The second-order rate constants (k2) of one-electron reduction with CrII ion of methylated tropylium ions [C7H7 –n(CH3)n+ClO4–, n= 0–7] were determined in 10% hydrochloric acid at 25.0°C. Reduction peak potentials determined by means of triangular wave cyclic voltammetry and charge transfer energies with pyrene were compared with the rates of CrII ion reduction in terms of the effect of methyl substituents
在10中确定了甲基化对yl离子[C 7 H 7 – n(CH 3)n + ClO 4 –,n = 0–7]的Cr II离子一电子还原的二级速率常数(k 2)。25.0℃下的%
盐酸。就甲基取代基的影响而言,将通过三角波循环伏安法测定的还原峰电位和and的电荷转移能与Cr II离子还原速率进行了比较。log k 2值随甲基数的增加而线性降低,直至n= 4。然而,当n为5或6时,每个额外的甲基取代基的减速作用变小,并且第七甲基取代基加速还原。甲基取代基对碳阳离子的还原峰电位的影响与对Cr II离子还原的影响相似,从而产生线性相关性。Marcus处理表明Cr II离子的还原是通过外层机理进行的。pyr的电荷转移能与n = 0-6的离子的还原电位呈线性关系,但是当n为0时,会出现相当大的偏差电荷转移能与甲基化的对yl离子的LUMO能级成线性关系,为7。这表明六甲基和七甲基对yl离子的出乎意料的还原性