SYNTHESIS, STRUCTURAL AND SPECTROSCOPIC PROPERTIES OF TETRA(TETRAETHYLAMMONIUM) HEPTAISOTHIOCYANATO URANATE(III) AND NEODYMATE(III)

The synthesis and characterization of a new uranium(III) compound and its neodymium(III) analogue of the formulas [(C2H5)(4)N]U-4(NCS)(7) (I ) and [(C2H5)(4)N]Nd-4(NCS)(7) (II) are reported. Both compounds are i somorphic and crystallize in the tetragonal system, space group I4/mmm with: a = 11.530 Angstrom, c = 45.555 Angstrom, Z = 4, V = 6056.1 Ang strom(3) (1) and a = 11.564(2) Angstrom, c = 45.801(9) Angstrom, Z = 4 , V = 6125.0(9) Angstrom(3) (II). The IR, Raman and electronic spectra of the compounds have been recorded in the 30-4000 cm(-1) and 4000-30 000 cm(-1) spectral ranges, respectively, and are further discussed. The assignments of the IR and Raman frequencies based on theoretical c onsiderations are given.