Structure, magnetic properties and spin density of two alternative Mn(II) coordination polymers based on 1,4-bis(2'-carboxyphenoxy)benzene.

Two novel manganese coordination polymers [Mn 2 (μ 2 -bcpb)(μ 4 -bcpb)(2,2'-bipy) 2 ] n (1) and [Mn 2 (μ 3 -bcpb) 2 (2,2'-bipy) 2 (H 2 O)] n (2) (H 2 bcpb = 1,4-bis(2'-carboxylato phenoxy)-benzene; 2,2'-bipy = 2,2'-bipyridine), have been synthesized successfully from the same reactants. This unusual selectivity was corroborated by X-ray powder diffraction. Single crystal X-ray diffraction analysis of complex 1 reveals that neighboring Mn(II) ions are linked via two bcpb 2- anions to form a dinuclear Mn(II) subunit [Mn 2 (μ 1,1 -COO) 2 ] 2+ with a Mn⋯Mn distance of 3.3758 (6) Å. And π⋯π interactions between aromatic rings of the bcpb 2- and 2,2'-bipy ligands stabilize the two-dimensional extended coordination network with the unprecedented Schläfli symbols {4·6 2 } 2 {4 2 ·6 2 ·8 2 }. In the [Mn 2 (μ 1,3 -COO) 2 ] 2+ subunit of 2, two linking bcpb 2- ligands subtend an interaction distance of 4.4048(6) Å. Intermolecular O-H⋯O hydrogen bonds involving oxygen atoms of carboxylic acid and coordinated water molecules connect adjacent 1D chain molecules into a 2D network. Experimental temperature-dependent magnetic susceptibility measurements and spin density analyses by DFT disclose that compounds 1 and 2 display different magnetic properties.