Crystal structures of complexes between alkali-metal salts and cyclic polyethers. Part V. The 1 : 2 complex formed between potassium iodide and 2,3,5,6,8,9,11,12-octahydro-1,4,7,10,13-benzopentaoxacyclopentadecin (benzo-15-crown-5)

摘要: Potassium iodide forms a 1 : 2 complex with the cyclic polyether ‘benzo-15-crown-5’. The crystals are tetragonal a=b= 17·84(1), c= 9·750(6)A, Z= 4, space group P4/n. crystal structure has been determined by heavy-atom method and refined full-matrix least-squares to final R of 0·09 on 1603 diffractometer data. cation crystallographic symmetry , potassium being ‘sandwiched’ between two centro-symmetrically related ligand molecules. In each these five ether-oxygen atoms approximately coplanar, lying 1·67 A away from this plane, so that ten-co-ordination is an irregular pentagonal antiprism. K–O distances range 2·777(7) 2·955(8)A. Iodide ions occupy sets positions 4 or arrangement cations anions resembles caesium chloride structure; there no interaction metal.