On the Ni(II)/Ln(III) dinuclear complexes based on bicompartmental Schiff base type ligand with bromido co-ligands: structural comparison with the analogous chlorido complexes

Three new heterodinuclear lanthanide complexes with bromido co-ligands Ni(o-van-en)CeBr2(MeOH)(H2O)2Br·H2O (1), Ni(o-van-en)GdBr(H2O)3Br2·EtOH (2), and Ni(o-van-en)DyBr(H2O)3Br2·EtOH (3) (H2(o-van-en) is a Schiff base formed by the condensation of o-vanillin and ethylenediamine in 2 : 1 ratio) were synthesized in the single crystal form using diffusion methods and characterized by CHN analyses and IR spectroscopy. The structural characteristics of bromido complexes differ from those of analogous chlorido complexes, as the former exhibit an ionic crystal structure rather than a molecular one. The bromido complexes consist of Ni(II)/Ln(III) dinuclear complex cations with two (1) or one (2,3) bromido co-ligands, and additional methanol (1) and aqua (2, 3) co-ligands, respectively. The unit-cell contents are completed by water (1) and ethanol (2, 3) solvate molecules. The detailed structural comparison of the analogous complexes based on bromido and chlorido co-ligands is given. The thermal analysis of 3 affirmed its low thermal stability.