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

A novel Co−glutarate, Co[O2C(CH2)3CO2] (1), was synthesized as single crystals by the hydrothermal reaction of
CoCl2 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) Å, b = 4.8064(10) Å, c = 9.274(3) Å, β =
90.5(2)°, and Z = 4. The Co2+ centers are tetrahedrally coordinated to four oxygen atoms from the dicarboxylate
ligands. The anhydrous-pillared three-dimensional structure consists of infinite Co−CO2−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 Å (gauche) and 6.99 Å (anti). Magnetic measurement reveals that the predominant
magnetic interactions are antiferromagnetic below 14 K.