氯化物溶液中Pd(Ⅱ)配位水解行为研究

COORDINATION HYDROLYSIS BEHAVIOUR OF PALLADIUM(Ⅱ) IN CHLORIDE MEDIA

用紫外吸收光谱法研究了在较高氯离子浓度介质中Ｐｄ（Ⅱ）配位水解行为。结果表明，尽管溶液ｐＨ值升高能促进钯及其配位离子的水解，但其水解过程在很大程度上被在高浓度氯离子介质中形成的氯钯配合物［ＰｄＣｌｉ］２－ｉ（ｉ＝０—４）所抑制，在ｐＨ＜８时，钯水解所生成的氢氧根配位离子在溶液中的摩尔分数不超过１０％，其余的钯主要以氯钯配合物［ＰｄＣｌ４］２－形式存在。应用钯在溶液中的配位水解模型方程，得出了不同ｐＨ值溶液中钯的各种形式的配位离子分布情况。

The coordination hydrolysis behavior of Pd 2+ has been examined in chloride media solution by ultraviolet absorption spectrograph.The results indicate that although the high pH values of solution could promote the hydrolysis of Pd 2+ ,the hydrolysis procedure is strongly suppressed by the chloride palladium coordination compound (PdCl i ) 2- i (i=0—4) formed in the solution with a high concentration of chloride media.When the pH values of solution are less than 8.0,the hydroxy coordination compound accounted for less than 10% of the total palladium and the remainder is present principally as PdCl 2- 4. By use of the model equation derived from the coordination hydrolysis of Pd 2+ ,the distribution of various Pd 2+ species between pH6.0 and 10.0 is obtained. It is shown that only when the pH values are more than 8.5,the hydroxy palladium coordination species could be dominant over the major chloride coordination compound PdCl 2- 4.