Crystal structures of complexes between alkali-metal salts and cyclic polyethers. Part 10. Complex formed between 6,7,9,10,12,13,15,16,23,24,26,27,29,30,32,33-hexadecahydrodibenzo[b,q][1,4,7,10,13,16,19,22,25,28]decaoxacyclotriacontin (dibenzo-30-crown-10) and two molecules of sodium isothiocyanate

Abstract

The crystal structure of the complex formed between two ion pairs of sodium isothiocyanate and one molecule of dibenzo-30-crown-10 has been determined from X-ray diffraction measurements. In a monoclinic unit cell, having a= 25.167(8), b= 8.921(3), c= 17.293(6)Å, β= 17.88(2)°, and space group C2/c, there are four neutral discrete molecules of complex and four of water of crystallisation. Full-matrix anisotropic refinement on 2 504 observed reflections was complete at R= 0.045. Each ligand complexes with two sodium cations, and each cation is also co-ordinated to one isothiocyanate anion through the nitrogen atom (Na–N 2.363 Å). The two halves of the complex are related by a crystallographic two-fold rotation axis which passes through two oxygen atoms, O(11) and O(28), of the ligand. These atoms bridge the cations (Na–O 2.531 and 2.585 Å respectively) which are 3.94 Å apart. The nitrogen atom and bridging atom O(28) form the apices of an approximately pentagonal-bipyramidal arrangement round the sodium ion (Na–O, unshared: 2.413, 2.493, 2.398, and 2.453 Å).