Mixed azide and carboxylate bridged trinuclear Mn(ii) and Co(ii) motifs in coordination ladders: structures and magnetism

Abstract

Two isomorphous Mn(II) and Co(II) coordination polymers with an azide and zwitterionic dicarboxylate ligand as coligands were synthesized and structurally characterized, and their magnetic properties were studied. They are formulated as [M₃(L)₂(N₃)₆(H₂O)₂]·2H₂O (M = Mn (1), Co (2), L = 1,2-bis(4-carboxylatopyridinium-1-methylene)benzene). The compounds contain anionic linear [Mn₃(N₃)₆(COO)₄(H₂O)₂]⁴⁻ units built from the simultaneous bridges of a syn–syn carboxylate and two end-on azides. The anionic trinuclear units are linked into ladder-like coordination polymers by the cationic bis(pyridinium) tether of the organic ligand. Analyses of the temperature- and field-dependent magnetic data of the compounds revealed that the mixed [(COO)(EO–N₃)₂] triple bridges transmit antiferromagnetic and ferromagnetic coupling in 1 and 2, respectively.