Reactivity of a coordinated inorganic acetylene unit, HBNH, and the azidoborane cation [HB(N₃)]⁺

Abstract

Isolable complexes of HBNH and [B(H)N3]+ have been prepared and their attempted conversion into bulk boron nitride was investigated. These studies yielded important insights into the reactivity of HBNH, an inorganic acetylene analogue.

Synthesis of Complex Boron–Nitrogen Heterocycles Comprising Borylated Triazenes and Tetrazenes Under Mild Conditions

“…Contrary to examples of Lewis adducts between boranes and covalent azides, which sometimes lead to dinitrogen extrusion and nitrene-like insertion reactions (Scheme ), , the reaction of either a stoichiometric amount or an excess of phenyl azide (PhN 3 ) with 1,2-dibromo-1,2-diduryldiborane(4) ( Dur 2 B 2 Br 2 ) or 1,2-dichloro-1,2-dimesityldiborane(4) ( Mes 2 B 2 Cl 2 ) does not lead to gas evolution, despite clear signs of reaction, such as the appearance of new 11 B NMR signals at higher field than those of the starting materials ( 1a , 61.7 and −2.2 ppm; 1b , 63.4 and 5.9 ppm) and a color change from colorless to orange. The 11 B NMR chemical shifts at ∼60 ppm are characteristic of arylboranes in a tricoordinate environment, while the signals at ∼0 ppm are indicative of a tetracoordinate boron environment.…”

“…The reactivity of boron-containing species with organic azides or of boron azides themselves has been generating renewed , interest lately (Scheme ). − An intriguing case is the development of ring-expansion reactions on boroles using various aryl azides. − These reactions have provided several surprising reactivity patterns and often highly exotic heterocyclic boron species. Interestingly, no reactivity between azides and diboranes(4) has been reported to date.…”

Dehydrogenation of Amine–Boranes Using p‐Block Compounds

“…In addition to i Pr 2 N=BH 2 , Rivard and co‐workers reported a zwitterionic aminoborane ( 2 ), which can be considered a donor–acceptor complex of the parent iminoborane HB≡NH, that is also able to abstract dihydrogen from Me 2 NH⋅BH 3 (Scheme ) . When 2 was reacted with Me 2 NH⋅BH 3 for 12 hours at room temperature, the hydrogenated product 3 formed along with the expected dehydrogenation by‐products [Me 2 N−BH 2 ] 2 and Me 2 NH−BH 2 −NMe 2 −BH 3 , which were detected by NMR spectroscopy.…”

Diborane(4) Azides: Surprisingly Stable Sources of Transient Iminoboranes

“…Attempts at forming diborane(4) azides from tetrahalodiboranes(4) and their derivatives showed even less controllable decomposition reactions that have so far only yielded intractable mixtures, all of which are indicative of the breakage of the B−B bond to a large extent in the products (see Supporting Information). The predisposition of diborane(4) azides to form transient nitrene‐like species was hypothesized to be due to the intramolecular activation of the azide, by analogy with borane‐triggered decompositions of some azides . A reasonable strategy to hinder such intramolecular activation would be the saturation of the empty p orbital at boron through π‐donation, for example with amine functional groups.…”