Disordered Crystal Structure of Bis[(2.2.2-Cryptand)Sodium] Bis[Aqua(Isothiocyanato)(#my#-Isothiocyanato)Sodium] 2[Na(2.2.2-Crypt)]~+(centre dot)[Na_2(NCS)_2(#mu#-NCS)_2(H_2O)_2]~(2-)

摘要

Crystals of bis[(2.2.2-cryptand)sodium] bis[aqua(isothiocyanato)(#my#-isothiocyanato)sodium]: 2[Na(C_(18)H_(36)N_2O_6)]~+(centre dot)[Na_2(NCS)_2(H_2O)_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, #beta# = 102.56 deg C, space group P2_1) 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, #lambda#MoK_#alpha#). The crystal consists of two complex ions [I~1]~+ and [I~2]~(2-) (molar ratio 2 : 1). The Na~+ cation of the host-guest cation I~1 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 (CH_2-CH_2 and CH_2-O-CH_2-CH_2) in the cryptand ligand are disordered over two positions. The independent cation Na~+ of the centrosymmetric binuclear complex anion I~2 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~+ cation is a distorted tetrahedron. The complex ions in the crystal structure of I are united byhydrogne bonds.