Synthesis and Characterization of Iron Bispyridine Bisdicyanamide, Fe[C<sub>5</sub>H<sub>5</sub>N]<sub>2</sub>[N(CN)<sub>2</sub>]<sub>2</sub>
oleh: Laura Henrich, Peter C. Müller, Jan Hempelmann, Markus Mann, Jan van Leusen, Simon Steinberg, Richard Dronskowski
| Format: | Article |
|---|---|
| Diterbitkan: | MDPI AG 2023-06-01 |
Deskripsi
Fe[C<sub>5</sub>H<sub>5</sub>N]<sub>2</sub>[N(CN)<sub>2</sub>]<sub>2</sub> (<b>1</b>) was synthesized from a reaction of stoichiometric amounts of NaN(CN)<sub>2</sub> and FeCl<sub>2</sub>·4H<sub>2</sub>O in a methanol/pyridine solution. Single-crystal and powder diffraction show that <b>1</b> crystallizes in the monoclinic space group <i>I</i>2/<i>m</i> (no. 12), different from Mn[C<sub>5</sub>H<sub>5</sub>N]<sub>2</sub>[N(CN)<sub>2</sub>]<sub>2</sub> (<i>P</i>2<sub>1</sub>/<i>c</i>, no. 14) due to tilted pyridine rings, with <i>a</i> = 7.453(7) Å, <i>b</i> = 13.167(13) Å, <i>c</i> = 8.522(6) Å, <i>β</i> = 114.98(6)° and <i>Z</i> = 2. ATR-IR, AAS, and CHN measurements confirm the presence of dicyanamide and pyridine. Thermogravimetric analysis shows that π-stacking interactions of the pyridine rings play an important role in structural stabilization. Based on DFT-optimized structures, a chemical bonding analysis was performed using a local-orbital framework by projection from a plane-wave basis. The resulting bond orders and atomic charges are in good agreement with the expectations based on the structure analysis. SQUID magnetic susceptibility measurements show a high-spin state Fe<sup>II</sup> compound with predominantly antiferromagnetic exchange interactions at lower temperatures.