A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Division of the Russian Academy of Sciences, 1 Favorsky Street, 664033 Irkutsk, Russia.
Department of Physical and Colloidal Chemistry, Ivanovo State University of Chemistry and Technology, Sheremetevkiy Ave, 7, 153000 Ivanovo, Russia.
Molecules. 2023 May 6;28(9):3933. doi: 10.3390/molecules28093933.
The molecular structure and conformational and rotational composition of 3,7,9-tris(trifluoromethylsulfonyl)-3,7,9-triazabicyclo[3.3.1]nonane have been investigated by synchronous gas-phase electron diffraction/mass spectrometry GED/MS and theoretical calculations (B3LYP and M06-2X with cc-pVTZ and aug-cc-pVTZ basis sets) and compared to the X-ray structure. All 16 possible conformers and rotamers were calculated, differing by the conformations of the two piperazine rings, orientation of the CF groups relative to these rings, and non-equivalence of the two wings of the butterfly structure. The optimized geometry of the most stable conformer coincides with that in the crystal. In contrast to only one conformer determined by X-ray, the GED analysis revealed the presence of five conformers, (), (), (), (), () in the ratio of :( + ):: = 36(10):42(6):22(10):0(10). The experimental results are better reproduced by calculations performed for 428 K (the temperature of the GED experiment) than for 298 K (standard), and most satisfactorily at the M06-2X/aug-cc-pVTZ level of theory.
已经通过同步气相电子衍射/质谱联用（GED/MS）和理论计算（B3LYP 和 M06-2X 与 cc-pVTZ 和 aug-cc-pVTZ 基组）研究了 3,7,9-三（三氟甲基磺酰基）-3,7,9-三氮杂双环[3.3.1]壬烷的分子结构和构象及旋转组成，并将其与 X 射线结构进行了比较。计算了所有 16 种可能的构象和旋转异构体，它们的区别在于两个哌嗪环的构象、CF 基团相对于这些环的取向以及蝴蝶结构的两个翅膀的不等价性。最稳定构象的优化几何形状与晶体中的一致。与 X 射线仅确定一种构象相反，GED 分析表明存在五种构象，（），（），（），（），（），其比例为：（）：（+）：（）：（）= 36(10)：42(6)：22(10)：0(10)。对于 428 K（GED 实验的温度）的计算结果比对于 298 K（标准）的计算结果更好地再现了实验结果，并且在 M06-2X/aug-cc-pVTZ 理论水平上的结果最为令人满意。
