Manganese(ii) coordination polymers with mixed azide and pyridylbenzoate N-oxide ligands: structures and magnetism

Two novel Mn(II) coordination polymers with azide and 4-(4-pyridyl)benzoic acid N-oxide (4,4-Hopybz) were synthesized and structurally and magnetically characterized. They are formulated as {[Mn2(4,4-opybz)2(N3)2(H2O)2]·H2O}n (1) and {[Mn4(4,4-opybz)5(N3)(H2O)8](N3)2·2H2O}n (2). Compound 1 contains 2D coordination layers in which the infinite Mn(II) chains with alternating (μ-EO-N3)2(μ-COO) (EO = end-on) and (μ-COO)(μ-O) bridges are interlinked by the backbones of the organic ligands. Compound 2 is a 3D metal–organic framework in which the unique linear tetranuclear clusters with (μ-EO-N3)(μ-COO) and (μ-COO)(μ-O) bridges are cross-linked by organic backbones, and it represents a new example of the rare 8-connected self-catenated 3D net with the point symbol 416·612. Magnetic analyses on the compounds have been performed in the classical-spin approximation, revealing that all the above-mentioned mixed bridging motifs induce weak antiferromagnetic interactions between Mn(II) ions.