Dysprosium Chlorocyanoanilate-Based 2D-Layered Coordination Polymers

A series of two-dimensional (2D)-layered coordination polymers (CPs) based on the heterosubstituted anilate ligand ClCNAn(2-) derived from 3-chloro-6-cyano-2,5-dihydroxybenzoquinone and Dy-III are reported. By changes in the synthetic methods (layering technique, solvothermal or conventional one-pot reactions) and conditions (solvent, concentration, etc.), different types of 2D extended networks could be prepared and structurally characterized. Compounds 1 and 1', two polymorphs with the formula [Dy-2(ClCNAn)(3)(DMSO)(6)](n)center dot(H2O) [x = 7 (1), 0 (1')], were prepared by a conventional one-pot reaction and recrystallized at different concentrations. Compound 2, formulated as [Dy-2(ClCNAn)(3)(DMF)(6)](n), was prepared by a layering technique, while compound 3, formulated as {(Me2NH2)(2)[Dy-2(ClCNAn)(4)(H2O)(2)]center dot(DMF)(2)center dot(H2O)(5)}(n), was obtained by a solvothermal method. Compounds 1 and 2 are neutral 2D CPs of the ClCNAn(2-) ligand and Dy-III ions, while 3 presents 2D anionic layers of [Dy-2(ClCNAn)(4)(H2O)(2)](2-) alternating with cationic layers of Me2NH2+ ions. These compounds show very diverse networks, with compound 1 forming 2D (8,3) and (4,3) topology with eight- and four-membered rings with square cavities, 1' and 2, respectively, a 2D (6,3) topology with six-membered rings (a rectangular cavity for 1' and a regular hexagonal cavity for 2), and 3 a 2D (4,4) topology with distorted square cavities. In this respect, 1 and 1' represent the first examples of polymorphism in the family of anilate-based CPs. Thermal analysis measurements (differential scanning calorimetry and thermogravimetry) show an exothermic polymorphic transformation from the kinetically stable 1' phase to the thermodynamically stable phase 1. The magnetic behavior of 1-3 very likely indicates depopulation of the m(J) levels, while the presence of weak antiferromagnetic coupling between the Dy-III centers mediated by the anilate bridge cannot be excluded.