SPATIAL STRUCTURE AND NONTRIVIAL STEREODYNAMICS OF TRICYCLIC PERHYDRO-1,2,4,5-TETRAZINES

Authors

  • Rafael R. Kostikov Institute of Chemistry, Saint Petersburg State University, 26 Universitetsky Ave., Saint Petersburg 198504
  • Tatiana A. Kornilova Institute of Chemistry, Saint Petersburg State University, 26 Universitetsky Ave., Saint Petersburg 198504
  • Alexander F. Khlebnikov Institute of Chemistry, Saint Petersburg State University, 26 Universitetsky Ave., Saint Petersburg 198504
  • Gennady V. Shustov Department of Chemistry, University of the Fraser Valley, 33844 King Road, Abbotsford, BC Canada V2S 7M8
  • Alexander Yu. Ivanov Institute of Chemistry, Saint Petersburg State University, 26 Universitetsky Ave., Saint Petersburg 198504
  • Vitaly V. Suslonov Institute of Chemistry, Saint Petersburg State University, 26 Universitetsky Ave., Saint Petersburg 198504
  • Nikolay V. Shesternin Institute of Chemistry, Saint Petersburg State University, 26 Universitetsky Ave., Saint Petersburg 198504
  • Mikhail A. Kuznetsov Institute of Chemistry, Saint Petersburg State University, 26 Universitetsky Ave., Saint Petersburg 198504

DOI:

https://doi.org/10.1007/4919

Keywords:

perhydro-1, 2, 4, 5-tetrazines, conformations of tricyclic perhydrotetrazines, DFT quantum-chemical calculations, variable temperature NMR spectra, X-ray structures

Abstract

Thermolysis of 6-aryl-1,5-diazabicyclo[3.1.0]hexanes in methanol leads to the respective dimers, 5,11-diaryltetrahydro-1H,7H-dipyrazolo[1,2-a:1',2'-d]tetrazines. X-ray structural analysis of these compounds reveals the perhydrotetrazine ring adopting a chair conformation with the equatorially fused five-membered rings and with the equatorial orientation of the aryl substituents. A hindered rotation of the aryl substituents around the C–Ar bonds was observed by low-temperature NMR. Another NMR-observed process that takes place at low temperature is a reversible isomerization of the major eeee conformer into a slightly less stable aeee isomer. Density functional theory calculations (B3LYP/6-31+G(d)) on the conformational transformations of the parent tricyclic perhydrotetrazine and its 5,11-diphenyl derivative are in good agreement with the experimental findings and reveal that a conformation with the orthogonal orientation of the planes of the aryl substituents in respect to the average plane of the six-membered ring has the lowest energy.

Author Biographies

Rafael R. Kostikov, Institute of Chemistry, Saint Petersburg State University, 26 Universitetsky Ave., Saint Petersburg 198504

Заведующий кафедрой органической химии, д. х. н., профессор

Mikhail A. Kuznetsov, Institute of Chemistry, Saint Petersburg State University, 26 Universitetsky Ave., Saint Petersburg 198504

Профессор, заведующий кафедрой органической химии СПбГУ

mak@mail.wplus.net

 

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Published

2019-03-11

Issue

Vol. 55 No. 2 (2019)

Section

Original Papers