title: 1,3,2,5-Diazadiborinine featuring nucleophilic and electrophilic boron centres.
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.
authors.affiliation: Division of Chemistry and Biological Chemistry, Nanyang Technological University, 21 Nanyang Link, 637371 Singapore, Singapore.
authors.forename: Di
authors.initials: D
authors.lastname: Wu
authors.affiliation: Division of Chemistry and Biological Chemistry, Nanyang Technological University, 21 Nanyang Link, 637371 Singapore, Singapore.
authors.forename: Lingbing
authors.initials: L
authors.lastname: Kong
authors.affiliation: NTU-CBC Crystallography Facility, Nanyang Technological University, 21 Nanyang Link, 637371 Singapore, Singapore.
authors.forename: Yongxin
authors.initials: Y
authors.lastname: Li
authors.affiliation: NTU-CBC Crystallography Facility, Nanyang Technological University, 21 Nanyang Link, 637371 Singapore, Singapore.
authors.forename: Rakesh
authors.initials: R
authors.lastname: Ganguly
authors.affiliation: Division of Chemistry and Biological Chemistry, Nanyang Technological University, 21 Nanyang Link, 637371 Singapore, Singapore.
authors.forename: Rei
authors.initials: R
authors.lastname: Kinjo