BARIUM COPPER(II) OXOCARBON COMPOUNDS - SYNTHESIS, CRYSTAL-STRUCTURES AND THERMAL BEHAVIORS OF [BA(H2O)(5)][CU(C2O4)(2)(H2O)] AND [BA(C4O4)(0.5)(H2O)(2)](2)[CU(C4O4)(2)(H2O)(2)]

[Ba(H2O)(5)][Cu(C2O4)(2)(H2O)] and [Ba(C4O4)(0.5)(H2O)(2)](2)[Cu(C4O4)(2)(H2O)(2)] were obtained as single crystals in water. The structures were determined from X-ray diffraction data. [Ba(H2O)(5)][Cu(C2O4)(2)(H2O)]: triclinic, space group P (1) over bar, a=9.209(2), b=10.938(1), c=6.547(1) Angstrom, alpha=100.83(1), beta=99.65(2), gamma=85.45(2)degrees Z=2; [Ba(C4O4)(0.5)(H2O)(2)](2)[Cu(C4O4)(2)(H2O)(2)]: triclinic, space group P (1) over bar, a=7.752(1), b=10.445(2), c=7.420(1)Angstrom, alpha=99.24(1), beta=113.20(1), gamma=109.87(1)degrees, Z=1. They are made of cationic layers separated by anions [Cu(C2O4)(2)(H2O)](2-) and [Cu(C4O4)(2)(H2O)(2)](2-), respectively. Both compounds were submitted to thermal gravimetric and differential analyses in an oxygenated atmosphere, up to 950 degrees C. Final decomposition products were (i) BaCuO2 with small amounts of BaCO3 and CuO for [Ba(H2O)(5)][Cu(C2O4)(2)(H2O)], and (ii) an equimolecular mixture of BaCuO2 and BaCO3 for [Ba(C4O4)(0.5)(H2O)(2)](2)[Cu(C4O4)(2)(H2O)(2)].