Résumé
The syntheses of Pr(ClO 4 ) 3 , Pr(OTf) 3 (OTf = CF 3 SO 3 ), Pr(ClO 4 ) 3 •Cl 2 O 6 , and NO 2 Pr(ClO 4 ) 4 are described. Vibrational spectroscopy, X-ray powder diffraction, and EXAFS (for Pr(ClO 4 ) 3 ) are used to characterize the structure of the complexes. [ClO 4 ] and [OTf] appear as tridentate in Pr(ClO 4 ) 3 and Pr(OTf) 3 and Pr is 9-coordinated. In Pr(ClO 4 ) 3 •Cl 2 O 6 , chlorine trioxide is included in the lattice of Pr(ClO 4 ) 3 and shows the ionic ↔ covalent equilibrium. In NO 2 Pr(ClO 4 ) 4 , Pr(ClO 4 ) 4 − retains the structure of Pr(ClO 4 ) 3 , the extra [ClO 4 ] is weakly bonded to Pr • Pr(ClO 4 ) 3 crystallizes in the monoclinic system (P2 1 /m), a = 8.608; b = 11.827; c = 7.416 Å; β = 106.29°, and V = 724.79 Å 3 . Distances Pr—O = 2.51 Å and Pr—Cl = 3.90 Å are determined by EXAFS. Strong fluorescence phenomena are observed when Pr(ClO 4 ) 3 is excited with the 488 nm line of an ionized Ar laser.