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

Abstract

A new complex salt 4,7,13,16,21,24-hexaoxa-1,10-diazoniabicyclo[8.8.8]-hexacosane tetra(nitrato)zinc(II), [H2(Crypt-222)][Zn(NO3)4]2−, is synthesized and studied by X-ray diffraction analysis: space group \(P\bar 1\), a = 10.556 A, b = 11.089 A, c = 14.536 A, α = 104.63°, β = 109.23°, γ = 99.22°, 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, λMoKα 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 [H2(Crypt-222)]2+ dication contains trifurcate hydrogen bonds N-H(…O)3.