Synthesis and structure determination of Co(HNCN)(2) and Ni(HNCN)(2)

摘要

Well-crystallized cobalt and nickel hydrogencyanamide, Co(HNCN)(2) and Ni(HNCN)(2), were synthesized from the corresponding ammonia complexes [M(NH3)(6)](2+) under aqueous cyanamide conditions. The X-ray and neutron powder data evidence the orthorhombic system and space group Pnnm. The cell parameters for Co(HNCN)(2) are a = 6.572(1), b = 8.805(2), c = 3.267(1) angstrom, and Z = 2; for the isotypic Ni(HNCN)(2), the cell parameters arrive at a = 6.457(1), b = 8.768(2), c = 3.230(1) angstrom. The octahedral coordinations of the metal ions are marginally squeezed, with interatomic distances of 4 x Co-N = 2.134(5) angstrom, 2 x Co-N = 2.122(9) angstrom, and 4 x Ni-N = 2.133(6) angstrom, 2 x Ni-N = 2.035(11)angstrom. The HNCN- units appear as slightly bent (177.5(2)degrees for Co(HNCN)(2) and 175.7(2)degrees for Ni(HNCN)(2)) and exhibit cyanamide shape character due to triple- and single-bond C-N distances (1.20(2) vs. 1.33(2) angstrom for Co(HNCN)(2) and 1.15(2) vs. 1.38(2) angstrom for Ni(HNCN)(2)). The infrared vibration data compare well with those of the three existing alkali-metal hydrogencyanamides. (c) 2006 Elsevier Inc. All rights reserved.