The Structure of Nickel(Ii) and Copper(Ii) Complexes with 1,4,8,11-Tetraazacyclotetradecanein Aqueous Solution as Studied by the X-Ray Diffraction Method |
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| Authors: | Hitoshi Ohtaki Hiroyuki Seki |
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| Institution: | 1. Coordination Chemistry Laboratories Institute for Molecular Science , Myodaiji-cho, Okazaki, 444, Japan;2. Department of Electronic Chemistry , Tokyo Institute of Technology at Nagatsuta Nagatsuta-cho , Midori-ku, Yokohama, 227, Japan |
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| Abstract: | The structure of 1,4,8,11-tetraazacyclotetradecane (cyclam) complexes with nickel(II) and copper(II) ions in aqueous solution has been determined by the x-ray diffraction method at 25°C. The Ni-(cyclam)]2+ complex has a square-planar structure with four nitrogen atoms of the cyclam, and the Ni-N bond length has been determined to be 198 pm. Upon the addition of ammonia, the color of the nickel(II)-cyclam solution turns to deep purple and the Ni(NH3)2(cyclam)]2+ complex is formed. The complex has a regular octahedral structure with an additional two NH3 molecules along the axis vertical of the cyclam plane, and the Ni-N (NH3 and cyclam) bond lengths are 209 pm. The copper(II)-cyclam complex in the aqueous solution is a distorted octahedron with two water molecules along the elongated axis. The axial Cu—O and equatorial Cu—N bond lengths are 277 and 210 pm, respectively. |
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