Thulium(III) trifluoroacetates Tm(CF3COO)3 · 3H2O and Tm2(CF3COO)6 · 2CF3COOH · 3H2O: Synthesis and crystal structure

Abstract

Thulium trifluoroacetate compounds have been synthesized, Tm(CF3COO)3 · 3H2O (I) and Tm2(CF3COO)6 · 2CF3COOH · 3H2O (II). The structure of I has been refined by the Rietveld method on the basis of the structural data for Cd(CF3COO)3 · 3H2O. The structure of II has been solved in a single-crystal X-ray diffraction study. Compound I has been studied by thermal analysis. Crystals of I and II are monoclinic: for Ia = 9.062(2) A, b = 18.678(3) A, c = 9.687(2) A, β = 113.93(1)°, Z = 2, space group P21/c, R1 = 0.062; for IIa = 8.560(4) A, b = 19.866(5) A, c = 20.813(7) A, β = 101.69(4)°, Z = 8, space group C2/c, R1 = 0.0392. In the molecular structure of I, thulium atoms are bonded in pairs through four bridging trifluoroacetate anions to form dimers. The coordination polyhedron of the thulium atom also includes the three O atoms of the water molecules and the O atom of the monodentate trifluoroacetate group; the coordination number of the thulium atom is eight. In the chain structure of II, there are two crystallographically independent thulium atoms with coordination numbers 8 and 9. The coordination polyhedra of the Tm(1) and Tm(2) atoms are a distorted monocapped tetragonal antiprism and a distorted tetragonal antiprism, respectively. The Tm-O bond lengths are in the range 2.28(1)–2.85(2) A. The thulium atoms are bound into chains through carboxylate groups. These chains are linked into layers through hydrogen bonds.