About the Aromaticity of symm-Triaminotrinitrobenzene

Abstract

Aromaticity and structural features of the isolated symm-triaminotrinitrobenzene (TATB) were examined using the nonempirical ab initio quantum chemical method and molecular dynamics at the Car–Parrinello level. Different criteria of the aromaticity were combined with the study of conformational flexibility of molecule and analysis of the electron density distribution. It was found that the cooperative effect of the resonance-assisted hydrogen bonds results in the ultimate decreasing aromaticity of the benzene ring in TATB. Values of the HOMA index indicate that it could be classified as low-aromatic in equilibrium state at zero temperature but completely nonaromatic at room temperature. An extremely high flexibility of the molecule is also not typical for aromatic rings. The electron delocalization in H-bonded ON–CC–N–H quasi-aromatic rings was found to be greater than that in the benzene ring of TATB.

Probing the Structural Effects of Hydrogen Bonding in 1,3,5-Triamino-2,4,6-trinitrobenzene (TATB): Experimental Evidence by 15N NMR Spectroscopy

“…These molecules adopt a near-planar conformation forming planes stacked into a 3-dimensional lattice. The bond lengths and atomic distances of the original structure not only support the notion of a network of intra- and intermolecular hydrogen bonds formed in the solid structure but also suggest an unusual aromaticity of the TATB molecule . Several modeling efforts have indicated this network of hydrogen bonds provides the observed stability (for examples see ref and and references therein).…”

“…The bond lengths and atomic distances of the original structure not only support the notion of a network of intraand intermolecular hydrogen bonds formed in the solid structure but also suggest an unusual aromaticity of the TATB molecule. 4 Several modeling efforts have indicated this network of hydrogen bonds provides the observed stability (for examples see ref 5 and 6 and references therein). While numerous experimental efforts have suggested these hydrogenbonding networks are present in the solid structure, 7−13 the challenging chemical properties of TATB have significantly hindered many additional experimental efforts.…”