http://nopr.niscpr.res.in/handle/123456789/40391 2026-10-07T16:12:07Z http://nopr.niscpr.res.in/handle/123456789/41174 Title: <i>Ab initio</i> MO studies of nuclear spin-spin interactions in NH<img src='http://www.niscair.res.in/jinfo/two.gif' border=0>, NH₃, NH<img src='http://www.niscair.res.in/jinfo/plusfour.gif' border=0> and N₂H₄ Authors: Chandak, Madhulika; Chakraborty, Dhrubadas; Chandra, P Abstract: Indirect spin-spin coupling constants in NH<img src='http://www.niscair.res.in/jinfo/two.gif' border=0>, NH₃, NH<img src='http://www.niscair.res.in/jinfo/plusfour.gif' border=0> and N₂H₄ have been calculated employing the SCF perturbation theory at the ab initio level. For N the (10s6p) basis set of Dunning, which is contracted to [5<i>s</i>3<i>p</i>], has been used while the same author's (5<i>s</i>) basis set of H is contracted to [3<i>s</i>]. In all the calculations basis sets have been augmented with bond centred functions, or nuclear centred higher angular momentum functions, or both. In addition, the consequence of decontraction of basis sets, particularly <i>s</i> functions, is tested. For all practical purposes, a basis set containing bond functions along with uncontracted innermost <i>s</i> function yields good results. For the vicinal couplings, the basis set need not necessarily be large as these couplings are insensitive to the size of the basis set. Page(s): 1049-1057 1994-12-01T00:00:00Z http://nopr.niscpr.res.in/handle/123456789/41173 Title: Acid-base equilibria of some salicylatopentaminecobalt (III) ions in mixed solvent media: An attempt to study molecular recognition Authors: Dash, Anadi C; Jena, Kishore C; Acharya, Achyuta N Abstract: The study of the acid-base equilibria of <i>cis</i>-[Co(en)₂(RNH₂)O₂CC₆H₄OH]²⁺] (R=H, CH₃, CH₃CH₂) in methanol-water, propan-2-ol-water, terr-butanol-water, acetone-water, and ethylene glycol-water (0 <img src='http://www.niscair.res.in/jinfo/lessequals.gif' border=0> vol% organic solvent <img src='http://www.niscair.res.in/jinfo/lessequals.gif' border=0> 70) are reported at 25°C. The transfer free energy of the phenol fonn relative to that of phenoxide form of the complexes, where transfer occurs from water to the- mixed solvents, have been evaluated. Solubility studies for the sparingly soluble dithionate salt of the phenol form of these complexes have been made in methanol-water media at 25°C and the transfer free. energy of the phenol and phenoxide species (relative to water) have been assessed. Results highlight theelectrostatic and nonelectrostatic medium effects on the solvation of the phenol and phenoxide species of the complexes. The transfer free energy data suggest that the complex ions recognise the cosolvent molecules in their Gurney cosphere via both coulombic and hydrophobic interactions. Page(s): 1058-1062 1994-12-01T00:00:00Z http://nopr.niscpr.res.in/handle/123456789/41172 Title: Synthesis and characterization of cyclopentadienylzirconium 1-pyrrolecarbothioates and -dithioates Authors: Bhattacharya, S; Gupta, V D; Polborn, K; Noth, H Abstract: Three series of complexes, viz; <i>bis</i>(<i>η</i>⁵-cyclopentadienyl) zirconium 1-pyrrolecarbothioates and -dithioate, <i>bis</i>(<i>η</i>⁵-cyclopentadienyl)aryloxyzirconium 1-pyrrolecarbodithioates and <i>η</i>⁵-cyclopentadienylzirconium 1-pyrrolecarbodithioates have been synthesized and characterized by infrared and IH NMR spectroscopy. The complex Cp₂ZrCI(S₂CNC₄H₄) (II) crystallizes in the monoclinic space group P2₁/n. The molecular structure reveals a bent metallocene structure with the S<img src='http://www.niscair.res.in/jinfo/twobar.gif' border=0>CNC₄H₄ ligand bidentately bonded to the Zr atom. Page(s): 1063-1068 1994-12-01T00:00:00Z http://nopr.niscpr.res.in/handle/123456789/41171 Title: Application of Kirkwood-Buff theory of liquid mixtures to binary aqueous solutions of alcohols Authors: Patil, K J; Mehta, G R; Dhondge, S S Abstract: The various integrals over the pair correlation functions, G_AA, G_ww and G_AW (A=alcohol, W= water) have been calculated for aqueous solutions of methanol, ethanol, 1-propanol and tertbutanol at 25°C by utilizing the thermodynamic properties like the isothermal compressibility, partial molar volumes and vapour pressure and by the application of an inverse procedure for KirkwoodBuff theory of solutions as suggested by Ben-Nairn. It is observed that as a function of concentration, G_AA, G_AW and G_ww have extremas in the studied concentration range. The results are compared with similar systems reported earlier and are interpreted on the basis of solvent structural effects and hydrophobic interaction amongst the solute molecules. The behaviour of GAA in dilute concentration indicates that the strength of hydrophobic interaction decreases initially in all the studied water-alcohol systems. The mean square concentration fluctuation parameter N < (<img src='/image/spc_char/delta.gif' border=0>x)² > as a function of concentration has been estimated using G_ij values. These results are in agreement with the available scattering data, suggesting further that the main effect of alcohol is to interfere destructively with low density domains in water in dilute concentration of alcohols in water. Page(s): 1069-1074 1994-12-01T00:00:00Z