A NEUTRON-DIFFRACTION STUDY ON THE STRUCTURE OF CL- SOLUTIONS IN HYDROGEN-BONDED MOLECULAR-SOLVENTS

The method of isotopic substitution in time-of-flight neutron diffract ion is applied to measure the coordination environment of Cl- in a 0.9 99(2) molal solution of NaCl in fully deuterated glycerol. It is shown that the glycerol molecules act as monodentate ligands to give a Cl(g lycerol)3- complex that comprises Cl-...D-0 hydrogen bonds, which are approximately linear and of length 2.17(3) angstrom. The results are c ompared with those obtained for the solvation of Cl- in solutions of i ts salts in water, methanol and ethylene glycol (EG). A reduction from approximately six (water) to four (methanol and EG) to three (glycero l) is found for the Cl-solvation number as the solvent is changed and, for all four solvents, the Cl-...D-O hydrogen bond is typically linea r.