Microscopic structure of nickel(II) co-ordination shell in NiCl2-methanol solution:: neutron diffraction and ab initio studies

Neutron diffraction measurements were carried out on similar to 1.4 molal solutions of NiCl2 in methanol under ambient conditions. First-, second- and high-order difference methods with isotopic substitution on nickel, chlorine and hydroxy hydrogen (H-O) were applied in conjunction with ab initio calculations of Ni2+-methanol complex to derive Ni-O, Ni-H-O, Ni-Cl, Ni-C and Ni-H(methyl) pair radial distribution functions, RDFs. Analyses of these RDFs demonstrates that Ni2+ is co-ordinated octahedrally by five methanol molecules and one chloride anion with the nearest-neighbour Ni-O, Ni-Cl and Ni-H-O distances of 2.057(1), 2.348(2) and 2.619(6) Angstrom, respectively. The results also reveal a preferential triangular orientation of the methanol molecules surrounding Ni2+ in its co-ordination shell.