Synthesis and spectral studies of the biologically active complexes of tantalum(V) with N-alkylphenothiazines

Dioxo-bridged binuclear tantalum(V) complexes with six N-alkylphenothiazines (NAP) of general formula [TaO(L)(C2O4)]2C2O4, (L=NAP) have been prepared and characterized on the basis of elemental analysis, conductometric, magnetic and thermogravimetric data. The spectra of the complexes indicate that both the phenothiazine ligands and oxalate groups are coordinated to tantalum in a bidentate fashion, suggesting a coordination number of six around metal. The fungitoxicity of the isolated complexes against several fungi has been investigated.     

Ruthenium(III)-catalyzed oxidation of amides by sodium N-bromobenzenesulphonamide in hydrochloric acid: a kinetic and mechanistic study

The kinetics of the RuIII-catalyzed oxidation of urea and substituted ureas namely: methylurea, ethylurea and propylurea, to the corresponding hydrazines by sodium N- bromobenzenesulphonamide or bromamine-B (BAB) in HCl medium has been studied at 303K. The reaction rate shows a first order dependence each upon [BAB], [amide] and [RuIII] and is dependent on [H+]. Addition of halide ions and benzenesulphonamide do not significantly affect the rate. Proton inventory studies were made in H2O-D2O mixtures for urea and methylurea. A Taft linear free energy relationship is observed for the reaction with *=–2.95 and =–0.25, showing that electron-donating groups enhance the rate. An isokinetic relation is observed with =370K, indicating that enthalpy factors control the rate; this result is also confirmed by Exner Criterion which showed a linear plot for the logarithms of rate constants at the highest and lowest temperatures employed. The protonation constant of monobromamine-B has been evaluated and equals 7.5. A mechanism consistent with the observed kinetic data has been proposed.