The [3+2] cycloaddition (32CA) reaction between trifluoroacetonitrile N-oxide (NO 7) and 2,2,4,4-tetramethyl-3-thioxocyclobutan-1-one (THK 12) as well as the self-dimerization of NO 7 as a competitive pathway were studied within the Molecular Electron Density Theory (MEDT) using several DFT functionals together with def2-TZVP basis set. Taking CCSD(T)/TZVP activation energies as reference, among the employed functionals, just the B2PLYP-D3(BJ) one is able to portray complete predominance of 32CA reaction over self-dimerization process in excellent agreement with the experimental outcomes. Analysis of the global reactivity indices permits to characterize NO 7 and THK 12 as a strong electrophile and a strong nucleophile, respectively, while analysis of the Parr functions allows explaining the chemo- and regioselectivity observed experimentally. The electron localization function (ELF) analysis of several points along the IRC profile associated with the energetically most favorable reaction channel permits to establish a non-concerted two-stage one-step molecular mechanism for this polar pmr-type 32CA reaction.

三氟乙腈N-氧化物（NO 7）与2,2,4,4-四甲基-3-硫代环丁-1-酮（THK 12）之间的[3 + 2]环加成（32CA）反应以及三聚乙炔的自二聚在分子电子密度理论（MEDT）中使用几种DFT功能以及def2-TZVP基础集研究了NO 7作为竞争途径。以CCSD（T）/ TZVP活化能为参考，在所采用的功能中，仅B2PLYP-D3（BJ）能够描绘出32CA反应完全胜过自二聚过程，与实验结果非常吻合。对全球反应活性指数的分析可以表征NO 7和THK 12分别作为强亲电试剂和强亲核试剂，而对Parr功能的分析则可以解释实验观察到的化学选择性和区域选择性。沿着IRC轮廓上与能量最有利的反应通道相关的几个点的电子定位功能（ELF）分析，可以为该极性pmr型32CA反应建立一个未经证实的两阶段单步分子机制。