductivity measurements, Ir, UV-vis and 'H NMR studies. The ligands behaves as mononegative bidentate donor. The value of magnetic moment of 0.35 -0.43 BM is a consequence of combined effects of spin-orbit coupling and distortions of the ligand field from a full octahedral symmetry.