A Hybrid Organic/Inorganic Benzene

Abstract

It isn't easy BN aromatic! 1,2‐Dihydro‐1,2‐azaborine, a hybrid organic/inorganic benzene, is a stable aromatic molecule with features that are distinct from its isoelectronic “organic” (benzene) and “inorganic” (borazine) counterparts. Experimental structural, spectroscopic, and chemical data are fully supported by high‐level calculations.

The boron–carbon–nitrogen heterocyclic rings

“…1). The NICS(0) and NICS(1) values of C 4 BN ring are in better agreement with previous calculations of Del Bene et al [17] and Marwitz et al [16]. These NICS values suggest that the degree of aromaticity of C 4 BN is slightly less than C 6 as expected due to presence of a polar BN bond.…”

“…The novelty of borocarbonitrides attracted us to investigate systematically the six membered rings formed by B, C and N atoms in the varying proportions of BN and C. There exist a few studies [16,17] on these BCN based six membered ring systems, also known as "azaborines". The systematic study performed by Del Bene et al includes five isomers of B 2 C 2 N 2 H 6 ring and one BC 4 NH 6 ring along with benzene and borazine [17].…”

Boron‐Substituted 1,3‐Dihydro‐1,3‐azaborines: Synthesis, Structure, and Evaluation of Aromaticity

“…5 kcal/mol (average of 3.5 and 6.6 kcal/mol) less than that of benzene (RSE = 34.1 kcal/mol). Compared to a similar analysis for the parent 1,2-azaborine (RSE = 21 kcal/mol), [21] the parent 1,3-azaborine exhibits a RSE that is higher, which is consistent with the structural analysis and NICS calculations.Thus, in terms of structure, magnetism, and resonance energy stabilization presented in this work, we conclude that 1,3-azaborines should be considered more aromatic than 1,2-azaborines. [22] It appears that the crucial factors governing the relative aromaticity between 1,2-and 1,3-azaborines originate in the extent of electron delocalization as well as the lack of a B-N bond in the 1,3-isomer.…”

Neutral Diboron Analogues of Archetypal Aromatic Species by Spontaneous Cycloaddition

“…Thus far, however, even the synthesis of such a simple molecule as the benzene analogue, 1,2-dihydro-1,2-azaborabenzene [BNC4H6], necessitates a complex seven-step route, [17] whereas the neutral borabenzene molecule [BC5H5] has thus far eluded synthesis. Requisite for controlled cycloaddition, stable, neutral compounds containing B-B multiple bonds remained unknown until the report in 2007 by Robinson and co-workers of the first Nheterocyclic carbene (NHC)-stabilized diborene.…”