Proceedings of the Indian Academy of Sciences - Chemical Sciences

Datta, Dipankar

doi: 10.1007/BF02862946pmid: N/A

Ligand based redox series intris-bipyridyl complexes ofd 6 metal ions andtris-o-semiquinone complex of Cr (III) follow a general pattern. It is demonstrated that it is possible to look for a isothermodynamic proton transfer series. In the present study orthophosphoric acid is singled out. Implications of such correlations are discussed.

Varshney, Anil; Tandon, J

doi: 10.1007/BF02862945pmid: N/A

Some new adducts of tin(II) have been synthesized by the reaction of anhydrous stannous chloride with monofunctional bidentate and bifunctional tetradentate Schiff bases in an oxygen-free nitrogen atmosphere using tetrahydrofuran as the reaction medium. An attempt has been made to probe their structures by elemental analyses, molecular weight determination, conductivity measurement, and IR1H NMR and Mössbauer spectra.

Merchant, J; Waghulde, Vidyullata

doi: 10.1007/BF02862950pmid: N/A

Synthetically useful substituted hexahydrobenzofluoren-11-ones and tetrahydropentalenonaphthalen-10(H)-ones are prepared in one step by the reaction of cyclic α, β-unsaturated acids, namely, 1-cyclohexene.-1-carboxylic acid and 1-cyclopentene-1-carboxylic acid, with substituted dialkoxynaphthalenes in the presence of polyphosphoric acid. The stereochemistry at the C/D ring junction is determined from the1H NMR and by decoupling experiments.

Yatirajam, V; Khaira, Sirpal; Kakkar, L

doi: 10.1007/BF02862943pmid: N/A

In hydrochloric acid medium, rhenium is reduced to a lower valence using stannous chloride as a reductant. The reduced species of the metal ion forms a stable violet coloured complex with potassium ferrocyanide on heating, which can be quantitatively extracted into isoamyl alcohol and its absorbance measured. The method is free from the interference of anions like sulphate, chloride, oxalate, tartrate and EDTA. Microamounts of U(VI), Cr(VI,III), V(V), Fe(III,II), Cu(II), Co(II), Ni(II), Zn(II) and Pd(II) also do not interfere. The method has a wider Beer's law range of 0–20 μg Re/ml with a Sandell's sensitivity of 0·022 μg/cm2, and is successfully applied to the analysis of different synthetic samples containing micro amounts of rhenium where it compares favourably with the existing methods. The ratio of rhenium: ferrocyanide in the extracted species is found to be 1∶1 by Job's method of continuous variations and confirmed by the mole ratio method.

Rao, T; Khan, I

doi: 10.1007/BF02862947pmid: N/A

Tyrosine hydrazide (TH) has been found to form complexes of the types [M(TH)3Cl2]Cl [M=La(III), Pr(III), Nd(III)] and [M′(TH)2Cl2]Cl [M′=Sm(III), Eu(III), Gd(III) and Dy(III)]. The complexes have been characterized by elemental analysis, molar conductance, magnetic susceptibility, infrared, electronic and PMR spectral studies. The nephelauxetic ratio (β), covalency (δ) and bonding parameter, (b 1/2) of [Nd(TH)3Cl2]Cl have been calculated. Infrared spectral studies reveal that TH acts as a neutral bidentate ligand. Coordination numbers of eight around La(III), Pr(III) and Nd(III) and six around Sm(III), Eu(III), Gd(III) and Dy(III) have been proposed in the complexes.

Pathak, Gopal; Patil, K; Pradhan, S

doi: 10.1007/BF02862953pmid: N/A

The excess volume of mixing for 1-aminobutane, 2-aminobutane, 1-amino-2-methylpropane and 2-amino-2-methylpropane with chloroform were determined at 30° by the density method. TheV E were negative for all the systems and showed the following order: 2-amino-2-methylpropane>2-aminobutane>1-amino-2-methylpropane>1-aminobutane. The negativeV E were attributed to complex formation between the amine and chloroform molecules owing to H bonding, while the particular trend was attributed to the decreasing degree of self-association of amine isomers.

Ganguly, P; Rao, C

doi: 10.1007/BF02862956pmid: N/A

Joshi, V; Gijare, A

doi: 10.1007/BF02862942pmid: N/A

Ten amino acid complexes of platinum (II) and palladium (II) of the type [M(L−L)(a−a)]Cl (where M=Pt or Pd; L−L=bidentate polypyridyl chelating agents and a−a=amino acids, S-methyl-L-cysteine or L-methionine) have been synthesized and characterized by various physical methods. The conductivity data show that these complexes are 1∶1 electrolytes and confirm the above formation. The ultraviolet spectra of these complexes show π-π* bands of polypyridyl ligands and MLCT bands, whiled−d bands are obscured. The1H NMR spectra of these complexes show that the amino acids are bonded to platinum and palladium through nitrogen and sulphur atoms. The infrared data have further supported the above bidentate mode of binding of the amino acids while the carboxylate group of the amino acids remains uncoordinated and deprotonated in these complexes. The S-methyl-L-cysteine complexes exist as diastereoisomers due to the presence of a chiral sulphur atom as identified by1H NMR.

Tyagi, Suresh

doi: 10.1007/BF02862948pmid: N/A

Studies on electron transfer in (tspc)Co(II)-apoMb and (tspc)Fe(II)-apoMb were carried out as a function of PH by using optically transparent thin layer electrodes. (tspc)Co(II)-apoMb goes to two-stage oxidation-reduction equilibria, whereas, (tspc)Fe(II)-apoMb is stabilized by the protein itself. The mechanism proposed for stabilization of (tspc)Fe(II)-apoMb is the ligand-metal charge transfer from the imidazole of the histidine residue of protein to the central Fe ion of (tspc)Fe(III)-apoMb. The formation of a super-oxide is proposed for the oxygenation of (tspc)Co(II)-apoMb. The reduction potential of (tspc)Co(II)-apoMb⇌(tspc)Co(III)-apoMb, using ferrocene mono carboxylic acid as mediator, is reported, as also the reduction potential for (tspc)Co(II)-apoMb⇌(tspc)Co(I)-apoMb, using Ru(NH3)6Cl3 as mediator. The dependence ofE 1/2 obs on pH indicates the presence of the ionizable functional groups on the protein, which undergo ionization when the protein changes from the reduced to the oxidised form. TheK ox andK red parameters were calculated and are reported here.

Mustofy, H; De, G

doi: 10.1007/BF02862944pmid: N/A

The kinetics of substitution of aquo ligands from hydroxopentaaquo chromium (III) ion by L-histidine in water ethanol medium has been studied spectrophotometrically. The rate law involving the ion pair formation has been established. The activation parameters have been calculated and compared with other substitution reactions. Variation of dielectric constant of the medium was used as a tool for the mechanistic conclusion. Considering all the results, a mechanism involving the prior formation of ion pair followed by associative interchange (I a) has been suggested.