Effect of lanthanide contraction and rigid ligand on the structure of salen-type lanthanide complexes

Abstract

Three types of phenolate oxygen-bridged N,N′-bis(2-oxy-3-methoxybenzylidene)-1,2-diaminophenylene 3d–4f heteronuclear and 4f tetranuclear complexes, namely, [(LZnCl)PrCl2(CH3OH)2]2 (1), [(LZnCl)LnCl(OAc)(CH3OH)] (Ln = Tb (2) and Dy (3)) and [{(LLu2)(OAc)2(H2O)(OH)}2(ZnCl4)]·2H2O (4) are obtained by reactions of H2L (H2L = N,N′-bis(2-oxy-3-methoxybenzylidene)-1,2-phenylenediamine), LnCl3·6H2O (Ln = Pr, Tb, Dy and Lu) and Zn(OAc)2·2H2O in CH3OH/CH2Cl2. X-Ray crystallographic analysis reveals that complex 4 possesses a novel defect-dicubane core, where four Lu3+ ions are inserted into the two sets of N2O2 and O2O2 cavities among the two tail-to-tail ligands. The structural investigations unambiguously testify that the lanthanide contraction and the rigid ligand cooperatively affect the formation of complexes 1–4, where Ln3+ ions with large, medium and small radius are composed in three different structures. The fluorescent spectrum of complex 2 exhibits the characteristic metal-centred fluorescence of Tb3+ ions.