Synthesis, Characterization, and Density Functional Theory Studies of Three-Dimensional Inorganic Analogues of 9,10-Diboraanthracene—A New Class of Lewis Superacids

Abstract

The three-dimensional inorganic analogues of 9,10-diboraanthracene, B2X2(C2B10H10)2 (X = Cl, 1; X = Br, 2), were attained by salt elimination of Li2C2B10H10 and trihaloboranes. The methyl- and phenyl-substituted compounds B2Me2(C2B10H10)2 (3) and B2Ph2(C2B10H10)2 (4) were obtained by treating 1 or 2 with the corresponding Grignard reagents. These compounds were fully characterized by NMR, cyclic voltammetry (CV), IR, and single-crystal X-ray diffraction analyses. Experimental (CV and Gutmann–Beckett method) and computational (fluoride ion affinity, hydride ion affinity and LUMO energy) results suggest that the order of Lewis acidity is 2 > 1 > 4 > 3 > SbF5. Treatment of 1 or 2 with HSiEt3 gave a rare neutral borane–silane adduct, (Et3SiH)2B2H2(C2B10H10)2 (5). The equilibrium of 5 in solution was thoroughly investigated by spectroscopy and quantum calculations.

Highly selective electrophilic B(9)-amination of o-carborane driven by HOTf and HFIP

“…Carboranes, a class of boron–carbon molecular clusters with 3D aromaticity, 1 are found to have great application as useful building blocks in materials science, 2 catalysis, 3 supramolecular design, 4 organometallic and coordination chemistry, 5 and medicine. 6 Therefore, methods for the synthesis of functional carboranes have been widely explored, particularly in terms of B–H bond activation.…”

A Three‐Dimensional Inorganic Analogue of 9,10‐Diazido‐9,10‐Diboraanthracene: A Lewis Superacidic Azido Borane with Reactivity and Stability

“…[8] Inspired by the fascinating features of DBAs and following the two-dimensional/ three-dimensional (2D/3D) relationship between benzyne and carboryne, [9] we designed and successfully synthesized the first 3D analogues of DBA, in which the benzyne units are replaced by o-carboryne groups. [10] Indeed, our experimental and computational results revealed the Lewis superacidity at the bridging trigonal planar boron centers, which should be induced by the strong electron withdrawing effect of the o-carborane cage [11] and its minimized π-interaction with the vacant porbital of boron. Given the paucity of 2D 9,10-diazido-DBA, which is of considerable synthetic challenge, we herein set out to synthesize and investigate its first 3D inorganic analogue.…”

“…DBAs, their doubly reduced derivatives (DBA) 2− as well as the N‐heterocyclic carbene (NHC) stabilized derivatives demonstrated unique photophysical properties and diverse reactivity, allowing for the applications in ligand design, [3] olefin polymerization, [4] luminescent materials, [5] dihydrogen‐ and hydride‐transfer catalysis, [6] small molecule activation, [6, 7] and fluoride complexation [8] . Inspired by the fascinating features of DBAs and following the two‐dimensional/ three‐dimensional (2D/3D) relationship between benzyne and carboryne, [9] we designed and successfully synthesized the first 3D analogues of DBA, in which the benzyne units are replaced by o ‐carboryne groups [10] . Indeed, our experimental and computational results revealed the Lewis superacidity at the bridging trigonal planar boron centers, which should be induced by the strong electron withdrawing effect of the o ‐carborane cage [11] and its minimized π‐interaction with the vacant p‐orbital of boron.…”

Competition for Hydride Between Silicon and Boron: Synthesis and Characterization of a Hydroborane‐Stabilized Silylium Ion

“…[6] Piers, Tuononen and co‐workers eventually achieved the isolation of the related adduct 1 by employing 1,2,3‐tris(pentafluorophenyl)‐4,5,6,7‐tetrafluoro‐1‐boraindene instead of B(C 6 F 5 ) 3 (Scheme 1 , top). [7] Since 2014, additional examples of intermolecular Si−H bond activation with Al(C 6 F 5 ) 3 as in 2 , [8] a borenium ion as in 3 [B(C 6 F 5 ) 4 ] [9] as well as a neutral borane as in 4 [10] have been disclosed. The understanding of these intermediates is highly relevant to catalysis, especially in the case of Piers’ chemistry.…”