Confirmation of an Early Postulate: BCB Two‐Electron–Three‐Center Bonding in Organo(hydro)boranes

Abstract

Bor kann's auch: Das erste dimere Organo(hydro)boran mit B‐B‐verbrückendem Arylring wurde charakterisiert (siehe Bild; B grün/blau, C schwarz/grau). Die Verbindung enthält eine B‐C‐B‐Zweielektronen‐Dreizentren‐Bindung und weitgehend ungestörte aromatische π‐Elektronensysteme.

BN‐Phenanthryne: Cyclotetramerization of an 1,2‐Azaborine Derivative

“…We reasoned that 1,2-azaborines might be generated by N 2 elimination and ring enlargement of azidoboroles, as earlier reports by Paetzold et al indicate that acyclic azidodiorganylboranes R 2 BN 3 rearrange thermally to iminoboranes RBNR without intermediate formation of borylnitrenes R 2 BN. [8,9] As azidoboroles are unknown and expected to be highly unstable, [10] we studied the thermal decomposition of the dibenzo derivative 9-azido-9-borafluorene 5. This compound was synthesized earlier by our group and found to be rather labile.…”

Extensive Structural Rearrangements upon Reduction of 9H‐9‐Borafluorene

“…Zuschriften compound exists as a C 1 -symmetric dimer with a B-B bridging phenylene ring, both in solution and in the solid state [(1) 2 ; Scheme 1]. [13] 2) The parent dimer (R = H) is not stable in solution over a long time period (contrary to its derivative R = tBu), but undergoes a ring-opening oligomerization reaction. [12] Herein, we will show that the very peculiar character of (1) 2 extends further into the area of its redox chemistry.…”

“…To exclude the potential influence of a Lewis basic solvent on the structural integrity of (1) 2 , [12,13,16] we used toluene rather than THF in the initial reduction experiments [from now on, (1) 2 refers exclusively to the derivative R = tBu]. Following the standard protocol, the compound was prepared from 9-Br-2,7-di-tBu-9-borafluorene and excess Et 3 SiH.…”

“…Our group is currently investigating the chemical behavior of pristine 9H-9-borafluorene (dibenzoborole). [12][13][14] In spite of its close formal relationship to B, 9H-9-borafluorene shows distinctly different structural features and reactivity: 1) The .…”

A Simple Link between Hydrocarbon and Borohydride Chemistries

“…The proton brings an empty 1s orbital perfectly suited to form 3c-2e bonds with the boron atoms of the 2c-2e BÀB bonds. In this work, we consider only the proton to generate 3c-2e bonds, but other groups that contain empty orbitals of suitable energy (for instance, B 3 + , BH 2 + , BH 2 + , or even CH 2 2 + [10] ) could also be appropriate.…”