Vibrational dynamics and nature of the double halide bridges for the example of solid A(2)UX(5) uranium(III) ternary systems (A = K, Rb; X = Cl, Br and I)

Infrared and Raman scattering spectra of solid ternary A(2)UX(5) (A = K, Rb ; X = Cl, Br, I) uranium(III) halides have been measured in the 50-500 cm(- 1) spectral range. A factor group analysis has been used to identify the en ergy and symmetry of the observed modes. The assignment of the phonons to t he respective molecular vibrations has been performed on the basis of the n ormal coordinate analysis. The Urey-Bradley Force Field and the Potential E nergy Distribution were applied. The vibrational characteristics of the hal ide double bridges, i.e., energy, symmetry, force constants, potential ener gy distribution, atomic displacements, direction of the transition dipole m oments and mean square amplitudes have been collected and are discussed. Th e influence of the bridging system on the electronic properties of the comp lex compound studied has been analysed. (C) 1999 Elsevier Science B.V. All rights reserved.