Three 3d–4f heterometallic complexes constructed from oxalic acid and benzimidazole-5,6-dicarboxylic acid

Abstract

Three 3d–4f heterometallic complexes, namely, [Co₃Ln₂(L)₄(C₂O₄)₂(H₂O)₂·6H₂O]_n (Ln = Pr (1), Nd (2), Sm (3); H₂L = benzimidazole-5,6-dicarboxylic acid, H₂C₂O₄ = oxalic acid), have been synthesized hydrothermally and characterized by single crystal X-ray diffraction study, IR, TGA and elemental analysis. The three complexes are isostructural; in their structures, the Co(II) centers are connected into a linear Co₃ cluster by the C₂O₄²⁻ anions, the Ln(III) centers are connected into one-dimensional (1D) {Ln–O–C}_n rod-like chains by the carboxyl groups of L²⁻ anions, the linear Co₃ clusters and {Ln–O–C}_n rod-like chains are further connected by the L²⁻ anions, and finally construct three 3D frameworks, which contain 1D channels along the b direction occupied by (H₂O)₈ clusters. In addition, magnetic studies of the three complexes all reveal antiferromagnetic behaviors.