| Summary: | Two different phase-pure cobalt(II) cyanoguanidine bromide coordination compounds, Co(C<sub>2</sub>N<sub>4</sub>H<sub>4</sub>)<sub>2</sub>(H<sub>2</sub>O)<sub>4</sub>·2Br·2H<sub>2</sub>O (<b>1</b>) and Co<sub>3</sub>(C<sub>2</sub>N<sub>4</sub>H<sub>4</sub>)<sub>8</sub>(H<sub>2</sub>O)<sub>8</sub>·6Br (<b>2</b>), were precipitated from aqueous and methanol solutions, respectively, and their structures were solved and refined from X-ray single-crystal data at 100 K. Both <b>1</b> and <b>2</b> crystallize in the triclinic system with space group <i>P</i><inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mover><mn>1</mn><mo>¯</mo></mover></mrow></semantics></math></inline-formula>. The structure of <b>1</b> consists of two crystallographically distinct isolated CoO<sub>4</sub>N<sub>2</sub> octahedral units plus bromide anions and crystal water molecules, whereas <b>2</b> is built from both isolated octahedra and discrete binuclear cluster units made from edge-sharing octahedra. Diffuse reflectance spectra and IR analysis then go on to highlight optical and vibrational differences between these two compounds. The magnetic susceptibility of <b>1</b> is consistent with either isolated or very weakly interacting Co<sup>2+</sup> centers whereas the magnetic susceptibility of <b>2</b> evidences the potential weak antiferromagnetic exchange interactions that may arise from superexchange within the binuclear clusters.
|
|---|