4,7,13,16,21,24-Hexaoxa-1,10-diazoniabicyclo[8.8.8]hexacosane Bis[dibromodichloroiron(III)]: Synthesis and Crystal Structure

Abstract

A novel complex salt, namely, 4,7,13,16,21,24-hexaoxa-1,10-diazoniabicyclo[8.8.8]hexacosane bis[dibromodichloroiron(III)] [H₂(Crypt-222)]²⁺[FeBr₂Cl₂] ⁻₂ (I), was synthesized and structurally characterized by X-ray diffraction analysis (monoclinic crystal system, a = 13.550 Å, b = 11.018 Å, c = 12.813 Å, β = 117.52°, space group C2, Z = 2). The structure was solved by the direct method and refined by the full-matrix least-squares method in the anisotropic approximation to R = 0.089 from 2593 independent reflections (CAD4 automated diffractometer, λMoKα radiation). In the crystal structure I, four bifurcate positions of Br and Cl in the tetrahedral anion [FeBr₂Cl₂]⁻ are a randomly disordered mixture of these atoms. The dication of 2.2.2-cryptand (with two protonated N atoms) in the crystallographic axis 2 contains trifurcate N⁺-H (⋯O)₃ hydrogen bonds.