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

Abstract

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 P. 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. 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.