4,7,13,16,21,24-Hexaoxa-1,10-diazoniabicyclo[8.8.8]-hexacosane tetra(nitrato)zinc(II): Synthesis and crystal structure

A new complex salt 4,7,13,16,21,24-hexaoxa-1,10-diazoniabicyclo[8.8.8]-hexacosane tetra(nitrato) zinc(II), [H-2(Crypt-222)][Zn(NO3)(4)](2-), is synthesized and studied by X-ray diffraction analysis: space group P1, a = 10.556 angstrom, b = 11.089 angstrom, c = 14.536 angstrom, alpha = 104.63 degrees, beta = 109.23 degrees, gamma = 99.22 degrees, Z = 2. The structure is solved by a direct method and refined by the full- matrix least-squares method in the anisotropic approximation to R = 0.031 for 3897 independent reflections (CAD-4 automated diffractometer, lambda MoK alpha radiation). The structural units of the crystal are the [Zn(NO3)(4)](2-) complex anion and somewhat disordered 2.2.2-cryptand dication (with two protonated nitrogen atoms). The Zn2+ cation forms four strong coordination bonds with the O atoms of four NO3- ligands and four weak (secondary) bonds with the second O atoms of these ligands. While ignoring the latter, the Zn2+ cation has a strongly distorted tetrahedral configuration. The [H-2(Crypt-222)](2+) dication contains trifurcate hydrogen bonds N-H(center dot center dot center dot O)(3).