Heteronuclear M(II)–Ln(III) (M = Co, Mn; Ln = La, Pr, Sm, Gd, Dy and Er) coordination polymers: Synthesis, structures and magnetic properties

Thirteen novel 3d–4f heteronuclear coordination polymers based on the pyridine-2,6-dicarboxylic acid (H2pda) and imidazole ligands, HIm[(pda)3MLn(Im)2(H2O)2]·3H2O (Im = imidazole; M = Co, Ln = Pr (1), Gd (2), Dy (3), Er (4); M = Mn, Ln = Pr (5), Sm (6), Gd (7), Dy (8), Er (9)), HIm[(pda)3CoSm(Im)2(H2O)2]·2H2O (10), [(Im)4M(H2O)2][(pda)4La2(H2O)2]·2H2O (M = Co (11), Mn (12)), and [(pda)6Co3Pr2(H2O)6]·6H2O (13), have been prepared and structurally characterized. X-ray crystallographic analyses revealed that these complexes display four different types of structures. Complexes 1–9 are isostructural, and possess 1-D chain structures constructed by alternately arrayed nine-coordinated Ln(III) (Ln = Pr, Sm, Gd, Dy, Er) and six-coordinated M(II) (M = Mn, Co) ions. Complex 10 exhibits a unique one-dimensional structure, in which two independent chains are parallel viewed down the a-axis and anti-parallel viewed down the c-axis. Complexes 11 and 12 are isostructural and display 1-D homometallic chain structures. Complex 13 is a 3D framework fabricated through PrN3O6 and CoO6 polyhedrons as building blocks. The variable-temperature solid-state dc magnetic susceptibilities of complexes 2, 3, 4, 9 and 13 have been investigated. Antiferromagnetic exchange interactions were determined for these five complexes.

Treatment of pyridine-2,6-dicarboxylic acid/imidazole ligands with cobalt(II)/manganese(II) and lanthanide(III) salts under solvothermal conditions gives 13 structurally interesting 1-D and 3-D coordination polymers.Figure optionsDownload as PowerPoint slideResearch highlights
► Thirteen 3d-4f coordination polymers have been prepared and characterized. The complexes display four different types of structures.
► The magnetic properties of five complexes have been investigated.
► Antiferromagnetic interactions were determined for all these complexes.