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1,3,2,5-Diazadiborinine featuring nucleophilic and electrophilic boron centres.

Wu D, Kong L, Li Y, Ganguly R, Kinjo R - Nat Commun (2015)

Bottom Line: In marked contrast to the reactivity of benzene, borazine, and even azaborinines previously reported, 1,3,2,5-diazadiborinine readily forms the adducts with methyl trifluoromethanesulfonate and phenylacetylene without any catalysts.Moreover, 1,3,2,5-diazadiborine activates carbon dioxide giving rise to a bicycle[2,2,2] product, and the binding process was found to be reversible.These results, thus, demonstrate that 1,3,2,5-diazadiborinine features both nucleophilic and electrophilic boron centres, with a formal B(+I)/B(+III) mixed valence system, in the aromatic six-membered B2C2N2 ring.

View Article: PubMed Central - PubMed

Affiliation: Division of Chemistry and Biological Chemistry, Nanyang Technological University, 21 Nanyang Link, 637371 Singapore, Singapore.

ABSTRACT
The seminal discovery in 1865 by Kekulé that benzene nucleus exists with cyclic skeleton is considered to be the beginning of aromatic chemistry. Since then, a myriad of cyclic molecules displaying aromatic property have been synthesized. Meanwhile, borazine (B3N3H6), despite the isostructural and isoelectronic relationships with benzene, exhibits little aromaticity. Herein, we report the synthesis of a 1,3,2,5-diazadiborinine (B2C2N2R6) derivative, a hybrid inorganic/organic benzene, and we present experimental and computational evidence for its aromaticity. In marked contrast to the reactivity of benzene, borazine, and even azaborinines previously reported, 1,3,2,5-diazadiborinine readily forms the adducts with methyl trifluoromethanesulfonate and phenylacetylene without any catalysts. Moreover, 1,3,2,5-diazadiborine activates carbon dioxide giving rise to a bicycle[2,2,2] product, and the binding process was found to be reversible. These results, thus, demonstrate that 1,3,2,5-diazadiborinine features both nucleophilic and electrophilic boron centres, with a formal B(+I)/B(+III) mixed valence system, in the aromatic six-membered B2C2N2 ring.

No MeSH data available.


Results of density functional theory calculations.Calculated NICS(0) and NICS(1) values for 4′, benzene, 1,2-azaborine, 1,3-azaborine and B3N3H6. Calculated at the B3LYP/6-311+G(d,p) level of theory.
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f3: Results of density functional theory calculations.Calculated NICS(0) and NICS(1) values for 4′, benzene, 1,2-azaborine, 1,3-azaborine and B3N3H6. Calculated at the B3LYP/6-311+G(d,p) level of theory.

Mentions: To evaluate the aromatic property of 4, the nucleus-independent chemical-shift values NICS(0) and NICS(1) were calculated for parent 1,3,2,5-diazadiborinine 4′, benzene (C6H6), 1,2-azaborine, 1,3-azaborine and B3N3H6 (Fig. 3). The NICS values for 4′ are less negative than those of benzene and 1,3-azaborine, but comparable to those of 1,2-azaborine, and more negative with respect to those of B3N3H6. Thus, it is predicted that 1,3,2,5-diazadiborinine features aromaticity, which seems smaller than those of benzene and 1,3-azaborine, but greater than that of B3N3H6. To estimate the resonance stabilization energy (RSE) of the parent 1,3,2,5-diazadiborinine 4′, we performed further computational analysis. The RSE value of 4′ is ∼22.4 kcal mol−1 less than that of benzene (34.1 kcal mol−1), which is smaller than those of 1,3-azaborinine (RSE=29 kcal mol−1) (ref. 31) and 1,2-azaborinine (RSE=21 kcal mol−1) (ref. 32).


1,3,2,5-Diazadiborinine featuring nucleophilic and electrophilic boron centres.

Wu D, Kong L, Li Y, Ganguly R, Kinjo R - Nat Commun (2015)

Results of density functional theory calculations.Calculated NICS(0) and NICS(1) values for 4′, benzene, 1,2-azaborine, 1,3-azaborine and B3N3H6. Calculated at the B3LYP/6-311+G(d,p) level of theory.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4490389&req=5

f3: Results of density functional theory calculations.Calculated NICS(0) and NICS(1) values for 4′, benzene, 1,2-azaborine, 1,3-azaborine and B3N3H6. Calculated at the B3LYP/6-311+G(d,p) level of theory.
Mentions: To evaluate the aromatic property of 4, the nucleus-independent chemical-shift values NICS(0) and NICS(1) were calculated for parent 1,3,2,5-diazadiborinine 4′, benzene (C6H6), 1,2-azaborine, 1,3-azaborine and B3N3H6 (Fig. 3). The NICS values for 4′ are less negative than those of benzene and 1,3-azaborine, but comparable to those of 1,2-azaborine, and more negative with respect to those of B3N3H6. Thus, it is predicted that 1,3,2,5-diazadiborinine features aromaticity, which seems smaller than those of benzene and 1,3-azaborine, but greater than that of B3N3H6. To estimate the resonance stabilization energy (RSE) of the parent 1,3,2,5-diazadiborinine 4′, we performed further computational analysis. The RSE value of 4′ is ∼22.4 kcal mol−1 less than that of benzene (34.1 kcal mol−1), which is smaller than those of 1,3-azaborinine (RSE=29 kcal mol−1) (ref. 31) and 1,2-azaborinine (RSE=21 kcal mol−1) (ref. 32).

Bottom Line: In marked contrast to the reactivity of benzene, borazine, and even azaborinines previously reported, 1,3,2,5-diazadiborinine readily forms the adducts with methyl trifluoromethanesulfonate and phenylacetylene without any catalysts.Moreover, 1,3,2,5-diazadiborine activates carbon dioxide giving rise to a bicycle[2,2,2] product, and the binding process was found to be reversible.These results, thus, demonstrate that 1,3,2,5-diazadiborinine features both nucleophilic and electrophilic boron centres, with a formal B(+I)/B(+III) mixed valence system, in the aromatic six-membered B2C2N2 ring.

View Article: PubMed Central - PubMed

Affiliation: Division of Chemistry and Biological Chemistry, Nanyang Technological University, 21 Nanyang Link, 637371 Singapore, Singapore.

ABSTRACT
The seminal discovery in 1865 by Kekulé that benzene nucleus exists with cyclic skeleton is considered to be the beginning of aromatic chemistry. Since then, a myriad of cyclic molecules displaying aromatic property have been synthesized. Meanwhile, borazine (B3N3H6), despite the isostructural and isoelectronic relationships with benzene, exhibits little aromaticity. Herein, we report the synthesis of a 1,3,2,5-diazadiborinine (B2C2N2R6) derivative, a hybrid inorganic/organic benzene, and we present experimental and computational evidence for its aromaticity. In marked contrast to the reactivity of benzene, borazine, and even azaborinines previously reported, 1,3,2,5-diazadiborinine readily forms the adducts with methyl trifluoromethanesulfonate and phenylacetylene without any catalysts. Moreover, 1,3,2,5-diazadiborine activates carbon dioxide giving rise to a bicycle[2,2,2] product, and the binding process was found to be reversible. These results, thus, demonstrate that 1,3,2,5-diazadiborinine features both nucleophilic and electrophilic boron centres, with a formal B(+I)/B(+III) mixed valence system, in the aromatic six-membered B2C2N2 ring.

No MeSH data available.