Synthesis, crystal structures and magnetic behaviour of dimeric and tetrameric gadolinium carboxylates with trichloroacetic acid

The novel gadolinium(III) containing compounds (CH3NH3)2[Gd2(CCl3COO)6(H2O)6](CCl3COO)2.2CCl3COOH (1) and (NH3CH3)2[Gd4(OH)4(CCl3COO)10(H2O)6].2H2O (2) were synthesized and structurally characterized by X-ray crystallography. In the crystal structure of 1 the gadolinium ions are bridged by carboxylate groups to dimers with a Gd3+ -Gd3+ distance of 420.2(3) pm. The compound crystallizes in the triclinic space group P1. In the crystal structure of the Gd3+ ions are bridged by hydroxide ions and carboxylate groups to tetramers with Gd3+ -Gd3+ distances between 380.3(1) and 388.0(1) pm. The compound crystallizes in the triclinic space group P1. The magnetic behaviour of these two compounds as well as of Gd2(CCl3COO)6(bipy)2(H2O)2.4bipy (3) (bipy = 2,2'-bipyridyl) was investigated in the temperature range 1.77-300 K. The magnetic data for these compounds indicate weak antiferromagnetic interactions.