Synthesis and Characterization of Iron Bispyridine Bisdicyanamide, Fe[C5H5N]2[N(CN)2]2.

Fe[C5H5N]2[N(CN)2]2 (1) was synthesized from a reaction of stoichiometric amounts of NaN(CN)2 and FeCl2·4H2O in a methanol/pyridine solution. Single-crystal and powder diffraction show that 1 crystallizes in the monoclinic space group I2/m (no. 12), different from Mn[C5H5N]2[N(CN)2]2 (P21/c, no. 14) due to tilted pyridine rings, with a = 7.453(7) Å, b = 13.167(13) Å, c = 8.522(6) Å, ß = 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 FeII compound with predominantly antiferromagnetic exchange interactions at lower temperatures.

Syntheses and Characterization of Diammine-Nickel/Cobalt(II)-Bisdicyanamide M(NH3)2[N(CN)2]2 with M = Ni and Co.

Crystals of M(NH3)2[N(CN)2]2 with M = Ni and Co were obtained from the reaction of stoichiometric amounts of Na[N(CN)2] with NiCl2·6H2O or CoCl2·6H2O in aqueous, ammoniacal solutions. X-ray single-crystal structure analyses show that M(NH3)2[N(CN)2]2 with M = Ni and Co crystallize isotypically to each other and adopt the monoclinic space group P21/ c (no. 14). The lattice parameters of Ni(NH3)2[N(CN)2]2 are a = 5.8498(9) Å, b = 10.6739(12) Å, and c = 6.8089(17) Å, ß = 98.037(3)° and Z = 2, while those of Co(NH3)2[N(CN)2]2 are a = 5.8303(11) Å, b = 10.746(2) Å, c = 6.7773(13) Å, and ß = 96.422(3)°. In addition, the crystal structure of the nickel compound was refined from neutron powder diffraction, augmented by DFT calculations as regards atomic displacement parameters. The IR spectra of the title compounds exhibit modes typical for the dicyanamide anion and ammonia. The UV/vis spectrum of Ni(NH3)2[N(CN)2]2 shows that the dicyanamide moiety is a medium-field ligand. Additional superconducting quantum interference device (SQUID) magnetic susceptibility measurements of Ni(NH3)2[N(CN)2]2 and Co(NH3)2[N(CN)2]2 confirm not only significant high-spin moments of χm T = 1.24 cm3·K·mol-1 (µeff = 3.15 µB) and 2.89 cm3·K·mol-1 (µeff = 4.81 µB), respectively, at 290 K and 0.1 T but also an absence of magnetic ordering.