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

The novel gadolinium(III) containing compounds (CH3NH3)(2)[Gd-2(CCl3COO)(6)(H2O)(6)](CCl3COO)(2) center dot 2CCl3COOH (1) and (NH3CH3)(2)[Gd-4(OH)(4)(CCl3COO)(10)(H2O)(6)] center dot 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 P $$(1) over bar . In the crystal structure of 2 the Gd3+ ions are bridged by hydroxide ions and carboxylate groups to tetramers with Gd3+ - Gd3+ distances between 380.3(1) and 388.0(1) pm. The compound crystallizes in the triclinic space group P $$(1) over bar . The magnetic behaviour of these two compounds as well as of Gd-2(CCl3COO)(6)(bipy)(2)(H2O)(2) center dot 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.