Dipotassium hexa­aqua­nickel(II) bis­[hexa­fluoridozirconate(IV)]

Single crystals of the title compound, K2[Ni(H2O)6][ZrF6]2, were grown by slow evaporation of a 40% aqueous HF solution in which a stoichiometric mixture of NiCl2·6H2O, ZrF4 and KCl was dissolved. The monoclinic structure is isotypic with its K2Cu, K2Zn, Cs2Zn and Cs2Cu analogues. The structure is built up from isolated, slightly elongated octa­hedral [Ni(H2O)6]2+ complex cations (symmetry ) and dimeric [Zr2F12]4− complex anions (symmetry ) that are also isolated from each other. The [Zr2F12]4− anion results from the association of two distorted penta­gonal–bipyramidal [ZrF7] coordination polyhedra by sharing an equatorial edge passing through an inversion center of the unit cell. Both isolated [Ni(H2O)6]2+ and [Zr2F12]4− complex ions are situated in planes parallel to (010). They are connected by the eight-coordinated K+ ions into a three-dimensional structure. An intricate O—H⋯F hydrogen-bonding network consolidates the structure