Regularity of Thermochemical Properties of Ternary Complexes RE[(pdtc)3(phen)]
Abstract
Treatment of hydrate rare-earth (RE=La, Pr, Nd, Sm-Lu) chloride with ammonium pyrrolidinyldithiocarboxylate (apdtc) and 1,10-phenanthroline (phen) gave rise to thirteen complexes with an empirical formula RE[(pdtc)3(phen)]. The enthalpies of solution of hydrate rare-earth (RE=Sm-Ho, Tm-Lu) chloride, apdtc and phen in ethanol were measured by an RD-496 ?? microcalorimeter at 298.15 K, along with the mixing enthalpy of ethanol solution of APDC and that of phen and the enthalpies of reaction of formation of the title complexes in ethanol. The enthalpies of reaction of formation of the title complexes in solid were available through a rationally thermochemical cycle. Using an RD-496 ?? microcalorimeter, a model was developed for calculating the specific heat capacity and the responding specific heat capacity of the complexes were determined. The thermochemical properties, including the enthalpies of solution of hydrate rare earth chloride in ethanol, the enthalpies of reaction of formation of the title complexes in ethanol, the enthalpies of reaction of formation of the title complexes in solid, the special heat capacities at room temperature, the standard molar enthalpies of combustion and the standard molar enthalpies of formation for this series of complexes versus the atomic numbers of rare earth, presented triplet effect, which is representative of certain covalent bond between RE and the ligands and the result of 4f electron not shielded fully by 5s5p.
