| Abstract: | Hydrates of Cerium(III) Chloride The thermal dehydration of CeCl3 · 7 H2O to CeCl3 gives four definite intermediates: CeCl3 · 6 H2O, CeCl3 · 3 H2O, CeCl3 · 2 H2O, CeCl3 · H2O. In the hexahydrate monomeric CeCl2(H2O)6]+ units exist. A structure analysis of CeCl3 · 3 H2O gave an orthorhombic unit cell (S.G. Pnma; Z = 4) with a = 1 242.7(4) pm; b = 881.8(8) pm, c = 693.4(5) pm. The structure consists of CeCl4/2Cl(H2O)3] chains, where two Ce3+ ions are connected via two chloride ions, forming bent chains in the 010] direction. The trihydrates LnCl3 · 3 H2O (Ln = Pr? Tb) are isotypic, also one modification of LaCl3 · 3 H2O. The structures of the di- and mono-hydrate are not yet known. Molar volumina and solution enthalpies in water vary linearly with the number of H2O molecules per formula unit. |
