Thermochemistry of the solid-state coordination compounds (C2H10N2)MCl4(s) (M = Cd and Cu)

Tetrachlorocuprate (II) ethylenediammonium (C2H10N2)CuCl4(s) and tetrachlorocadmate (II) ethylenediammonium (C2H10N2)CdCl4(s) were synthesized. Chemical analysis, elemental analysis, and X-ray crystallography were applied to characterize the compositions and crystal structures of the two complexes. In accordance with Hess law, two thermochemical cycles were designed, and the enthalpy changes of the reactions of ethylenediamine dihydrochloride with CuCl2·2H2O(s) and CdCl2·2.5H2O(s) were determined as ΔrHm,1∘=(5.89±0.22)kJ·mol-1 and ΔrHm,2∘=-(2.88±0.26)kJ·mol-1 by use of an isoperibol solution–reaction calorimeter, respectively. The standard molar enthalpies of formation of the title complexes (C2H10N2)CuCl4(s) and (C2H10N2)CdCl4(s) were derived to be ΔfHm∘ [(C2H10N2)CuCl4, s] = −(784.51 ± 1.35) kJ · mol−1 and ΔfHm∘ [(C2H10N2)CdCl4, s] = −(960.99 ± 1.36) kJ · mol−1, respectively.