A. Cassol, P. Bernardo, R. Portanova
Sep 30, 1997
Citations
0
Influential Citations
14
Citations
Journal
Inorganica Chimica Acta
Abstract
Abstract The thermodynamic parameters for the dissociation in acetonitrile of the tris-trifluoromethanesulfonates of the heavier lanthanides according to the equilibrium Ln(tri) 2 + +tri − ⇌Ln(tri) 3 (Ln=Tb–Lu; tri − =CF 3 SO 3 − ) are reported. Potentiometric, calorimetric, conductometric and FT-IR measurements show that in acetonitrile both Ln(tri) 3 and Ln(tri) 2 + form with n-butylamine at least four strong, mononuclear, successive complexes whose stability seems to be not very dependent upon the acceptor charge. The bonding of n-butylamine occurs with a preferential loss of solvent molecules from the coordination sphere of the metal ion rather than with release of triflate ions. The equilibria of formation of ternary complexes Ln(tri) n but m (3− n )+ (but=n-butylamine; n =2 or 3; m =1–4) are qualitatively interpreted in terms of the different factors affecting the ion–ion and ion–dipole interactions. Apparent stability constants and the related thermodynamic values concerning the complexing ability toward n-butylamine of a system containing Ln(tri) 3 and Ln(tri) 2 + are given.