Ratan Kumar Banerjee

Abstract: Mixed chelate complexes of identical composition of the type (NH4)2[UO2(L)2B] and (NH4)2[UO2(L)2X2] where L = anion of cupferron, B  CO″3, C2O″4 and X  F′, Cl′ have been prepared from different starting materials Both the fluoro- and chloro-complexes (NH4)2[UO2(L)2X2] have been isolated in two different forms (one orange-yellow and one yellow) by different methods Yellow forms of (NH4)2[UO2(L)2X2] undergo conversion to the corresponding orange-yellow forms under suitable conditions All these complexes have been thoroughly characterised through elemental analysis, conductance data, X-ray, IR, electronic, NMR spectra as well as thermogravimetric and differential thermal analyses Possibility of the complex (NH4)2[UO2(L)2X2] to exist in two geometrical isomeric forms has been indicated The orange red complex cis-[UO2(L)2(H2O)2] on being refluxed with acetone, changed to a yellow complex, almost insoluble in most of the common organic solvents Various physico-chemical studies indicate it to be a hydroxybridged dinuclear complex H[(UO2)2(L)4OH(H2O)2] The ν3-values (cm−1) of UO22+-entity from IR-spectra have been used to calculate the force constant, FUO in mdynes/A and the bond length RUO in A of the UO bond Using ν3of the UO22+-entity as a molecular probe, the inorganic ligands and acid residues like F′, Cl′, CO″3 and CO″4 have been arranged in a series, which is similar to the mutual displacement series of one ligand by another in the uranyl compounds

Abstract: New series of uranyl complexes derived from 7-formyl-8-hydroxy quinoline with hydrazine hydrate (HL1), methyl hydrazine (HL2), 1,2-diaminoethane (HL3), 1,2-diaminobenzene (HL4) and 2-aminopyridine (HL5) have been prepared and characterized by elemental analyses, (1H NMR and 13C NMR, electronic and vibrational spectra) and different physical techniques. The magnetic and spectral data suggest a distorted octahedral structure for all complexes. The labile EtOH molecule in compounds (5), (7) and (9) is equatorially bonded to the uranium ion and its hydrogen is bonded to the axial oxygen of the uranyl moiety. The ligands contain intramolecular hydrogen bonds. The FU-O(mydn/Ao) and the bond length RU-O(Ao) of the bond were calculated from the IR data. In the present work it has been proposed a novel relationship between symmetric “V1” and asymmetric “v3” O-U-O frequencies independent on the masses of oxygen (Mo) and uranium (Mu) atoms.

Abstract: A series of dioxouranium(VI) complexes with 7-carboxaldehyde-8hydroxyquinoline (oxine) and with some of its Schiff bases, LH, have been prepared and characterized by elemental analyses, electronic and vibrational spectral studies. All complexes except those of the oxine have the [UO2L2] · EtOH, stoichiometry (n=0, 1, 2 or 4). The uranyl complexes of the oxine have the formula [UO2L2(LH)]. The i.r. spectra reveal all ligands to be monobasic bidentate chelating agents coordinated to the uranium(VI)via the enolized phenolic OH and aldehydic oxygen or azomethine nitrogen atom. The force constant fU-o (mdyn A) and the bond length rU-o (A) of the U-O bond are also calculated and related to the electronic properties of thep-substituents.

Abstract: A series of complexes formed, by the interaction of UO2 (AcO)2. 2H2 O and some potentially bidentate ligands, aniline, o-hydroxy, o-carboxy, o-chloro, o-methoxy and o-methylaniline-7- carboxaldehyde-8- hydroxyqvinoline abbreviated as ML1., H2L2, H2L3, HL4, HL5 and HL6, respectively, viated as HL1 H2L2, H2L3., HL4., HL5., and HL6, respectively have been synthesized. The products wre characterized by elemental analyses, magnetic moments and spectral measurements. All the ligands behave as monobasic bidentate chelating agents coordinating to the uranium(VI) ion via the deprotonated phenolic OH and aldehydic oxygen and/or azomethine nitrogen. Thermal stabilities of the ligands and complexes have been s tudied using thennogravimetric analysis (TGA).

Abstract: Complexes of CoII, NiII, CuII, ZnII, CdII, HgII and UO 2 II with benzil bis(4-phenylthiosemicarbazone), H2BPT, have been synthesized and their structures assigned based on elemental analysis, molar conductivity, magnetic susceptibility and spectroscopic measurements. The i.r. spectra suggest that the ligand behaves as a binegative quadridentate (NSSN) (CoII, CuII, HgII and UO 2 II complexes) or as a binegative quadridentate-neutral bidentate chelating agent (NiII, ZnII and CdII complexes). Octahedral structures for the CoII and NiII complexes and square-planar structure for the CuII complex are suggested on the basis of magnetic and spectral evidence. The crystal field parameters (Dq, B andμ B) for the CoII complex are calculated and agree fairly well with the values reported for known octahedral complexes. The ligand can be used for the microdetermination of NiII ions of concentration in the 0.4–6×10−4 mol l−1 range and the apparent formation constant for the species generated in solution has also been calculated.

Abstract: Mixed ligand complexes of dioxouranium (VI) of the type [UO(2)(Q)(L)·2H(2)O] have been synthesized using 8-hydroxyquinoline (HQ) as a primary ligand and amino acids (HL) such as L-threonine, L-tryptophan, and L-isoleucine as secondary ligands. The metal complexes have been characterized by elemental analysis, electrical conductance, magnetic susceptibility measurements, and spectral and thermal studies. The electrical conductance studies of the complexes indicate their nonelectrolytic nature. Magnetic susceptibility measurements revealed diamagnetic nature of the complexes. Electronic absorption spectra of the complexes show intraligand and charge transfer transitions, respectively. Bonding of the metal ion through N- and O-donor atoms of the ligands is revealed by IR studies, and the chemical environment of the protons is confirmed by NMR studies. The thermal analysis data of the complexes indicate the presence of coordinated water molecules. The agar cup and tube dilution methods have been used to study the antibacterial activity of the complexes against the pathogenic bacteria S. aureus, C. diphtheriae, S. typhi, and E. coli.