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Computational, 1 H NMR, and X‐ray structural studies on 1‐arylurazole tetrazane dimers
Author(s) -
Martin Kenneth L.,
Breton Gary W.
Publication year - 2017
Publication title -
acta crystallographica section c
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.304
H-Index - 17
ISSN - 2053-2296
DOI - 10.1107/s2053229617010786
Subject(s) - dimer , chemistry , radical , crystallography , x ray , nuclear magnetic resonance spectroscopy , methyl group , group (periodic table) , stereochemistry , computational chemistry , physics , organic chemistry , quantum mechanics
Nitrogen‐centered urazole radicals exist in equilibrium with tetrazane dimers in solution. The equilibrium established typically favors the free‐radical form. However, 1‐arylurazole radicals bearing substituents at the ortho position favor the dimeric form. We were able to determine the structure of one of the dimers (substituted at both ortho positions with methyl groups), namely 1,2‐(2,4‐dimethylphenyl)‐2‐[2‐(2,4‐dimethylphenyl)‐4‐methyl‐3,5‐dioxo‐1,2,4‐triazolidin‐1‐yl]‐4‐methyl‐1,2,4‐triazolidine‐3,5‐dione, C 24 H 28 N 6 O 4 , via X‐ray crystallography. The experimentally determined structure agreed well with the computationally obtained geometry at the B3LYP/6‐311G(d,p) level of theory. The preferred syn conformation of these 1‐arylurazole dimers results in the two aromatic rings being proximate and nearly parallel, which leads to some interesting shielding effects of certain signals in the 1 H NMR spectrum. Armed with this information, we were able to decipher the more complicated 1 H NMR spectrum obtained from a dimer that was monosubstituted at the ortho position with a methyl group.