Complexation of Np(v) with N,N-dimethyl-3-oxa-glutaramic acid and related ligands: thermodynamics, optical properties and structural aspects
作者:Linfeng Rao、Guoxin Tian、Simon J. Teat
DOI:10.1039/b922851a
日期:——
Complexation of Np(V) with N,N-dimethyl-3-oxa-glutaramic acid (DMOGA) was studied in comparison with its diamide analog, N,N,N′,N′-tetramethyl-3-oxa-glutaramide (TMOGA), and dicarboxylate analog, oxydiacetic acid (ODA). Thermodynamic parameters, including the stability constant and the enthalpy of complexation, were determined by spectrophotometry and calorimetry. Single-crystal structure of NpO2(H2O)(DMOGA)·H2O(c) was identified by X-ray diffractometry using synchrotron radiation. Like ODA and TMOGA, DMOGA forms a tridentate Np(V) complex, with three oxygen atoms coordinating to the linear NpO2+ moiety via the equatorial plane. The stability constants, enthalpy and entropy of complexation generally decrease in the order ODA > DMOGA > TMOGA, suggesting that the complexation is entropy driven and the substitution of a carboxylate group with an amide group reduces the strength of complexation with Np(V) due to the decrease in the entropy of complexation.
研究了 Np(V) 与 N,N-二甲基-3-氧杂-谷氨酸 (DMOGA) 的络合,并将其与二酰胺类似物 N,N,N′,N′-四甲基-3-氧杂-谷酰胺 (TMOGA) 和二羧酸类似物氧二乙酸 (ODA) 进行了比较。通过分光光度法和量热法测定了包括稳定常数和络合焓在内的热力学参数。通过同步辐射 X 射线衍射仪确定了 NpO2(H2O)(DMOGA)-H2O(c)的单晶结构。与 ODA 和 TMOGA 一样,DMOGA 形成了三叉Np(V) 复合物,三个氧原子通过赤道面与线性 NpO2+ 分子配位。络合的稳定常数、焓和熵一般按照 ODA > DMOGA > TMOGA 的顺序降低,这表明络合是由熵驱动的,用酰胺基团取代羧酸基团会降低与 Np(V) 的络合强度,因为络合熵降低了。