Lanthanide Complexes Based on 1,3-Dimethylimidazolium-4-Carboxylate: Syntheses and Structures

The reactions of the norzoanemonine zwitterion, 1,3-dimethylimidazolium-4-carboxylate (L), with praseodymium(III), samarium(III), and europium(III) chlorides afford crystals of two types: the isostructural binuclear complexes [Ln2(μ-C6H8N2O2)4(HOCH3)4(H2O)4]Cl6 (Ln = Pr(III) (I) and Eu(III) (II)) and the dimeric samarium complex [Sm2(μ-C6H8N2O2)4(C6H8N2O2)2(H2O)5(OCH3)]Cl5 (III), which are characterized by X-ray diffraction analysis and IR spectroscopy. In complexes I–III (CIF files CCDC nos. 1912829 (I), 1912830 (II), 1912831 (III), the metal atoms are bound by four bridging L molecules without forming the metal–metal bond (the M···M distances are 4.595 Å in I, 4.4637 Å in II, and 4.584 Å in III).