Supramolecular Isomerism in Coordination Polymers of Isophthalato‐Bridged MnII Complexes Using 4,4′‐Dipyridyl N,N′‐Dioxide

Abstract

AbstractA one‐pot reaction of three components [MnII, isophthalate dianion (isop) and 4,4′‐dipyridyl N,N′‐dioxide (dpyo)] in water/methanol (1:1) causes self‐assembly resulting in two 3D supramolecular isomers of the same stoichiometry, {[Mn(isop)(H2O)2]·(dpyo)·(H2O)}n (colorless) (1) and {[Mn(isop)(H2O)(dpyo)0.5]·(dpyo)0.5·(H2O)2}n (pink) (2). Both isomers crystallize in the same crystal system (triclinic) and space group (P$\bar {1}$). The structural determination of 1 reveals an isophthalato‐bridged 1D coordination polymer, {[Mn(isop)(H2O)2]n, having 16‐ and 8‐membered rings where isophthalate acts simultaneously as chelating and bridging ligand connected to three metal centers. In isomer 2 the 1D chains transform to a 2D arrangement through bridging dpyo that replaces a water molecule at metal axial position. Both the crystal structures result in a 3D supramolecular network achieved through H‐bonding among the 1D (in 1) or 2D (in 2) coordination polymers with lattice water and dpyo molecules and also by means of π‐π interactions in 1. Low‐temperature magnetic measurement indicates antiferromagnetic interaction in both the isomers and the best fits are given by the exchange parameters J = –0.56 ± 0.02 cm–1, g = 2.01 ± 0.01 and R = 3.1 × 10–5 for 1 and J = –1.06 ± 0.03 cm–1, g = 2.01 ± 0.01 and R = 2.8 × 10–5 for 2.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)