Synthesis and Characterization of Iron Bispyridine Bisdicyanamide, Fe[C 5 H 5 N] 2 [N(CN) 2 ] 2

Fe[C 5 H 5 N] 2 [N(CN) 2 ] 2 ( 1 ) was synthesized from a reaction of stoichiometric amounts of NaN(CN) 2 and FeCl 2 ·4H 2 O in a methanol/pyridine solution. Single-crystal and powder diffraction show that 1 crystallizes in the monoclinic space group I 2/ m (no. 12), different from Mn[C 5 H 5 N] 2 [N(CN) 2 ] 2 ( P 2 1 / c , no. 14) due to tilted pyridine rings, with a = 7.453(7) Å, b = 13.167(13) Å, c = 8.522(6) Å, β = 114.98(6)° and Z = 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 II compound with predominantly antiferromagnetic exchange interactions at lower temperatures.