mixing technique used. Under conditions of excess chromium(II), more than the stoichiometric amount of Cr(III) products were isolated, indicating that some degree of substitution was occurring. Blank experiments established that the products obtained could have arisen from an outer-sphere reaction followed by capture of the free ligands by Cr(II). A synergistic effect between the acac and bipy ligands
[Co(bipy)2(ptdn)2+(bipy = 2,2t-联
吡啶和ptdn =
戊烷-2,4-二酮)的Cr(II)还原反应进行得太快,无法通过停流方法检测到,并且计算出该反应的下限为3×104 M-1 s-1(μ= 0.10 M(LiClO4)),[H +] = 0.030M。产品研究表明,同时形成了[Cr(bipy)(OH2)4] 3+和[Cr(bipy)(ptdn)(OH2)2] 2+。所获得产品的比例在很大程度上取决于所使用的混合技术。在过量的
铬(II)的条件下,分离出的
化学计量数量超过了Cr(III)的产物,这表明正在发生某种程度的取代。空白实验确定,所获得的产物可能是由外球反应继而由Cr(II)捕获游离
配体而产生的。acac和bipy
配体之间的协同作用似乎正在发挥作用。在停止流动的仪器上观察到两个反应。两者均归因于联
吡啶在Cr(III)上的闭环。得到[Cr(bipy)(OH2)4]