Antiaromatic Dithieno-1,2-dihydro-1,2-diborin Splits Diatomic Hydrogen

Abstract

B,B-Dimesityl-substituted dithieno-1,2-dihydro-1,2-diborin was synthesized and its properties and reactivity were studied. Owing to the noticeably electron-deficient and antiaromatic character of the 1,2-dihydro-1,2-diborin ring, this compound was found to homolytically cleave diatomic hydrogen (H 2 ) gas at ambient temperature under 1 atm to afford a hydrogen-bridged bis(borane). This reaction was accompanied by a dramatic color change from dark green to yellow in addition to a turn-on fluorescence response.

Reactions of B2(o‐tolyl)4 with Boranes: Assembly of the Pentaborane(9), HB[B(o‐tolyl)(μ‐H)]4

“…Such tetraaryl‐substituted species (Figure 1 a) remained largely unexplored, until 2017 when Yamashita and co‐workers developed a one‐pot synthesis of the tetraaryldiborane(4), B 2 ( o ‐tolyl) 4 and demonstrated its ability to activate H 2 [16] . Later that same year, Yamaguchi and Piers [17] described the ability of the dithieno‐diborin to similarly react with H 2 . In 2018, Erker and co‐woorkers [18] reported the synthesis of the dissymmetric tetrasubstituted diborane(4) Ph(C 6 HR(C 6 F 5 )(SiMe 3 ))BB(C 6 F 5 ) 2 , while the Yamashita group reported the reactions of B 2 ( o ‐tolyl) 4 with CO, nitriles, azobenzene, and pyridazine [19] .…”

Tetraaryldiborane(4) Can Emit Dual Fluorescence Responding to the Structural Change around the B–B Bond

“…Diborane(4) derivatives are widely used in chemistry as reagents in organic synthesis and as building blocks for functional molecules [1–9] . Although diborane(4) derivatives without heteroatom substituents capable of lone‐pair donation are easily hydrolyzed, if chemically stable derivatives can be obtained without electronic stabilization by heteroatoms, they may exhibit interesting electronic properties arising from the neighboring vacant 2p orbitals of boron.…”

“…In this context, while tetraaryldiborane(4) is interesting, only a few isolable tetraaryldiborane(4) derivatives have been reported ( I – IV , Figure 1 a). [4–7] For instance, Power et al. reported that the arylation of tetramethoxydiborane(4) with mesityllithium gives rise to trimesitylmethoxydiborane(4) I′ , which can be converted to trimesitylphenyldiborane(4) I upon treatment with phenyllithium [4a] .…”

“…reported that the arylation of tetramethoxydiborane(4) with mesityllithium gives rise to trimesitylmethoxydiborane(4) I′ , which can be converted to trimesitylphenyldiborane(4) I upon treatment with phenyllithium [4a] . However, existing examples of tetraaryldiborane(4) lack chemical stability under atmospheric conditions, which limits the investigation of their properties [4–9] …”

Tetraaryldiborane(4) Can Emit Dual Fluorescence Responding to the Structural Change around the B–B Bond

“…Diborane (4) derivatives are widely used in chemistry as reagents in organic synthesis and as building blocks for functional molecules. [1][2][3][4][5][6][7][8][9] Although diborane(4) derivatives without heteroatom substituents capable of lone-pair donation are easily hydrolyzed, if chemically stable derivatives can be obtained without electronic stabilization by heteroatoms, they may exhibit interesting electronic properties arising from the neighboring vacant 2p orbitals of boron. In this context, while tetraaryldiborane( 4) is interesting,o nly af ew isolable tetraaryldiborane(4) derivatives have been reported (I-IV, Figure 1a).…”