Bhagwan S. Garg

Analytical applications of thiosemicarbazones and semicarbazones: A review.

The analytical applications of thiosemicarbazones and semicarbazones are reviewed.

Oximes as spectrophotometric reagents—a review

The uses of oximes as spectrophotometric reagents since 1953 are reviewed.

Preparation and characterization of carboxylato derivatives of bis-(methyl cyclopentadienyl) titanium(IV)

Abstract Dicarboxylato complexes of bis-(methyl cyclopentadienyl) titanium(IV), of the type (CH 3 C 5 H 4 ) 2 TiA 2 (A = CH 3 COO, CH 3 CH 2 COO, CH 3 CH 2 CH 2 COO, C 6 H 5 COO, CH 2 ClCOO or CHCl 2 COO), have been prepared in aqueous as well as in nonaqueous medium, by the reaction of bis-(methyl cyclopentadienyl) titanium dichloride on appropriate sodium salt of the carboxylic acid. The carboxylato ligand is chelating and the carboxylato compounds are non electrolytic in nature. The bonding of carboxylato ligand in these complexes has been discussed and these complexes have been characterized by elemental analysis m.p. conductivity measurement and IR and NMR spectral studies.

Solid-phase extraction of metal ions and their estimation in vitamins, steel and milk using 3-hydroxy-2-methyl-1,4-naphthoquinone-immobilized silica gel

3-Hydroxy-2-methyl-1,4-naphthoquinone-immobilized silica gel has been used for the adsorption and estimation of copper, cobalt, iron and zinc by both batch and column techniques. The distribution coefficient D determined for each metal ion was as follows (ml g(1)): Fe, 3.6 x 10(2); Cu, 3.9 x 10(2); Co, 3.8 x 10(2); Zn, 4.1 x 10(2). Methods have been developed to estimate zinc, copper and cobalt in milk, steel and vitamin samples respectively.

Spectroscopic studies on copper(II) complexes derived from a substituted 2-acetylpyridine thiosemicarbazone

SummaryCopper(II) complexes of general formula [Cu(L4A)X] (where L4A is the deprotonated ligand, 1 H-hexahydroazepine-1-thiocarboxylic acid-2-[1-(2-pyridinyl)ethylidene]hydrazide and X=Cl, Br, I, NCS, NO3 and OAc) and [Cu(HL4A)(L4A)]ClO4 have been prepared and characterized by elemental analyses, magnetic susceptibility measurements, i.r. spectra, electronic spectra, conductivity measurements and e.s.r. spectra in the polycrystalline state and in chloroform solution. For all complexes, except the perchlorate salt, coordination occurs via imine nitrogen, pyridine nitrogen and thione sulphur. For the perchlorate salt, L4A is tridentate, while HL4A is monodentate via imine nitrogen. Electronic spectra suggest planar geometry for all the complexes. The calculated e.s.r parameters suggest coordination through sulphur in agreement with the i.r. results.

Analytical applications of thiosemicarbazones and semicarbazones

Abstract The analytical applications of thiosemicarbazones and semicarbazones in spectrophotometry, fluorometry, and atomic absorption spectrophotometry and as indicators have been reviewed (from January 1982 to November 1987). An account of the reagents has been given in this review and the reagents have been described in alphabetic order; all relevant data together with references are cited at the end.

Spectral studies of iron(III) complexes of substituted thiosemicarbazones of 2-acetylpyridine

SummaryIron(III) complexes of four substituted thiosemicarbazones of 2-acetylpyridine of general. formula [FeL2]ClO4 (where L is a deprotonated ligand) have been synthesised and characterised by elemental analyses, magnetic susceptibility measurements in the polycrystalline state at room temperature, i.r. spectra, electronic spectra and e.s.r. spectra recorded in polycrystalline state, in methanol solution at room temperature and at 77 K. All the complexes are 1:1 electrolytes. The ligands coordinate via the pyridine nitrogen, imine nitrogen and thione sulphur. E.s.r. spectra and with magnetic studies suggest a spin-paired configuration for the iron(III) complexes.

Separation and preconcentration of metal ions and their estimation in vitamin, steel and milk samples using o-vanillin-immobilized silica gel

o-Vanillin-immobilized silica gel has been used for the adsorption and estimation of copper, cobalt, iron and zinc by both batch and column techniques. Metal ions were quantitatively retained on the column packed with immobilized silica gel in the pH range 4.0-6.0 for Cu, 5.0-6.0 for Co, 4.5-6.0 for Fe and 6.0-8.0 for Zn. The distribution coefficient D determined for each metal was as follows (ml g(-1)): Fe, 5.4x10(2); Cu, 4.9x10(2); Zn, 4.4x10(2); Co, 3.8x10(2). Methods have been developed to estimate zinc, copper and cobalt in milk, steel and vitamin samples, respectively.

Characterization of copper(II) complexes of N4, N4-disubstituted thiosemicarbazones of 2-acetylpyridine by combined evaluation of electronic and ESR parameters

Abstract Copper(II) complexes of 2-acetylpyridine 4,4-dimethyl-3-thiosemicarbazone (L′H) and 2-acetylpyridine 4-(4-methylpiperidinyl)-3-thiosemicarbazone (LH) of the general formula CuLX (where L is a deprotonated ligand and X = F−, Cl−, Br−, I−, OAc− and NO−3) have been synthesized and characterized by elemental analysis, magnetic susceptibility measurements between 93 and 298 K in the polycrystalline state, i.r. spectra, electronic spectra, conductivity measurements and ESR spectra recorded in the polycrystalline state, in chloroform and dimethylformamide solution at room temperature and at 77K. The molar conductivities measured in dimethylformamide for all complexes show them to be non-electrolytes. The terdentate character of the ligands in all the complexes is inferred from i.r. spectral studies. The i.r. spectra also confirm the monodentate nature of the polyatomic anions such as nitrate and acetate. The electronic spectra in Nujol mulls, chloroform or dimethylformamide solution suggest planar geometry for all of the complexes. The calculated ESR parameters show an axial dx2−y2 ground state and suggest coordination through sulphur in agreement with the i.r. results. Little change in the value of g with temperature indicates no significant change in planarity of these four coordinated species. ESR spectra in solution at room temperature and 77 K also suggest a strong covalent environment with strong in-plane sigma and pi bonds provided by the ligands.

Manganese(II) complexes of substituted thio- and seleno- semicarbazones of 2-acetylpyridine: E.s.r., magnetic and electronic spectral studies

SummaryManganese(II) bis(ligand) complexes of substituted thiosemicarbazones and selenosemicarbazones derived from 2-acetylpyridine of general formula [MnL2] (where L=deprotonated ligand) have been synthesized and characterised by elemental analyses, electronic spectra in solution, i.r. spectra, magnetic measurements and e.s.r. spectra recorded in polycrystalline state and in solution at room temperature and 77K. The terdentate character of the ligands in all the complexes is inferred from i.r. spectra. The electronic spectra along with e.s.r. spectra suggest an octahedral environment around the manganese(II). The metal-ligand bonds are moderately covalent. Thus all the complexes reported here are six-coordinated and high-spin octahedral.