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

Abstract

Neutron diffraction measurements were carried out on ∽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) Å, respectively. The results also reveal a preferential triangular orientation of the methanol molecules surrounding Ni²⁺ in its co-ordination shell.