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Metal‐Free Activation of Enthalpically Strong Bonds: Unraveling the Potential of Hitherto Unexplored Singlet Carbenes
Advanced Synthesis & Catalysis ( IF 4.4 ) Pub Date : 2018-10-16 , DOI: 10.1002/adsc.201800873 Priyam Bharadwaz 1 , Rian D. Dewhurst 2 , Ashwini K. Phukan 1
Advanced Synthesis & Catalysis ( IF 4.4 ) Pub Date : 2018-10-16 , DOI: 10.1002/adsc.201800873 Priyam Bharadwaz 1 , Rian D. Dewhurst 2 , Ashwini K. Phukan 1
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Density functional theory calculations have been carried out on a number of ambiphilic and electrophilic carbenes (both experimentally known and computationally designed) to understand their reactivity profile towards the activation of thermally robust bonds. Based on the calculated values of activation energy barriers, it was found that for ammonia (NH3), most of the molecules favor an electrophilic mode of activation. On the other hand, even though the electrophilic pathway is found to be more favorable than the nucleophilic one for activation of phosphine (PH2Ph) by majority of the carbenes, the barrier heights for both pathways are calculated to be comparable for diamidocarbene (DAC), cyclic amino aryl carbenes (CAArCs) and bicyclic alkyl amino carbene (BICAAC). In agreement with their better electron donation and acceptance abilities, the hitherto unexplored BICAAC, CAArCs and cyclic alkyl amido carbenes (CAAmC) are predicted to be more effective than cyclic alkyl amino carbenes (CAACs) towards the activation of both ammonia and phosphine. For the activation of silane (SiH3Ph), a hydride transfer pathway is found to be more favorable than the proton transfer pathway. Further, the calculated values of total Gibbs free energies and activation energy barriers for the splitting of N−H, P−H and Si−H bonds by a majority of the molecules are found to be comparable to those of the experimentally evaluated ones, implying that these known‐yet unexplored‐carbenes may be considered as suitable candidates for the activation of such enthalpically strong bonds.
中文翻译：
牢固结合的无金属活化：揭示迄今未开发的单线态碳烯的潜力
已经对许多两亲和亲电的卡宾（实验已知和计算设计）进行了密度泛函理论计算，以了解它们对活化热键的反应性。根据活化能垒的计算值，发现对于氨（NH 3），大多数分子倾向于亲电活化方式。另一方面，即使发现亲电途径比亲核途径更有利于磷化氢的活化（PH 2在大多数羧甲基苯酚中，两种途径的势垒高度经计算可与二酰胺基卡宾（DAC），环氨基芳基卡宾（CAArCs）和双环烷基氨基卡宾（BICAAC）相媲美。与其迄今未开发的BICAAC，CAArC和环状烷基酰胺基卡宾（CAAmC）具有更好的电子捐赠和接受能力相一致，预计在活化氨和膦方面比环状烷基氨基卡宾（CAAC）更有效。用于硅烷活化（SiH 3Ph），发现氢化物转移途径比质子转移途径更有利。此外，发现大部分分子将NH，PH和Si-H键分开的总吉布斯自由能和活化能垒的计算值与实验评估的值相当。这些已知但尚未开发的卡宾可被认为是激活这种焓强键的合适候选物。
更新日期：2018-10-16
中文翻译：
牢固结合的无金属活化：揭示迄今未开发的单线态碳烯的潜力
已经对许多两亲和亲电的卡宾（实验已知和计算设计）进行了密度泛函理论计算，以了解它们对活化热键的反应性。根据活化能垒的计算值，发现对于氨（NH 3），大多数分子倾向于亲电活化方式。另一方面，即使发现亲电途径比亲核途径更有利于磷化氢的活化（PH 2在大多数羧甲基苯酚中，两种途径的势垒高度经计算可与二酰胺基卡宾（DAC），环氨基芳基卡宾（CAArCs）和双环烷基氨基卡宾（BICAAC）相媲美。与其迄今未开发的BICAAC，CAArC和环状烷基酰胺基卡宾（CAAmC）具有更好的电子捐赠和接受能力相一致，预计在活化氨和膦方面比环状烷基氨基卡宾（CAAC）更有效。用于硅烷活化（SiH 3Ph），发现氢化物转移途径比质子转移途径更有利。此外，发现大部分分子将NH，PH和Si-H键分开的总吉布斯自由能和活化能垒的计算值与实验评估的值相当。这些已知但尚未开发的卡宾可被认为是激活这种焓强键的合适候选物。
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