北京大学魏俊年团队报道了二氮镥配合物的单甲基化和质子化。相关研究成果发表在2024年6月18日发表在《美国化学会杂志》。

由于高度的化学惰性，二氮的直接活化和转化具有挑战性。

该文中，研究人员报道了了由镥络合物支持的(N₂)^3-的合成、分离和衍生。最初，通过用金属钾还原中性镥-二氮络合物 [{(C₅Me₅){MeC(NⁱPr)₂}Lu}₂(μ²-η²:η²-N₂)][K(crypt)] (crypt = 2,2,2-cryptand)，生成了一个(N₂)^3-自由基。随后，(N₂)^3-络合物与三氟甲磺酸甲酯（或三氟甲酸）反应形成N–C（或N–H）键，产生相应的产物[{(C5Me5){MeC(NiPr)₂}Lu}₂(NN-R)(OTf)][K(crypt)] (R = Me, H, OTf = CF₃SO₃) 。

电子顺磁共振波谱和密度泛函理论分析都支持NN-Me单元的自由基性质。(NN-Me)^•2–自由基复合物中的Lu–N键主要是离子键，77%的不成对电子位于（NN-Me）片段上。此外，通过双杂化密度泛函理论优化的纯有机自由基(NN-Me)^•2–的几何结构，与(NN-Me)^•2–镥络合物的几何结构非常匹配。

附：英文原文

Title: Monomethylation and -protonation of Lutetium Dinitrogen Complex

Author: Xiao Chen, Gao-Xiang Wang, Ze-Jie Lv, Junnian Wei, Zhenfeng Xi

Issue&Volume: June 18, 2024

Abstract: Due to the highly chemically inert nature, direct activation and transformation of dinitrogen are challenging. Here, we disclose the synthesis, isolation, and derivatization of (N2)3– supported by lutetium complex. Initially, a (N2)3– radical, in [{(C5Me5){MeC(NiPr)2}Lu}2(μ2-η2:η2-N2)][K(crypt)] (crypt = 2,2,2-cryptand) complex, was generated through the reduction of neutral lutetium dinitrogen complex [{(C5Me5){MeC(NiPr)2}Lu}2(μ2-η2:η2-N2)] with potassium metal. Subsequently, the reaction of (N2)3– complex with methyl triflate (or triflic acid) led to the formation of an N–C (or N–H) bond, yielding the corresponding [{(C5Me5){MeC(NiPr)2}Lu}2(NN-R)(OTf)][K(crypt)] (R = Me, H, OTf = CF3SO3) as the product. Both electron paramagnetic resonance spectroscopy and density functional theory analyses support the radical character of the NN-Me unit. The Lu–N bonds in the (NN-Me)2– radical complex are predominantly ionic, with 77% of the unpaired electron localized on the (NN-Me) fragment. Moreover, the geometry of the pure organic radical (NN-Me)2–, optimized by double-hybrid density functional theory, closely matches that of the (NN-Me)2– lutetium complex.

DOI: 10.1021/jacs.4c05492

Source: https://pubs.acs.org/doi/abs/10.1021/jacs.4c05492