The Crystal and Molecular Structure of the Hydrated Light Lanthanoid(III) Chloroacetates, [{M(ClCH2CO2)3}3(H2O)5]n, (M=La, Pr, Nd, and Eu)

The crystal and molecular structures of the hydrated lanthanum(III), neodymium(III), and europium(III) chloroacetates indicated in the title were determined by the single-crystal X-ray diffraction method; these three salts as well as the praseodymium(III) salt are apparently isomorphous. By the same synthetic technique, gadolinium(III) or heavier lanthanoid(III) did not give the isomorphous salts. Their crystals are monoclinic with the space group of P21⁄c, and the cell constants of the neodymium(III) salt, for example, are, a=14.805(4), b=18.765(4), c=14.403(5) Å, β=95.13(3)°. There are crystallographically independent three kinds of nine-coordinated metal atoms: Nd(1), Nd(2), and Nd(3). Among them, Nd(1) and Nd(2) are best approximated as being in a tricapped trigonal prism geometry. The Nd(3) is best regarded as being in a monocapped square-antiprism geometry, although one more additional oxygen atom, O(35), approaches one side face. In the lanthanum(III) complex, O(35) is thought to be ligated to La(3), while in the europium(III) complex O(35) is perfectly removed from Eu(III), being accompanied by a change in the coordination geometry of the ligand. In the crystal, the metal atoms are bridged by carboxylato ligands, forming polymeric chains approximately along [−110] or [110] axis. There are no carboxylato bridges between respective chains, although there are some hydrogen-bondings linking them with each other.