BARIUM COPPER(II) OXOCARBON COMPOUNDS - SYNTHESIS, CRYSTAL-STRUCTURESAND 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)d egrees 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)Angst rom, 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 sub mitted to thermal gravimetric and differential analyses in an oxygenat ed atmosphere, up to 950 degrees C. Final decomposition products were (i) BaCuO2 with small amounts of BaCO3 and CuO for [Ba(H2O)(5)][Cu(C2O 4)(2)(H2O)], and (ii) an equimolecular mixture of BaCuO2 and BaCO3 for [Ba(C4O4)(0.5)(H2O)(2)](2)[Cu(C4O4)(2)(H2O)(2)].