Synthèses et caractérisations structurales de complexes perchlorato et triflato anhydres de praseodyme(III)

Abstract

The syntheses of Pr(ClO4)3, Pr(OTf)3 (OTf = CF3SO3), Pr(ClO4)3•Cl2O6, and NO2Pr(ClO4)4 are described. Vibrational spectroscopy, X-ray powder diffraction, and EXAFS (for Pr(ClO4)3) are used to characterize the structure of the complexes. [ClO4] and [OTf] appear as tridentate in Pr(ClO4)3 and Pr(OTf)3 and Pr is 9-coordinated. In Pr(ClO4)3•Cl2O6, chlorine trioxide is included in the lattice of Pr(ClO4)3 and shows the ionic ↔ covalent equilibrium. In NO2Pr(ClO4)4, Pr(ClO4)4− retains the structure of Pr(ClO4)3, the extra [ClO4] is weakly bonded to Pr• Pr(ClO4)3 crystallizes in the monoclinic system (P21/m), a = 8.608; b = 11.827; c = 7.416 Å; β = 106.29°, and V = 724.79 Å3. Distances Pr—O = 2.51 Å and Pr—Cl = 3.90 Å are determined by EXAFS. Strong fluorescence phenomena are observed when Pr(ClO4)3 is excited with the 488 nm line of an ionized Ar laser.