Reactivity of a Tetra(o‐tolyl)diborane(4) Dianion as a Diarylboryl Anion Equivalent

Abstract

Lithium and magnesium salts of tetra(o-tolyl)diborane(4) dianion, having B = Bd ouble bond character, were synthesized. It was clarified that the lithium salt of the dianion has ah igh-lying HOMO and an arrowH OMO-LUMO gap,w hich were perturbed by dissociation of Li + cation, as judged by UV/Vis spectroscopya nd DFT calculations.The lithium salt of the dianion reacted as two equivalents of ad iarylboryl anion with CH 2 Cl 2 or S 8 to give borylsubstituted products.

2,2′-Bipyridyl as a Redox-Active Borylene Abstraction Agent

“…In addition to featuring boron in the formal +1 oxidation state, 11 diborenes are particularly intriguing as the conceptual dimers of borylene fragments, being potentially related to the latter through a Wanzlick-type equilibrium, 27 which has thus far not been observed 27f but that is conceptually close to the fact that diborane(4) dianions can react like two equivalents of boryl anion. 28 Thus, [(Me 3 P)MesB=BMes(PMe 3 )] (8) 29 was treated with one equivalent of 1 in benzene (Scheme 5). After six days at 80 °C, the 11 B NMR spectrum of the reaction mixture showed the complete disappearance of the signal for 8, which correlated with the liberation of free PMe 3 according to 31 Unfortunately, repeating the reaction several times led to formation of the two boroncontaining products 3b and 9 ( 11 B NMR resonances at δ = 23 (3b) and 46 (9)) in different ratios (even when more than two equivalents of 1 were used), along with thermal decomposition products of 8 the quantitative separation of these species from each other and from residual 1 12 was unsuccessful.…”

Ge=B π‐Bonding: Synthesis and Reversible [2+2] Cycloaddition of Germaborenes

“…To reduce the addition products 2 and 3 , reactions with magnesium were studied. The best results were obtained after activation of the magnesium with dibromoethane and addition of catalytic amounts of anthracene . Reductions were carried out in tetrahydrofuran at ambient temperature (Scheme ).…”

“…Thebest results were obtained after activation of the magnesium with dibromoethane and addition of catalytic amounts of anthracene. [8] Reductions were carried out in tetrahydrofuran at ambient temperature (Scheme 2). In the course of the reduction the colorless solution turned deep red, and the reduction products 4 and 5 were isolated as single crystals from ap entane solution.…”

Ge=B‐π‐Bindung: Synthese und reversible [2+2]‐Cycloaddition von Germaborenen

“…Die besten Ergebnisse wurden erzielt, indem zuerst das Magnesium mit Dibromethan aktiviert und anschließend katalytische Mengen Anthracen zugegeben wurden. [8] Die Reduktionen wurden in Te trahydrofuran bei Raumtemperatur durchgeführt (Schema 2). Während der Reduktion färbt sich das anfangs farblose Reaktionsgemisch dunkelrot, und die Reduktionsprodukte 4 und 5 konnten als Einkristalle aus Pentan erhalten werden.…”