The method of isotopic substitution in neutron diffraction is applied to study the coordination environment of the Ni2+ ion in a 0.956 m solution of Ni(CF3SO3)2 in fully deuterated ethylene glycol (EG). It is shown that EG molecules do not act as monodentate ligands but that Ni(EG)32+ tris-chelate complexes are formed. There is no evidence of inner-sphere complexing by the CF3SO3− anion, but the data are consistent with a spatially well defined hydrogen bond between EG ligands in the first and second coordination shells of the cation. If this bond is assumed to be linear, then it is of length ~1.8 (1) Å. The number of second-shell EG molecules that participate in this hydrogen-bond process is estimated at six. Furthermore, there is evidence for weak ordering of the Ni2+ correlations on a length scale of 10 ≲ r (Å) ≲ 16. The stability of the Ni(EG)32+ complex is briefly discussed.
ASJC Scopus subject areas
- Colloid and Surface Chemistry