The Structure of Zinc Chloride Complexes in Aqueous Solution

The structure of zinc chloride complexes with different ratios of chloride to zinc, formed in concentrated ZnCl2 aqueous solutions, were determined f rom large-angle X-ray scattering using concentrations of the chloride complexes estimated by complementary Raman spectroscopic measurements. The highest chloro complex, [ZnCl4]~, is tetrahedral with a Zn-Cl bond length of 2.294(4) Ä. The trichloro complex, [ZnCl3]~, which coordinates one water molecule, is pyramidal with the Cl-Zn-Cl angle 111°. The Zn-Cl and the Z n H 2 0 bonds are 2.282(4) and 1.9 A, respectively. The two lower complexes, [ZnCl2] and [ZnCl] + , cannot be separated by Raman spectra.oThe average Zn-Cl distance in these complexes is 2.24 Ä, and the average Z n H 2 Ö distance is 1.9 A. In [ Z n ( H 2 0 ) 6 ] 2 + the Z n H 2 0 distance is 2.15 Ä.