Standard enthalpies of formation of [Ln(Gly)3(H2O)2]Cl3•2H2O (Ln = Pr, Nd; Gly = glycine):: A calorimetric study

Crystals of two coordination compounds of rare earth chlorides with glycine, [Ln(Gly)(3)(H2O)(2)]Cl-3.2H(2)O (Ln = Pr, Nd; Gly = glycine), were prepared and characterized. Using a solution-reaction isoperibol calorimeter, the standard molar enthalpies of reaction for the general thermochemical reaction, LnCl(3). 6H(2)O(S) + 3Gly(s) = [Ln(Gly)(3)(H2O)(2)]Cl-3.2H(2)O(cr) + 2H(2)O(l) (Ln = Pr, Nd; Gly = glycine), were determined at T = 298.15 K, as (19.2 +/- 0.4) kJ.mol(-1) and (63.4 +/- 0.5) kJ.mol(-1), respectively. From the above standard molar enthalpies of reaction and other auxiliary thermodynamic quantities, the standard molar enthalpies of formation of [Ln(Gly)(3)(H2O)(2)]Cl-3.2H(2)O (Ln = Pr, Nd; Gly = glycine), at T = 298.15 K, have been derived to be -(3875.7 +/- 1.1) kJ.mol(-1) and -(3825.2 +/- 1.1) kJ.mol(-1), respectively.