双羟基脲与Fe(Ⅲ)的络合及氧化还原反应

Coordination and Redox Reaction of Dihydroxyurea With Fe(Ⅲ)

用分光光度法和循环伏安分析法研究了双羟基脲(DHU)与Fe(Ⅲ)的作用,结果表明,DHU与Fe3+能形成紫色配合物,配合物有二级或以上络合,形成的1∶1配合物分解速率对配合物来说为1级,在10℃下,c0(DHU)=c0(FeCl3)=1.0×10-3mol/L时,配合物表观一级分解速率常数k′=0.031 min-1。其配位方式可能是其分子中的N—O上的氧原子和另一个N—O上的氮原子与Fe3+配位。但形成的配合物不稳定,会发生配合物分子内氧化还原反应,电子从DHU分子转移到Fe(Ⅲ),Fe(Ⅲ)被还原为Fe(Ⅱ),而DHU被氧化。

The interaction of dihydroxyurea（DHU） with Fe（Ⅲ） was studied by spectrophotometry and cyclic voltammetry.The results show that DHU forms dark purple complex quickly after mixing with Fe（Ⅲ）.Whereas the complex formed is relatively unstable.The decomposition rate constant of the complex k′ is estimated to be 0.031 min-1 at 10 ℃ and c0（DHU）=c0（FeCl3）=1.0×10-3 mol/L.Chelation through the N—O oxygen atom and N—O nitrogen atom can be assumed for the complex.It is found that the innermolecular redox occurred between DHU and Fe（Ⅲ） after the formation of complex in solution.The one-electron transfer from DHU to Fe（Ⅲ） is assumed.Fe（Ⅲ） is reduced to Fe（Ⅱ）,at the same time DHU oxidation occurred.