G. Oczko et P. Starynowicz, Crystal structure and absorption spectroscopy of Ln(HF2CCOO)(3)center dot 3H(2)O (Ln = Pr, Er) single crystals, J MOL STRUC, 523, 2000, pp. 79-91
Crystal structures of Ln(HF2CCOO)(3).3H(2)O (Ln = Pr, Er) compounds were de
termined by X-ray analysis. Both crystals proved to be isomorphous. They ar
e triclinic, space group P (1) over bar, with a = 8.394(2) Angstrom, b = 9.
509(2) Angstrom, c = 9.623(2) Angstrom, a = 66.60(2)degrees, beta = 79.34(2
)degrees, gamma = 77.74(2)degrees and Z = 2 for the Pr compound and a = 8.2
58(2) Angstrom, b = 9.358(2) Angstrom, c = 9.458(2) Angstrom, alpha = 66.90
(2)degrees, beta = 79.34(2)degrees, gamma = 77.80(2)degrees and Z = 2 for t
he Pr one. The Ln(III) ion adopts an 8-coordinate geometry with six oxygen
atoms from carboxylate groups and two oxygen atoms from water molecules, wh
ich is best described as the best slightly deformed square antiprism. Absor
ption spectra of the Pr(HF2CCOO)(3).3H(2)O single crystal were measured at
room and low temperatures. Intensities of the f-f transitions were analysed
on the basis of the Judd-Ofelt theory. The results for the praseodymium di
fluoroacetate single crystals are compared to those for the lanthanide trif
luoroacetates monocrystals. Vibronic mechanism of 4f-4f transitions is disc
ussed. (C) 2000 Elsevier Science B.V. All rights reserved.