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

Crystals of M(NH)[N(CN)] with M = Ni and Co were obtained from the reaction of stoichiometric amounts of Na[N(CN)] with NiCl·6HO or CoCl·6HO in aqueous, ammoniacal solutions. X-ray single-crystal structure analyses show that M(NH)[N(CN)] with M = Ni and Co crystallize isotypically to each other and adopt the monoclinic space group P2/ c (no. 14). The lattice parameters of Ni(NH)[N(CN)] are a = 5.8498(9) Å, b = 10.6739(12) Å, and c = 6.8089(17) Å, β = 98.037(3)° and Z = 2, while those of Co(NH)[N(CN)] are a = 5.8303(11) Å, b = 10.746(2) Å, c = 6.7773(13) Å, and β = 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(NH)[N(CN)] shows that the dicyanamide moiety is a medium-field ligand. Additional superconducting quantum interference device (SQUID) magnetic susceptibility measurements of Ni(NH)[N(CN)] and Co(NH)[N(CN)] confirm not only significant high-spin moments of χ T = 1.24 cm·K·mol (μ = 3.15 μ) and 2.89 cm·K·mol (μ = 4.81 μ), respectively, at 290 K and 0.1 T but also an absence of magnetic ordering.