Jean-Claude Bunzli - Ft-Ir and Fluorometric Investigation of Rare-Earth and Metal-Ion Solvation .11. Interaction Between Dmso and Lanthanide Perchlorates in Anhydrous Acetonitrile

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  MilicicTang,A., Bunzli,J.C.G. Inorganica Chimica Acta  1992 192 (2) 201-209

  Abstract: The interaction between DMSO and   lanthanide perchlorates in anhydrous acetonitrile has been   investigated by FT-IR and Raman spectroscopy. A quantitative   study was performed on 0.05 M solutions with R = [DMSO]t/[Ln]t =   7-20. The upsilon-7(S-O) vibration of DMSO was used to determine   the concentration of free DMSO in solution. None of the   investigated systems shows any interaction with either   perchlorate ions or acetonitrile molecules. The average   coordination number (CN) of the Ln(III) ions is therefore equal   to the average number of bonded DMSO molecules. Changes in   coordination numbers are observed both with increasing atomic   number and with the solvent composition. The data may be   interpreted in terms of equilibria between six-, seven-, eight-,   nine- and ten-coordinate species. For R = 8, a gradual change is   observed between 7.8 (La) and 6.6 (Lu). For R = 12 and 15, the   overall change amounts to 1.3 (8.7-7.4) and 1.7 units (9.7-8.0),   respectively, but in addition, a clear discontinuity is observed   at Gd (c. 1 unit). For R = 15, additional breaks (c. 0.5 unit)   occur around Nd and Er. For a single ion, changes in coordination   number with increasing DMSO composition (R = 7-15) amounts to   almost 2 units for lighter Ln ions and to 1.0-1.2 units for   heavier ions. All the DMSO molecules in the inner-coordination   sphere appear to be equivalent, so that the increase in CN is   interpreted in terms of an expansion of the first coordination   sphere to accommodate additional donor molecules. Equilibrium   constants have been estimated from the average CNs. They vary   between log K8 = 2.2 (La) to 0.6 (Lu), log K9 = 1 (La) to 0.4   (Lu) and log K10 = 0.9 (La) to 0.3 (Sm)

  Address (URL): WOS:A1992HT93500010