Zhou Xiaoyu, Zhang Xue-Peng, Li Weikang, Jiang Jingxing, Xu Huiying, Ke Zhuofeng, Phillips David Lee, Zhao Cunyuan
MOE Key Laboratory of Bioinorganic and Synthetic Chemistry, School of Chemistry, Sun Yat-Sen University Guangzhou 510275 P. R. China
School of Chemisty and Chemical Engineering, Shaanxi Normal University Xi'an 710119 P. R. China.
RSC Adv. 2019 Nov 19;9(65):37696-37704. doi: 10.1039/c9ra06737j.
A theoretical approach was used to investigate the hydrolytic cleavage mechanisms of the bis(-nitrophenyl) phosphate (BNPP) catalyzed by Zn(ii)-complexes featuring uncoordinated nucleophiles. Ligand-based and alternative solvent-based nucleophilic attack reaction models are proposed. The p values of the Zn(ii)-bound water molecules or ligands in the [Zn(L H)(η-HO)(HO)] ( = 1, 2 and 3) complexes, as well as the dimerization tendency of the mononuclear Zn(ii)-complexes, were found to significantly influence the reaction mechanisms. The Zn(ii)-L complexes were found to be more favorable for the hydrolytic cleavage of the BNPP a ligand-based nucleophilic attack pathway. This was due to the lower p value for the deprotonation of the oxime ligand, the hard dimerization of the mononuclear Zn(ii)-L species, and the presence of an uncoordinated nucleophile. The origins of the uncoordinated reactions were systematically elucidated. The theoretical results reported here are in good agreement with experimental observations and more importantly, help to elucidate the factors that influence intermolecular nucleophilic attack reactions with coordinated/uncoordinated nucleophiles.
采用理论方法研究了具有未配位亲核试剂的锌（II）配合物催化双（对硝基苯基）磷酸酯（BNPP）的水解裂解机制。提出了基于配体和基于替代溶剂的亲核攻击反应模型。发现[Zn（LnH）（η-H2O）（H2O）]n +（n = 1、2和3）配合物中与锌（II）结合的水分子或配体的pKa值，以及单核锌（II）配合物的二聚化趋势，对反应机制有显著影响。发现锌（II）-L配合物更有利于通过基于配体的亲核攻击途径水解裂解BNPP。这是由于肟配体去质子化的pKa值较低、单核锌（II）-L物种的硬二聚化以及存在未配位的亲核试剂。系统地阐明了未配位反应的起源。此处报道的理论结果与实验观察结果高度一致，更重要的是，有助于阐明影响与配位/未配位亲核试剂的分子间亲核攻击反应的因素。
