Synthesis, structures and magnetocaloric properties of two dinuclear GdIII clusters derived from monocarboxylate ligands

Two dinuclear Gd-III clusters, namely [Gd-2(piv)(6)(phen)(2)] (1) and {[Gd-2(2-TCA)(6)(phen)(2)]center dot 2H(2)O} (2) (Hpiv = pivalic acid, 2-TCA = Thiophene-2-carboxylic acid and phen = 1,10-phenanthroline), have been synthesized under hydrothermal conditions. Complex 1 features dinuclear structure with two syn-syn-mu(2)-eta(1):eta(1) carboxylates bridging, while 2 exhibits dinuclear structure bridged by four carboxylates with syn-syn-mu(2)-eta(1):eta(1) and syn-syn-mu(2)-eta(1):eta(2) modes. Magnetic studies indicate that weak antiferromagnetic interactions between adjacent Gd-III ions exist in 1 and 2. They exhibit relatively large magnetocaloric effects with -Delta S-m(Max) = 19.1 J kg(-1) K-1 and 21.8 J kg(-1) K-1 for Delta H = 70 kOe, respectively, influenced by relatively high magnetic density and weak magnetic interaction. (C) 2016 Elsevier Ltd. All rights reserved.