Synthesis and crystal structure of a cadmium(II) coordination polymer based on
Anastasiia M Popovych1, Liudmyla V Tsymbal1, Dmytro M Khomenko2,3
1L. V. Pisarzhevskii Institute of Physical Chemistry of the National Academy of Sciences of Ukraine, Prospekt Nauki 31, 03028, Kyiv, Ukraine.
Abstract:
The asymmetric unit of the title compound, catena-poly[[[aqua-bis-(pyridine-κN)cadmium(II)]-μ2-4,4'-(1H-1,2,4-triazole-3,5-di-yl)dibenzoato-κ4 O,O':O'',O'''] 4.5-hydrate], {[Cd(C16H9N3O4)(C5H5N)2(H2O)]·4.5H2O} or {[Cd(bct)(py)2(H2O)]·4.5H2O} (I), consists of a Cd2+ cation coordinated to one bct2- carboxyl-ate dianion, two mol-ecules of pyridine and a water mol-ecule as well as four and a half water mol-ecules of crystallization. The metal ion in I possesses a penta-gonal-bipyramidal environment with the four O atoms of the two bidentately coordinated carboxyl-ate groups and the N atom of a pyridine mol-ecule forming the O4N equatorial plane, while the N atom of another pyridine ligand and the O atom of the water mol-ecule occupy the axial positions. The bct2- bridging ligand connects two metal ions via its carb-oxy-lic groups, resulting in the formation of a parallel linear polymeric chain running along the [11] direction. The coordinated water mol-ecule of one chain forms a strong O-H⋯O hydrogen bond with the carboxyl-ate O atom of a neighboring chain, leading to the formation of double chains with a closest distance of 5.425 (7) Å between the cadmium ions belonging to different chains. Aromatic π-π stacking inter-actions between the benzene fragments of the anions as well as between the coordinated pyridine mol-ecules belonging to different chains results in the formation of sheets oriented parallel to the (01) plane. As a result of hydrogen-bonding inter-actions involving the water mol-ecules of crystallization, the sheets are joined together in a three-dimensional network.
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