• B S Prabhananda

      Articles written in Journal of Chemical Sciences

    • ESR study of mixed ligand complexes of copper with dialkyl-diselenophosphate as one of the ligands

      G Krishnamoorthy B S Prabhananda P M Solozhenkin

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      A large number of mixed ligand complexes of copper with di-i-propyldiselenophosphate as one of the ligands have been prepared by ligand exchange reactions and have been identified using electron spin resonance. From the measured ESR parameters in chloroform solutions it was concluded that (i) the measuredgo (and notACu) could be used to identify the mixed ligand complexes (in addition to ligand hyperfine splittings) (ii) the changes in spin transfer to77Se and31P on the same ligand dSeP are uncorrelated suggesting that the dominant mechanism of spin transfer to near neighbours77Se is different from that to the next neighbour31P. (iii) Observations on31P splittings show that on formation of mixed ligand complex, the spin density on one ligand increases at the expense of other.

    • Use of aqueous DMSO in resolving ‘proton ambiguity’ in the formation of monocomplexes of iron(III)

      G Krishnamoorthy B S Prabhananda

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      The formation of FeL2+ (L=N3, SCN) in H2O-dimethylsulphoxide (DMSO) mixtures was studied by equilibrium, stopped flow and temperature jump observations. The acid dissociation constants associated with LH and Fe(H2O)63+ and the formation constants associated with FeL2+ were determined at various solvent compositions. In kinetic studies, the solvent composition dependence of the overall equilibration rate was explained in terms of equations predicted by a reaction scheme which includes DMSO coordinated species. Analysis of results on the basis of these equations identified Fe·OH2+·HN3 and Fe3+·SCN as the dominant transition states contributing to pH-independent paths of formation of FeL2+ in the cases of N3 and SCN respectively. Thus, the results which support the Eigen-Tamm-Wilkins mechanism have resolved the mechanistic ambiguity in the pH-independent paths of formation of FeL2+. It is also shown that we cannot neglect species such as FeOH·HN32+, Fe·OH·N3+ and Fe·HN33+ while accounting for the kinetic behaviour.

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