The structure and magnetic properties of a dodecanuclear iron(III) wheel are reported, featuring a bridging zwitterionic ligand.

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An X-ray diffraction study of the title complex has been carried out. The crystal is orthorhombic, with the space group P212121; Z=4, a=10.021(3), b=13.562(4), c=7.298(3) Å. Block-diagonal least-squares refinements have led to the final R value of 0.035. The structure is very similar to that of dichloro(4-hydroxy-l-proline)cadmium(II), which has a one-dimensional polymer bridged by chlorine atoms and a carboxyl group like an infinite folding screen. The thermal behavior is, however, different from that of dichloro(4-hydroxy-l-proline)cadmium(II). The difference is likely to be due to a difference of the crystal structure, whether it contains intermolecular hydrogen bonds or not.

Water is the glue in bridging two [GdNi3] heterometallic fragments to form the new molecular cluster [Et4N][Gd2Ni6(val)12(MeCN)6(H2O)3][Gd(NO3)5](ClO4)5 (1, val= valine anion, see figure), otherwise cemented by amino acid ligands. The shape of the complex cation of 1 resembles an ancient goblet, and its structure holds weak magnetic exchange pathways, as confirmed theoretically and experimentally; this confers the cluster ideal conditions to exhibit good magnetocaloric properties.