State Key Laboratory of Physical Chemistry of Solid Surfaces and Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 360015, China.
Phys Chem Chem Phys. 2023 May 3;25(17):12072-12080. doi: 10.1039/d3cp01037f.
Substituent modification effects of N-heterocyclic carbene (NHC) boranes on their hydrogen atom abstraction (HAA) reactions and the chemical reactivities of corresponding NHC-boryl radicals have been investigated by density functional theory calculations. The substituent modification of NHC-boranes may notably affect the HAA reaction, both kinetically and thermodynamically, and shows remarkable substitution position dependence. The multi-site-modification of NHC-boranes is proved to be more effective for reduction of the B-H bond dissociation energy (BDE), promotion of the HAA reaction, and the reactivity regulation of their corresponding NHC-boryl radicals. Computational screening reveals that the spin density and the charge population of the radical boron center have good correlation with the B-H BDEs of NHC-boranes and the chemical reactivities of NHC-boryl radicals, and they can be considered as property and reactivity descriptors of these boron-based systems. The present results and established scaling relationships are beneficial to promote the advancement of design of NHC-boryl radical catalysis.
通过密度泛函理论计算研究了 N-杂环卡宾（NHC）硼烷的取代基修饰对其氢原子摘取（HAA）反应以及相应 NHC-硼基自由基的化学反应活性的影响。NHC-硼烷的取代基修饰可能会显著影响 HAA 反应的动力学和热力学，并且表现出显著的取代位置依赖性。证明了 NHC-硼烷的多部位修饰对于降低 B-H 键离解能（BDE）、促进 HAA 反应以及调节其相应 NHC-硼基自由基的反应性更为有效。计算筛选表明，自由基硼中心的自旋密度和电荷布居与 NHC-硼烷的 B-H BDE 和 NHC-硼基自由基的化学反应活性具有良好的相关性，它们可以作为这些硼基体系的性质和反应性描述符。本研究结果和建立的标度关系有助于促进 NHC-硼基自由基催化设计的进展。
