4 resultados para Age, Uranium-Thorium

em Indian Institute of Science - Bangalore - Índia


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U, Th and K contents of gneisses, granites and pegmatites of the Precambrian shield complex of S. E. Mysore have been determined by gamma ray spectrometry. Th/U ratios in most gneisses and granites are found to have values in the range 5–15, being higher than the accepted value of about 3.5 for crustal material.

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Antipyrine complexes of TiO2+, ZrO2+, Zr4+, Th4+ and UO2+2 perchlorates with molecular formulae TiO(Apy)4(ClO4)2, ZrO(Apy)3(ClO4)2, Zr(Apy)6(ClO4)4, Th(Apy)7(ClO4)4 and UO2(Apy)5(ClO4)2 have been prepared and characterized. The complexes are stable in air at room temperature and decompose exothermally at ~3OO °C. The i.r. study indicates the bonding of the antipyrine to the metal ion through its carbonyl oxygen. The nature of the bonding of the perchlorate and the stereochemistry of the complexes are discussed in the light of infrared spectra, conductivity in solvents of different polarity, and molecular weight measurements. From the UO2+2 group frequencies, the force constant K and rU-o are found to be 6.29 × 105 dynes/ cm-1 and 1.74 Å, respectively.

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Three new phosphonoacetate hybrid frameworks based on the actinide elements uranium and thorium have been synthesized. The compounds [C4N2H14][(UO2)(2)(O3PCH2COO)(2)]center dot H2O, I,[C4N2H14][(UO2)(2)(C2O4)(O3PCH2COOH)(2)], II, and Th(H2O)(2)(O3PCH2COO)(C2O4)(0.5). H2O, III, are built up from the connectivity between the metal polyhedra and the phosphonoacetate/oxalate units. Compound II has been prepared using a solvent-free approach, by a solid state reaction at 150 degrees C. It has been shown that II can also be prepared through a room temperature mechanochemical (grinding) route. The layer arrangement in III closely resembles to that observed in I. The compounds have been characterized by powder X-ray diffraction, IR spectroscopy, thermogravimetric analysis, and fluorescence studies.

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Co-ordination complexes of the diphosphazane dioxides Ph(2)P(O)N(Pr-i)P(O)Ph(2) L(1). Ph(2)P(O)N(Pr-i)P(O)Ph(OC(6)H(4)Me-4) L(2) and Ph(2)P(O)N(Pr-i)P(O)(O2C12H8) L(3) with UO22+ or Th4+ ions have been synthesised and characterised by IR and NMR spectroscopy. The structures of [UO2(NO3)(2)L(1)] and [Th(NO3)(2)L(3)(1)][Th(NO3)(6)] are established by X-ray crystallography. In the former, the uranyl ion is bonded to two bidentate nitrate groups and the two phosphoryl groups of the ligand L(1); the co-ordination polyhedron around the metal is a hexagonal bipyramid. The cationic moiety in the thorium complex contains three bidentate diphosphazane dioxide ligands and two bidentate nitrate groups around the ten-co-ordinated metal.