Crystals of a new double complex salt KCo(NH3)6Cr2(C3H2O4)4(OH)2Cl·5.33H2O (1) are prepared for first time by the isothermal evaporation of an aqueous solution containing hexammine cobalt(III) chloride, chromium(III) nitrate, and potassium malonate. The new compound crystallizes in the monoclinic crystal system, C2/c space group, a = 13.6657(3) Å, b = 15.2499(3) Å, c = 15.8264(7) Å, β = 114.285(3)°, V = 3006.37(2) Å3. The crystal structure of the new compound contains a relatively rare Cr2(C2H3O4)4(OH)2]4– dinuclear anion.
Kireev et al. (Sun,) studied this question.