Arun Kumar Trikha

Synthesis and characterization of uranium(iv) compounds with piperazines

Abstract Compounds of the empirical formula [UX 4 · n (L)· m THF] (where X = thiocyanate, perchlorate, bromide and iodide; n = 1-3; L = piperazine, 1-methyl-, 2-methyl-, 1-phenyl-, 1,4-dimethyl-, 2,5-dimethyl- and 2,6-dimethylpiperazine; m = 0 and 1) have been prepared and characterized by physical studies. IR spectra indicate the mode of coordination. Electronic spectral and variable-temperature magnetic data have been employed to ascertain the stereochemical environment of uranium. Except for the perchlorate compounds, which are 1:1 electrolytes, all other compounds are non-electrlytes.

Complexes of thorium tetranitrate with N-methylpiperazine, 2-methylpiperazine, N-phenylpiperazine and N, N′-dimethylpiperazine

Abstract Complexes of Th(NO 3 ) 4 with the title ligands have been synthesised and characterised on the basis of elemental analyses and IR spectral studies which indicate that the ligands in the complexes are in chair conformation and the nitrate group is bidentate. Coordination number is higher than ten in all the complexes.

Emission spectra of europium(III) β-diketonate complexes with N-bases

Abstract The emission spectra of several compounds of europium(III) incorporating a variety of β-diketonates and N-bases have been examined in order to obtain reliable information relating to coordination number, nature of bonding and symmetry around the lanthanide ion. It has been found that steric factors may force the polyhedron of coordination towards geometries less favorable by ligand-ligand repulsion. In general no correlation has been found to exist between the intensity of the hypersensitive transitions and high or low symmetry.

Complexes of lanthanum(III) and cerium(III) with substituted piperazines

Abstract Complexes of LaCl 3 , CeCl 3 , La(NO 3 ) 3 and Ce(NO 3 ) 3 have been synthesized with N-methylpiperazine, 2-methylpiperazine, N-phenyl-piperazine and N,N′-dimethylpiperazine. These complexes, which are hygroscopic, were stored in vacuum-sealed ampoules and were prepared and handled in a dry bag. The complexes were characterized on the basis of elemental analyses, IR, electronic spectral data and magnetic susceptibility data. IR spectral data indicate that ligands probably coordinate in the chair form giving bridged polymeric complexes. The polymeric nature of the complexes is also suggested by the insolubility of the complexes in common organic solvents. It is possible that the coordination number of the lanthanide ion varies from six to nine in these complexes. An attempt has been made to assigny v (M-O) (in nitrate complexes) and v (M-N). The bidentate and monodentate nature of the coordinated nitrate ion is also discussed.

Synthesis and Characterisation of Some Uranium(VI) Complexes with Heterocyclic Bases

Abstract The synthesis of forty complexes of uranium(VI) of the general formula UO2X2. nL.mC2H5 OH where X = Br, I, NCS and C104; n = 0.5, 1 and 2; L = piperazine, 1-methylpiperazine, 2-methyl-piperazine, 1-phenylpiperazine, 2,5-dimethylpiperazine, 2,6-dimethylpiperazine, 1,4-dimethylpiperazine, 2-methylpiperidine, 3-methylpiperidine and 4-methylpiperidine and m = 0, 0.5, 1 and 2 is described. Elemental analyses, infrared spectra, molar conductance and thermogravimetric analysis (for some of the complexes only) have been used to characterise the complexes. The infrared spectral data show that the piperazines are coordinated in the chair form in all the complexes thus excluding the possibility of monomoric chelated complexes. The piperidines are coordinated in all the cases. The coordination of various anions and ethanol molecules have been discussed on the basis of infrared spectral studies and molar conductance measurements. Most complexes are insoluble in common organic solvents. They do not melt but de...

COMPLEXES OF URANIUM TETRACHLORIDE AND THORIUM TETRACHLORIDE WITH N‐METHYLPIPERAZINE, 2‐METHYLPIPERAZINE, N‐PHENYLPIPERAZINE, N,N′‐DIMETHYLPIPERAZINE, AND PYRAZINE

Abstract Stable complexes of uranium tetrachloride and thorium tetrachloride with the title ligands have been synthesised and characterised on the basis of elemental analyses, IR and electronic reflectance spectral studies and magnetic susceptibility measurements. The ligands probably coordinate in the chair conformation bridging the metal ions as indicated by IR spectral studies and insolubility of these complexes in common organic solvents. A coordination number of six for uranium (IV) is suggested by the electronic reflectance spectral and magnetic susceptibility data.

EUROPIUM(III) AND TERBIUM(III) β-DIKETONATE ADDUCTS WITH 2,6-DIMETHYLMORPHOLINE: SYNTHESIS, CHARACTERIZATION AND EMISSION SPECTRA

Abstract Complexes with composition Ln2(β-diketonate)6 (dmm) (Ln = Eu, Tb; dmm = 2,6-dimethyl-morpholine; β-diketonate = 4,4,4-trifluoro-l-(2-thienyl)-l,3-butanodionate (tta); 4,4,4-tri-fluoro-1-phenyl-1,3-butanodionate (tfpb) and l,l,l-trifluoro-l,4-pentanedionate (tfa)) have been synthesized. The adducts were characterized by microanalyses, IR spectra and emission spectra at room temperature and at 77K. The spectra of europium complexes indicate the oligomeric at least dimeric, nature of the compounds, since the bands are broad. The number of peaks in all cases was interpreted as C3V symmetry around the central ion.

Uranium(VI) Compounds Containing 1-Butyl-1-methyl-piperazinium Iodide: Synthesis and Characterisation

Abstract The white crystalline mono-quaternized diamine salt, 1-butyl-1-methylpiperazinium iodide, obtained by reacting 1-methylpiperazine and butyl iodide, reacts with uranyl acetate, nitrate, perchlorate, sulphate, thiocyanate, chloride, bromide and iodide in 1:1, 1:2 and 1:6 molar ratios giving products of varying stoichiometries. The complexes have been characterised on the basis of analytical data and infrared spectra. Infrared spectral studies show that only one of the nitrogens (the NCH3 nitrogen) is quaternized and the quaternary salt is coordinated to the uranyl group through the NH nitrogen; the mode of coordination of various anions is also indicated. Coordination numbers varying from 5 to 9 are proposed for the metal ion in these complexes.

Synthesis and characterisation of uranium(IV) nitrate complexes with piperazines

Uranium(IV) complexes of empirical formula U(NO3)4L2(L = piperazine, 1-methyl-, 2-methyl-, 1-phenyl-, 1,4-dimethyl-, 2,6-dimethyl-, or 2,5-dimethyl-piperazine) have been prepared by a new method involving the in situ reaction of uranium(IV) nitrate with the ligands. Infrared spectral studies indicate the nitrate groups to be co-ordinated in a chelating bidentate fashion and the piperazines in a chair conformation. The electronic spectra and magnetic properties are also discussed.

Investigations on Compounds of Uranium(IV) with Picoline-N-Oxides

Abstract Eighteen compounds of the empirical formulas UX4LnmC2H5OH and UX4Ln.mTHF where X=C1−, Br−, I−, NCS−, NO3, and CIO4; h=l,2,3; L=2-picoline-N-oxide,3-picoline-N-oxide and 4-picoline-N-oxide and m=0 and 2 have been synthesised and characterised by various physical studies. Infrared spectra indicate the modes of coordination. Electronic spectral studies have been performed to ascertain the coordination number(eight) of uranium. Variable temperature magnetic measurements also have been made. Except the nitrate and iodide compounds which are 1:1 electrolytes, all other compounds are non-electrolytes.