THE STRUCTURE OF CL- SOLUTIONS IN ETHYLENE-GLYCOL STUDIED BY NEUTRON-DIFFRACTION

The method of isotopic substitution in neutron diffraction is applied to study thc coordination envimnment of Cl- in a 0.999(3) molal solution of NaCl in fully deuterated ethylene glycol (EG). It is shown that the FG molecules act as monodentate ligands to give a Cl(EG)4- complcx that comprism Cl-... D-O bydrogen bonds which are approximately linear and of length 2.14.(3) angstrom. The results are compared with those obtained for the Cl- coordination complex in aqueous and methanolic solution. It is found that there is a reduction from congruent-to 6 to congruent-to 4 in the number of ligands binding to Cl- on changing the solvent from water to EG and that, for all three solvents, the Cl-...D-O hydrogen bond is typically linear. The effect of a small hydrogen imbalance between the solutions used for isotopic substitution experiments is briefly considered.