Center for Catalytic Hydrocarbon Functionalization (CCHF), Department of Chemistry, Center for Advanced Scientific Computing and Modeling (CASCaM), University of North Texas , 1155 Union Circle, #305070, Denton, Texas 76203-5017, United States.
J Phys Chem A. 2013 Sep 26;117(38):9245-51. doi: 10.1021/jp404951e. Epub 2013 Sep 11.
High accuracy correlation consistent Composite Approach (ccCA) calculations have been used to investigate methane C-H bond activation with alkali metal imidyl and alkaline earth metal imide complexes. Alkali metals (Li, Na) and alkaline earth metals (Be, Mg) are used in this research given their redox innocence, namely, M(+) and M(2+), respectively. The ccCA calculations for methane activation by imidyl radical NH(•-) and triplet nitrene NH(••) show a thermodynamic (ΔΔH = 13.2 kcal/mol) and kinetic (ΔΔH(‡) = 15.9 kcal/mol) preference for the former. Methane activation by LiNH(•) and MgNH proceeds via hydrogen atom abstraction (HAA) and [2 + 2] transition states; only HAA pathways are isolated for NaNH and BeNH. The ccCA computed enthalpies lead to the hypothesis that the nucleophilicity of the nitrogen of the activating ligand (NR) is the key ingredient in activating the strongest sp(3) C-H bonds like that of methane.
已使用高精度相关一致复合方法 (ccCA) 计算来研究与碱金属亚氨基和碱土金属亚胺配合物的甲烷 C-H 键活化。鉴于其氧化还原惰性，即 M(+) 和 M(2+)，本研究使用碱金属 (Li、Na) 和碱土金属 (Be、Mg)。亚氨基自由基 NH(•-)和三重态硝酰基 NH(••)对甲烷的 ccCA 计算表明，前者在热力学 (ΔΔH = 13.2 kcal/mol) 和动力学 (ΔΔH(‡) = 15.9 kcal/mol) 上具有优势。LiNH(•)和 MgNH 对甲烷的活化通过氢原子抽提 (HAA) 和 [2 + 2] 过渡态进行；NaNH 和 BeNH 仅分离出 HAA 途径。ccCA 计算的焓导致这样的假设，即活化配体 (NR) 的氮的亲核性是激活最强的 sp(3) C-H 键（如甲烷）的关键因素。
