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

The rare earth complex,RE(H3O)83+,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.