Crystal structure of [Ni(OH₂)₆]Cl₂·(18-crown-6)₂·2H₂O

The crystal structure of the title compound, hexa-aqua-nickel(II) dichloride-1,4,7,10,13,16-hexa-oxa-cyclo-octa-deca-ne-water (1/2/2), [Ni(H₂O)₆]Cl₂·2C₁₂H₂₄O₆·2H₂O, is reported. The asymmetric unit contains half of the Ni(OH₂)₆ moiety with a formula of C₁₂H₃₂ClNi_0.50O₁₀ at 105 K and triclinic (P1) symmetry. The [Ni(OH₂)₆]²⁺ cation has close to ideal octa-hedral geometry with O-Ni-O bond angles that are within 3° of idealized values. The supra-molecular structure includes hydrogen bonding between the water ligands, 18-crown-6 mol-ecules, Cl^- anions, and co-crystallized water solvent. Two crown ether mol-ecules flank the [Ni(OH₂)₆]²⁺ mol-ecule at the axial positions in a sandwich-like structure. The relatively symmetric hydrogen-bonding network is enabled by small Cl^- counter-ions and likely influences the more idealized octa-hedral geometry of [Ni(OH₂)₆]²⁺.