A Coordination Polymer of Cobalt(II)−Glutarate:  Two-Dimensional Interlocking Structure by Dicarboxylate Ligands with Two Different Conformations

Abstract

A novel Co-glutarate, Co[O(2)C(CH(2))(3)CO(2)] (1), was synthesized as single crystals by the hydrothermal reaction of CoCl(2) with glutaric acid in the presence of KOH and characterized by single-crystal X-ray diffraction analysis, TGA, IR, UV-vis reflectance spectrometry, and SQUID measurements. The dark purple Co-glutarate crystallizes in the monoclinic system in the space group P2/c, with a = 14.002(3) A, b = 4.8064(10) A, c = 9.274(3) A, beta = 90.5(2)degrees, and Z = 4. The Co(2+) centers are tetrahedrally coordinated to four oxygen atoms from the dicarboxylate ligands. The anhydrous-pillared three-dimensional structure consists of infinite Co-CO(2)-Co inorganic layers, which are stacked by the coordinated glutarate alkyl chain along the a-axis. There are two different conformations for glutarate ligands, i.e., the gauche- and the anti-forms. These ligands reside between the inorganic layers alternatively to separate each layer by 7.01 A (gauche) and 6.99 A (anti). Magnetic measurement reveals that the predominant magnetic interactions are antiferromagnetic below 14 K.