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 {[Mn-2(4,4-opybz)(2)(N-3)(2)(H2O)(2)]center dot H2O}(n) (1) and {[Mn-4(4,4-opybz)(5)(N-3)(H2O)(8)](N-3) (2)center dot 2H(2)O}(n) (2). Compound 1 contains 2D coordination layers in which the infinite Mn(II) chains with alternating (mu-EO-N-3)(2)(mu-COO) (EO = end-on) and (mu-COO)(mu-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 (mu-EO-N-3)(mu-COO) and (mu-COO)(mu-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 4(16).6(12). 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.