The thermodynamic properties of rare-earth metal binuclear acetates and pivalates

The temperature dependence of the heat capacities of binuclear acetates M2(η1,η2-OOCCH3)2(η2-OOCCH3)4(H2O)4 · xH2O (M = La(1), Sm(2), Eu(3), and Tm(4)) (113−330 K); pivalates M2(μ2-OOCCMe3)4(OOCCMe3)2(HOOCCMe3)4·HOOCCMe3 (M=La(5), Sm(6), and Eu(7)) (113−320 K); and intermediate products of their thermal decomposition M2(OOCCH3)6(113–330 K) and M2(OOCCMe3)6 (113–500 K) and enthalpy changes at particular decomposition stages were determined by differential scanning calorimetry. The composition of the solid phase formed in decomposition was determined experimentally. The complete set of thermodynamic data was obtained, including Cp(T), S°(298), ΔfH°(298), and ΔfG°(298), for binuclear lanthanide acetates and pivalates specified above. The composition of the gas phase formed in decomposition was determined, which allowed us to suggest a resultant scheme of the thermal destruction of pivalates. The reliability of this scheme was demonstrated.