Mn(II)2Gd(III)3 Phosphonate as a Molecular Refrigerant

3d-Gd phosphonate clusters are attractive for their potential applications as magnetic coolers. A new pentanuclear cluster [Mn(II)2Gd(III)3(OH)(dtbmfPO3)2(tBuCO2)8(HO2CtBu)(H2O)2]·HO2CtBu·CH3CN (1) (dtbmfPO3H2 = (2,7-di-tert-butyl-9-methyl-9H-fluoren-9-yl)phosphonic acid) has been synthesised and characterised. The cluster has a planar structure in which the trinuclear {MnGd2(OH)} and dinuclear {MnGdO2} units are joined together by two phosphonate groups. The magnetic studies reveal that 1 shows antiferromagnetic interactions and a large magnetocaloric effect (ΔS = 20.9 J kg–1 K–1 at ΔH = 7 T).

An azide-bridged copper(II) complex: poly[piperazine-1,4-dium [tetra-μ3-azido-κ12N1:N1:N1-hexa-μ2-azido-κ12N1:N1-di-μ2-azido-κ4N1:N3-pentacopper(II)] tetrahydrate]

A new CuII–azide complex, {(C4H12N2)[Cu5(N3)12]·4H2O}n, has been synthesized by the reaction of piperazine, Cu(OAc)2·2H2O (OAc is acetate) and NaN3. In the structure, μ2-1,1- and μ3-1,1,1-azide anions bridge five CuIIcations to form a linear pentanuclear cluster unit, which is further linked by μ2-1,1- and μ2-1,3-azide anions to form a two-dimensional condensed [Cu5(N3)12]nlayer. The diprotonated piperazine and the solvent water molecules are hydrogen bonded to the coordination layers to form a three-dimensional supramolecular network.