Disordered Crystal Structure of Bis[(2.2.2-Cryptand)Sodium] Bis[Aqua(Isothiocyanato)(μ-Isothiocyanato)Sodium] 2[Na(2.2.2-Crypt)] + · [Na 2 (NCS) 2 (μ-NCS) 2 (H 2 O) 2 ] 2–

Abstract

Crystals of bis[(2.2.2-cryptand)sodium] bis[aqua(isothiocyanato)(μ-isothiocyanato)sodium]: 2[Na(C18H36N2O6)]+ · [Na2(NCS)2(μ-NCS)2(H2O)2]2– (I) were synthesized and studied by X-ray diffraction analysis. The disordered structure of I (a = 12.715 A, b = 10.458 A, c = 21.767 A, β = 102.56°, space group P21/n) was solved by the direct method and refined by the full-matrix least-squares method in anisotropic approximation to R = 0.058 from 3896 independent reflections (CAD4 automated diffractometer, λMoKα). The crystal consists of two complex ions [I1]+ and [I2]2– (molar ratio 2 : 1). The Na+ cation of the host–guest cation I1 is coordinated by all eight heteroatoms (6O + 2N) of the cryptand ligand. The coordination polyhedron of this Na+ cation is a distorted cube. The atoms of two groups (CH2–CH2 and CH2–O–CH2–CH2) in the cryptand ligand are disordered over two positions. The independent cation Na+ of the centrosymmetric binuclear complex anion I2 is coordinated by one bifurcated O atom of the disordered water molecule and by three N atoms of the SCN– ligands (including two bridging ligands). The coordination polyhedron of this Na+ caiotn is a distorted tetrahedron. The complex ions in the crystal structure of I are united by hydrogen bonds.