Temperature dependence of the electronic ground states of two mononuclear, six-coordinate copper(ii) centres
作者:Malcolm A. Halcrow、Colin A. Kilner、Joanna Wolowska、Eric J. L. McInnes、Adam J. Bridgeman
DOI:10.1039/b309071j
日期:——
Powdered [Cu(L2NH2)2][ClO4]2 (1; L2NH2=2,6-bishydrazonomethyl}pyridine) and [Cu(L2OH)2][ClO4]2 (2; L2OH=2,6-bisoximomethyl}pyridine) exhibit EPR spectra that are consistent with dz2}1 Cu(II) centres at 295 K. These slowly transform upon cooling to 5 K, to show g-values that more closely resemble dy2−z2}1, pseudo-Jahn–Teller elongated structures. Single crystal X-ray structures of 1·2(CH3)2CO and
粉末状[Cu(L 2 NH 2)2 ] [ClO 4 ] 2 (1 ; L 2 NH 2 =2,6-双肼基甲基}吡啶)和[Cu(L 2 OH)2 ] [ClO 4 ] 2 (2; L 2 OH = 2,6-双肟基甲基}吡啶)表现出EPR光谱与d z 2 } 1 Cu(II)中心在295 K处一致。冷却至5 K时它们缓慢转变,以显示更类似于d y 2 − z 2 } 1的g值,拟Jahn –柜员机拉长的结构。1 ·2(CH 3)2 CO和2 2(CH 3)2 CO的单晶X射线结构显示了预期的六坐标Cu(II)中心,其Cu–N键的长度与d z 2 } 1根据DF计算进行配置。重要的是,2的结构在100–300 K之间与温度有关,其Cu–N键长以与C一致的方式变化。电子病历数据。这EPR光谱,以及对晶体结构的TLS分析,强烈暗示这些变化不是动态Jahn-Teller病的结果。这些结果与[Cu(L