当前位置: X-MOL 学术Inorg. Chem. › 论文详情
Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)
Highly Active Carbene Potassium Complexes for the Ring-Opening Polymerization of ε-Caprolactone
Inorganic Chemistry ( IF 4.6 ) Pub Date : 2017-11-16 00:00:00 , DOI: 10.1021/acs.inorgchem.7b01892
Mrinal Bhunia 1 , Gonela Vijaykumar 1 , Debashis Adhikari 2 , Swadhin K. Mandal 1
Affiliation  

Herein we report the synthesis of two complexes of potassium employing strongly nucleophilic carbenes, such as cyclic “(alkyl)(amino)carbene (cAAC) and abnormal N-heterocyclic carbene (aNHC). Both complexes are dimeric in the solid state and the two potassium centers are bridged by trimethylsilylamide. In these complexes, the carbene- - -K interaction is predominantly electrostatic in character, which has been probed thoroughly by NBO and AIM analyses. Indeed, the delocalization energy of the cAAC lone pair calculated from the second-order perturbation theory was only 5.21 kcal mol–1, supporting a very weak interaction. The solution-state behavior of these molecules, as inferred from NOESY spectra, hints that the weak carbene- - -K interaction is retained in nonpolar solvents, and the bond is not dissociated at least on the NMR time scale. We took advantage of such a weak interaction to develop highly effective ring-opening polymerization catalysts for ε-caprolactone and rac-lactide. The efficacy of these catalysts is prominent from a very high substrate/metal-initiator ratio as well as very low dispersity index of the obtained polymer chains, reflecting significant control over polymerization.

中文翻译:

高活性碳钾络合物用于ε-己内酯的开环聚合

本文我们报告采用强亲核卡宾,诸如循环“(烷基)(氨基)卡宾(钾的两种配合物的合成Ç AAC)和异常N-杂环卡宾(一个NHC)。两种络合物都是固态的二聚体,并且两个钾中心被三甲基甲硅烷基酰胺桥接。在这些络合物中,卡宾--K相互作用主要为静电性质,已通过NBO和AIM分析进行了深入研究。实际上,根据二阶扰动理论计算出的c AAC孤对的离域能仅为5.21 kcal mol –1,支持非常弱的互动。从NOESY光谱推断,这些分子的溶液状态行为暗示了弱的碳烯---K相互作用保留在非极性溶剂中,并且键至少在NMR时间尺度上没有解离。我们利用这种弱相互作用来开发用于ε-己内酯和外消旋丙交酯的高效开环聚合催化剂。这些催化剂的功效从非常高的底物/金属引发剂比率以及所获得的聚合物链的非常低的分散指数而突出,这反映了对聚合的显着控制。
更新日期:2017-11-16
down
wechat
bug