• T R Rao

      Articles written in Journal of Chemical Sciences

    • Magnetic and spectral studies on 3d-metal complexes of acetone(N-isopropylidene)tyrosyl hydrazone

      T R Rao Mamta Sahay R C Aggarwal

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      Acetone(N-isopropylidene)tyrosyl hydrazone, HO-C6H4-CH2-CH(N=CMe2)-CONHN=CMe2 (ath), has been found to form adducts of the typeM (ath) Cl2·nH2O [M = Mn (II), Co (II), Ni (II), Cu (II) and Zn (II);n = 0, 1 or 2] and deprotonated complexes of the type M′(ath-2H) · 3H2O[M′ = Co(II), Ni(II) and Cu(II)]. Molar conductance studies in 0.001 Mdmso solution have indicated the non-ionic nature of the complexes. High-spin octahedral geometry for Mn(II) and Ni(II) complexes and tetrahedral geometry for Co(II) adduct have been proposed on the basis of magnetic and/or electronic spectral studies.ir spectra suggest neutral bidentate and dinegative tridentate behaviour of the ligand in the adducts and deprotonated complexes respectively,esr spectra of Cu(II) complexes indicate zero-field splitting of Cu(ath)C12 · H2O and metal-metal interaction in both the complexes.

    • Synthetic and structural studies of some trivalent lanthanide metal complexes ofo-hydroxyacetophenone (N-benzoyl)glycyl hydrazone

      T R Rao Genda Singh

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      o-Hydroxyacetophenone (N-benzoyl)glycyl hydrazone (o-HABzGH) forms complexes of the types [M(o-HABzGH)Cl2(H2O)2]Cl and [M(o-HABzGH-2H)OH(H2O)2], where M = Y(III), Gd(III), Tb(III) and Dy(III). The complexes have been characterized by elemental analyses, molar conductance, magnetic susceptibility, infrared, electronic,1H NMR and13C NMR spectral techniques. The nephelauxetic ratio (β), covalency (δ), bonding parameter (b1/2) and angular overlap parameter (η) have been calculated from Dy(III) complexes. Infrared and NMR spectral studies show thato-HABzGH acts as a neutral bidentate ligand in the adduct complexes and as a dinegative tridentate one in the neutral complexes. A coordination number of six has been proposed for the metal ion in all the complexes.

    • Studies on 2-acetylpyridineisonicotinoyl hydrazone complexes of some bivalent 3d-metal ions

      Pariti S S J Sastry T R Rao

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      2-Acetylpyridineisonicotinoyl hydrazone (Hapinh) complexes of OV(II), Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) having 1:1 metal-ligand stoichiometry have been prepared and characterised by elemental analyses, molar conductance, magnetic susceptibility, electronic, infrared, ESR and NMR (1H and13C) studies. Octahedral/distorted octahedral geometry has been assigned for the OV(II), Mn(II), Ni(II), Cu(II) and Zn(II) complexes while tetrahedral and trigonal bipyramidal configurations have been suggested for the Co (II) adduct and deprotonated complexes respectively. IR and NMR spectral studies suggest a tridentate behaviour of Hapinh and apinh species in the adducts and deprotonated complexes respectively.

    • Protonation constant of salicylidene (N-benzoyl)glycyl hydrazone and its coordination behaviour towards some bivalent metal ions

      R K Lonibala T R Rao R K Babita Devi

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      Protonation constant of an unsymmetrical Schiff base, salicylidene(N-benzoyl)glycyl hydrazone (SalBzGH), and formation constants of its complexes have been determined potentiometrically at different temperatures in aqueous dioxane medium. Complexes of SalBzGH with VO(IV), Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and Hg(II) have been prepared. Elemental analyses, pH-metric, molar conductance, magnetic susceptibility, electronic, IR, ESR, XRD (powder) and NMR studies have been carried out to study the coordination behaviour of SalBzGH toward these metal ions. pH-metric and 1H NMR studies show the presence of two dissociable protons in the ligand. IR and NMR spectra suggest the tridentate nature of the ligand, coordinating as a uninegative species in the Mn(II) complex and as a dinegative species in all the other complexes. Presence of two different conformers of the ligand at room temperature and stabilization of a single conformer upon complex formation have been established from1H NMR spectra of the metal-free ligand, Zn(II) and Hg(II) complexes recorded at 296 K. Electronic and ESR spectra indicate highly distorted tetragonal geometry for VO(IV) and Cu(II) complexes. XRD powder patterns of the Zn(II) complexes are indexed for an orthorhombic crystal system.

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