The coordination (hydration) of rare earth ions in aqueous chloride solutions from x ray diffraction. I.TbCl3,DyCl3, ErCl3,TmCl3,and LuCl3

Abstract

The rare earth complex,[RE(H₃O)₈]³⁺,has been identified in concentrated (3.2−3.6 m) aqueous TbCl₃,DyCl₃,ErCl₃,TmCl₃, and LuCl₃ solutions from x ray diffraction measurements. The inner sphere water coordination of rare earth ion was obtained from quantitative resolution of the radial distribution functions. In each solution the rare earth ion has eight water nearest neighbors with the average RE³−H₂O distances being 2.409, 2.396, 2.369, 2.358, and 2.338Å for TbCl₃,DyCl₃, ErCl₃, TmCl₃, and LuCl₃,respectively. The average RE³⁺. . . Cl⁻ ion pair distances are near 4.8Å.