New Organically Templated Ln(III)−Cu(I) Heteronuclear Sulfite Bromides

Two novel organically templated 3d−4f mixed metal sulfites, namely, [H2pip][Ln4Cu4(SO3)8Br2(H2O)6] (Ln = Eu, 1; Gd, 2; pip = piperazine) have been synthesized and structurally characterized. Compounds 1 and 2 are isostructural and feature a 2D inorganic anion layer of [Ln4Cu4(SO3)8Br2(H2O)6]2−. Among two unique lanthanide(III) ions in the asymmetric unit, one is eight coordinated by seven oxygen atoms from six sulfite groups (five of them in unidentate fashion and one in bidentate chelating fashion) and an aqua ligand; the other one is eight-coordinated by six oxygen atoms from five sulfite groups (four of them in unidentate fashion and one in bidentate chelating fashion) and two aqua ligands. Cu(1) is four coordinated by two S and one O from three SO32− anions, as well as a Br anion, and Cu(2) is three coordinated by one S and one O atom from two SO32− anions, as well as a Br anion. The Ln(III) ions and Cu(I) ions are interconnected by sulfite anions and Br anions to form a layered structure. The piperazine molecules are located at the interlayer spaces. Magnetic properties for both compounds were also studied.