名称:
                                Synthesis and theoretical analysis of the structures and bonding in five new neutral square planar bis[2,4-di(aryl)-1,3,5-triazapentadienato]nickel(II) complexes
                             
                            
                                摘要:
                                Solvothermal reactions in methanol of nickel acetate tetrahydrate, Ni(OAC)(2) center dot 4H(2)O. with benzonitrile derivatives NC(C6H4)X, where X is one of the electron withdrawing substituents -CN, -NO2, or -CF3, located at the m- or p-positions relative to -CN, yield complexes of the general formula Ni{HN=C(R)-N=C(R)-NH}(2). More specifically, 3-nitrobenzonitrile, 4-nitrobenzonitrile, 1.3-dicyanobenzelle, 1,4-dicyanobenzene, and alpha alpha alpha-trifluoro-p-toluonitrile are found to react with Ni(OAc)(2) center dot 4H(2)O to yield Ni{HN=C(R)-N=C(R)-NH}(2), where R = 3-(NO2)C6H4, 4-(NO2)C6H4, 3-(CN)C6H4, 4-(CN)C6H4,. or 4-(CF3)C6H4, respectively. Analogous reactions of nitriles lacking electron withdrawing groups do not occur under similar conditions. Solid-state structures have been determined for the complexes with p-NO2, p-CN, and p-CF3 substituents on the phenyl rings. In addition, we describe density functional theory (DFT) and natural bonding orbital theory (NBO) studies on a simplified analog of these compounds, aimed at understanding their molecular bonding. It is shown that the new compounds for which solid-state structures have been determined are model examples of coordination compounds containing robust omega-bonds. (c) 2005 Elsevier B.V. All rights reserved.