Synthesis and crystal structure of octaaquaerbium(III) 4,7,13,16,21,24-Hexaoxa-1,10-diazoniabicyclo[8.8.8]hexacosane pentabromide hydrate

A new complex salt Er(H₂O)₈]³⁺·H₂(Crypt-222)]²⁺·5Br^?·1.5H₂O(I) is synthesized, and its crystal structure is studied by single-crystal X-ray diffraction analysis (space group P2₁, a = 8.315 Å, b = 32.000 Å, c = 8.383 Å, β = 120.03°, Z = 2; direct method, anisotropic full-matrix least-squares approximation, R = 0.050 for 3755 independent reflections; CAD4 automated diffractometer, λMoK _α radiation). The structural units of crystal I are complex cations Er(H₂O)₈]³⁺, disordered dications of the 2.2.2-cryptand (with two protonated nitrogen atoms), Br^? anions, and water molecules. The coordination polyhedron of the Er³⁺ cation is a tetragonal antiprism with the oxygen atoms of eight water molecules at its vertices. The disordered H₂(Crypt-222)]²⁺ dication contains trifurcate hydrogen bonds N⁺-H(?O)₃.