Reaction between 4-methyl-2,6-bis(pyrazol-1-ylmethyl)phenol (HL) or its 3,5-dimethylpyrazole derivative (HLâ²) and Cu(ClO4)2·6H2O afforded [CuII2(L/Lâ²)2(OClO3)2] 1 and 2. Complex 1 has been structurally characterized showing that each copper(II) centre is square pyramidal with two bridging phenoxide oxygens and two terminal pyrazole nitrogens in the equatorial plane and a perchlorate oxygen atom axially co-ordinated. Variable-temperature magnetic susceptibility measurements revealed that the dicopper(II) centres are strongly antiferromagnetically coupled [singletâtriplet energy separation, 2J (in cmâ1): â1204 for 1 and â798 for 2]. The complexes exhibit 1H NMR spectra within δ 0â10 due to their S = 0 ground state. In MeCN solution they exhibit ligand field transitions in the range 14 300â16 600 cmâ1 and phenolate-to-copper(II) charge-transfer transition at â22 700 cmâ1. In MeCN solution each complex displays three consecutive irreversible responses (scan rate of 50 mV sâ1) with Epc values (V vs. SCE) at â0.02, â0.54 and â0.86 (1) and 0.00, â0.42 and â0.80 (2). The first two responses are due to CuIIâCuI and the most cathodic response to CuIâCu0 redox processes, respectively.
4-甲基-2,6-双(
吡唑-1-基甲基)
苯酚(HL)或其
3,5-二甲基吡唑衍
生物(HLâ²)与 Cu(
ClO4)2Â-6H2O 反应生成了[CuII2(L/Lâ²)2(OClO3)2] 1 和 2。络合物 1 的结构特征显示,每个
铜(II)中心都是方形
金字塔,赤道面上有两个桥接的苯氧基和两个末端的
吡唑硝基,轴向有一个
高氯酸盐氧原子。变温磁感应强度测量结果表明,二
氯化
铜(II)中心具有很强的反
铁磁性耦合[单三极能量分离,2J(单位:cmâ1):1为1204,2为798]。由于它们的 SÂ =Â 0 基态,这些复合物显示出δ 0â10 范围内的 1H NMR 光谱。在 MeCN 溶液中,它们在 14Â 300â16Â 600 cmâ1 范围内显示出
配体场转变,在 â22Â 700 cmâ1 处显示出
苯酚到
铜(II)的电荷转移转变。在 MeCN 溶液中,每个复合物都显示出三个连续的不可逆反应(扫描速率为 50 mV sâ1),Epc 值(V vs. SCE)分别为§0.02、§0.54 和§0.86 (1) 以及 0.00、§0.42 和§0.80 (2)。前两种反应分别是由于 CuIIâCuI 和 CuIâCu0 氧化还原过程引起的最阴极反应。