Reduced zirconium halide clusters in aqueous solution

Reduced hexazirconium halide cluster compounds have good solubility and stability in strongly acidic and/or halide-rich aqueous solutions. Cyclic voltammetric (CV) measurements in aqueous media established that (Zr6BCl12)(H2O)6]2+/+ and (Zr6BBr12)(H2O)6]2+/+ exhibited positive half-wave potentials (E1/2 = 0.059V and 0.160 V, respectively) vs the SHE, indicating that these clusters are only modestly reducing. Several new crystalline cluster compounds have been isolated from cold 12 M HCl solutions; the structures of each contain extended hydrogen-bonding water networks. Crystallographic data for these compounds are reported as follows: Rb0.44(H3O)4.56](Zr6BCl12)Cl6].19.44H2O (3), cubic, Im3m, a = 13.8962(3) A, Z = 2; (H3O)5(Zr6BeCl12)Cl6].19H2O (4), cubic, Im3m, a = 13.8956(4) A, Z = 2; (H3O)5(Zr6MnCl12)Cl6].19H2O (5), cubic, Im3m, a = 14.029(3) A, Z = 2; (H3O)4(Zr6BCl12)Cl6].12.97H2O (6), tetragonal, P4(2)/mnm, a = 11.5373(2) A, c = 15.7169(4) A, Z = 2; (H3O)4(Zr6BCl2)Br6].13.13H2O (7), tetragonal, P4(2)/mnm, a = 11.7288(6) A, c = 15.931(1) A, Z = 2.