A Unique Example of Structural Diversity Tuned by Apparently Innocent o-, m-, and p-Nitro Substituents of Benzoate in Their Complexes of Mn(II) with 4,4′-Bipyridine: 1D Ladder, 2D Sheet, and 3D Framework

Abstract

Four new Mn(II) coordination polymers [Mn(4,4′-bpy)(C6H5COO)2]n (1), [Mn(4,4′-bpy)(o-(NO2)C6H4COO)2]n (2), [Mn(4,4′-bpy)(m-(NO2)C6H4COO)2]n (3), and [Mn(4,4′-bpy)(p-(NO2)C6H4COO)2]n (4) (where 4,4′-bpy = 4,4′-bipyridine) have been synthesized by self-assembly of the primary ligands, benzoate and the o-, m-, and p-isomers of nitrobenzoates, respectively, together with 4,4′-bpy as the secondary spacer. All four complexes were characterized by elemental analyses, IR spectroscopy, single-crystal X-ray diffraction analyses, and variable-temperature magnetic measurements. The structural analyses reveal that complexes 1 and 3 are constructed by linear fused chains through double syn-syn (for 1) or syn-anti (for 3) carboxylate-bridged Mn(II), which are further linked to one another by trans coordinated 4,4′-bpy bridges, giving rise to a rectangular grid-like two-dimensional (2D) net. Complex 2 features one-dimensional (1D) molecular ladder formed by both syn-syn and syn-anti carboxylate-bridged dimeric Mn(II) uni...