镨与间乙酰基偶氮氯膦配合物形成反应的分光光度法研究

Spectrophotometric Study on the Praseodymium-Chlorophosphonazo-m-COCH_3(CPAmA) Complex

文本报导用分光光度法研究间乙酰基偶氨氯膦的性质,及其与稀土元素镨的α型配合物的组成、吸收光谱、积累稳定常数(1gβ_3=49.59)。一定条件下镨的偶氮氯膦mA配合物可由α型转变为β型,α型是瞬时形成的,随着反应的进行α峰下降而β峰上升。在pH为2.02、Pr/CPAmA摩尔比为2∶1时,测得β型配合物形成反应的级数为一级,半衰期为8.4分,表观活化能为29.98kJ/mol。

The properties of chlorophosphonazo-m-COCH_3(CPAmA)and the composition,absorption spectrum and overall stability constant of its α-type complex with praseodymium are studied with spectrophotometric method. The formation of α-type complex of Pr-CPAmA has a relatively wide metal/ reagent mole ratio and wide pH range.The complex takes place quickly and is also very stable.But,the β-type complex is formed from α-type complex at the mole ratio of Pr/CPAmA 1.0～2.5 and pH range 1.68～2.10.Kinetic studies indicate that this is a first order reaction,its half time being 8.4 minutes and the apparent activation energy E_a= 29.98 kJ/mol.