Orbital interaction between electron lone pair and carbonyl group in N-trifluoroacetylpiperidine and N-piperidine amides: Planar and non-planar nitrogen bond configurations

Shlykov, Sergey A.; Phien, Tran Dinh; Trang, Nguyen Hoang

doi:10.1016/j.tet.2017.07.031

Cited by 6 publications

(1 citation statement)

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“…In the past, we have used B3LYP or M06-2X in the GED studies of cyclic molecules of similar complexity [3][4][5]. Higher levels of theory require overwhelming computational resources to be practical for such large molecules of low symmetry.…”

Section: Theoretical Calculationsmentioning

confidence: 99%

Gas-Phase Structure of 3,7,9-tris(trifluoromethylsulfonyl)-3,7,9-triazabicyclo[3.3.1]nonane by GED and Theoretical Calculations

Shainyan,

Eroshin,

Mukhina

et al. 2023

Molecules

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The molecular structure and conformational and rotational composition of 3,7,9-tris(trifluoromethylsulfonyl)-3,7,9-triazabicyclo[3.3.1]nonane 1 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 CF3 groups relative to these rings, and non-equivalence of the two wings of the butterfly structure. The optimized geometry of the most stable 1-c-out-2-c-out 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, 1-c-out-2-c-out (I), 1-c-in-2-c-out (II), 1-c-out-2-c-in (III), 1-b-out-2-c-out (IV), 1-c-out-2-b-out (V) in the ratio of I:(II + III):IV:V = 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.

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Section: Theoretical Calculationsmentioning

confidence: 99%