Hydrolysis of phosphate esters catalyzed by copper(II)-triamine complexes. The effect of triamine ligands on the reactivity of the copper(II) catalysts
Hydrolysis of phosphate esters catalyzed by copper(II)-triamine complexes. The effect of triamine ligands on the reactivity of the copper(II) catalysts
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DOI：
10.1016/s0020-1693(98)00222-9
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发表时间：
1998-12
影响因子：
2.8
通讯作者：
T. Itoh;Hiroyuki Hisada;Y. Usui;Y. Fujii
中科院分区：
文献类型：
--
作者：
T. Itoh;Hiroyuki Hisada;Y. Usui;Y. Fujii
铜（II）-三胺配合物催化2，4-二硝基苯基磷酸乙酯锂（7）和2，4-二硝基苯基磷酸二乙酯（8）的水解（三胺=顺式，顺式-三氨基环己烷（1）、1，5，9-三氮杂环十二烷（2）、1，4，7-三氮杂环壬烷（3）、二亚丙基三胺（4）、N-亚丙基三胺（5）、N-亚丙基三胺（6）、N-亚丙基三胺（7）、N-亚丙基三胺（8）、N-亚丙基三胺（9）、N-亚丙基三胺（10）、（2-氨乙基）-1，3-丙二胺（5），二亚乙基三胺（6））的催化活性，发现催化剂的活性以5 × 6 × 4 < 3 < 1 < 2的顺序增加。从pH依赖的表观速率常数，和去质子化常数（pKa）的配位水，活性物种被证实是CuL（OH）+的所有催化剂。此外，基于CuL（OH）+与磷酸二乙酯的混合络合物的稳定常数（Kester−1）的倒数（9）与米氏常数Km（1-4）之间的良好拟合以及μ-（磷酸二乙酯基）-（二亚丙基三胺）铜（II）六氟磷酸盐（10）的晶体结构分析，证实反应经由磷酸酯配位的中间体进行。此外，还发现速率常数（kcat）的递增顺序（5 × 6 × 4 × 3 < 1 × 2）与三胺配体配位强度的递减顺序密切对应。讨论了三胺配体的作用与中心铜离子的刘易斯酸性及反应机理的关系。
Hydrolyses of lithium 2,4-dinitrophenyl ethyl phosphate (7) and 2,4-dinitrophenyl diethyl phosphate (8) catalyzed by copper(II)—triamine complexes (triamine = cis,cis-triaminocyclohexane (1), 1,5,9-triazacyclododecane (2), 1,4,7-triazacyclononane (3), dipropylenetriamine (4), N-(2-aminoethyl)-1,3-propanediamine (5), diethylenetriamine (6)) were investigated at pH 7.0–9.5, and the reactivity of the catalysts was found to increase in the order 5 ∼ 6 ∼ 4 < 3 < 1 < 2. From the pH dependence of the apparent rate constants, and the deprotonation constant (pKa) of the coordinated water, the active species was confirmed to be CuL(OH)+for all of the catalysts. Furthermore, the reactions were confirmed to proceed via a phosphate ester-coordinated intermediate on the basis of a good fit between the reciprocal of the stability constant (Kester−1) of a mixed complex of CuL(OH)+with diethyl phosphate (9) and the Michaelis constant KMfor 1–4, and of crystal structure analysis of μ-(diethyl phosphato)-(dipropylenetriamine)copper(II) hexafluorophosphate (10). In addition, it was found that the increasing order (5 ∼ 6 ∼ 4 ≪ 3 < 1 ∼ 2) in the estimated rate constant (kcat) corresponded closely to the decreasing order in the coordination strength of triamine ligands. The effect of triamine ligands was discussed in relation to the Lewis acidity of central copper(II) ion and the reaction mechanism.