Syntheses and crystal structures of (2.2.2-cryptand)potassium chloride and (2.2.2-cryptand)ammonium bromide(0.75)chloride(0.25) hydrates

Abstract

Two new complexes were synthesized, namely, 7: 2 (2.2.2-cryptand)potassium chloride and (2.2.2-cryptand)ammonium bromide(0.75)chloride(0.25) hydrates: [M(Crypt-222)]+ · Hal− · 3.5H2O, where M = K, Hal = Cl (I) and M = NH4, Hal = Br0.75Cl0.25 (II). The structures of two isomorphous crystals were studied by X-ray diffraction analysis. Trigonal (space group P\( \bar 3 \), Z = 2) structures I (a = 11.763 A, c = 11.262 A) and II (a = 11.945 A, c = 11.337 A) were solved by direct methods and refined by the full-matrix least-squares method in the anisotropic approximation to R = 0.057 (I) and 0.065 (II) for all 2626 (I) and 1654 (II) independent measured reflections (CAD-4 automated diffractometer, λMoKα). In structures I and II, the host-guest [M(Crypt-222)]+ complex cation lies on the threefold crystallographic axis and has the approximate D3 symmetry. In complex I, the coordination polyhedron of the K+ cation (CN = 8) is a bicapped trigonal prism somewhat distorted toward an antiprism. Complexes I and II contain H-bonded disordered cubes of the water molecules and the Cl− or Br− anions.