Ni–Cl bonding in concentrated Ni(II) aqueous solutions at high Cl− /Ni2+ ratios. An x-ray diffraction investigation

Abstract
Three concentrated Ni(II) solutions at Cl−/Ni2+ ratios of 4 and 5 have been examined by the x-ray diffraction technique. The Fourier transformed scattering data straightforth indicate inner complex formation between Ni2+ and Cl− ions. Octahedral Ni(H2O)6−nCl2−nn (n = 0, 1, 2) complexes are the species which are consistent with the distribution curves and the structure functions. The average numbers of bonded chloride ions per nickel atom have been determined in each solution and the reliability of the complexation numbers as well as of the structural parameters critically examined. The existence of an intermediate-range order in NiCl2 solutions is discussed within the frame of the current literature and the present findings.