Formation of a borylene by photolysis of an overcrowded bis(methylseleno)borane

Formation and Reactivity of Electron‐Precise B−B Single and Multiple Bonds

“…Thee ven more strongly reducing diisopropyldiborene 51 [E 1/2 = À1.95 V] was subsequently prepared, with electrondonating isopropyl substituents at boron. [65] As well as being [99] Thes ame reaction in the presence of dimethyldisulfide provided the corresponding trisulfadiborolane.T he plausibility of this mechanism was recently established by our group,byobtaining arelated 5-membered heterocycle,c ompound 69,b yt he insertion of elemental sulfur into isolated diborene 49 b,w hich represents af ourelectron oxidation of the diborene fragment (Scheme 18 b). [100] Reaction of diborene 49 a with excess Se or Te also resulted in reduction of the chalcogen, although conversely,in this case the products, 70 a and 70 b,contained strained, threemembered B 2 Eh eterocycles (Scheme 18 c).…”

“…Cyclic voltammetry measurements performed on NHC-and phosphine-stabilized diborenes, 50 b and 53 b,r espectively, showed the occurrence of oxidation events at highly negative potentials [50 b 1.55 and 0.51 V; 53 b 1.05 V]. [65] As well as being oxidized by [C 7 H 7 ][BAr [99] Thes ame reaction in the presence of dimethyldisulfide provided the corresponding trisulfadiborolane.T he plausibility of this mechanism was recently established by our group,byobtaining arelated 5-membered heterocycle,c ompound 69,b yt he insertion of elemental sulfur into isolated diborene 49 b,w hich represents af ourelectron oxidation of the diborene fragment (Scheme 18 b). In contrast, the oxidation of the dppm-stabilized cis-diborene 54 b occurs at much higher potential [E 1/2 = À0.51 V],i mplying ac onsiderably less-electron-rich system.…”

Computational Study of van der Waals Complexes between Borylenes and Hydrocarbons

“…Arylborylene was invoked as an intermediate in the reduction of arylboron dihalides that yield borafluorenyls by intramolecular insertion into a CC σ bond 5. Another arylborylene, TbtB (Tbt=2,4,6‐tris[bis(trimethylsilyl)methyl]phenyl), was concluded to be an intermediate in the photolysis of TbtB(SeMe) 2 based on trapping with phenanthrenequinone to give dioxaborolene 6. In the experiments discussed above, the existence of borylenes was inferred indirectly from the products that were formed.…”

“…[5] Another arylborylene, TbtB (Tbt = 2,4,6-tris[bis(trimethylsilyl)methyl]phenyl), was concluded to be an intermediate in the photolysis of TbtB-(SeMe) 2 based on trapping with phenanthrenequinone to give dioxaborolene. [6] In the experiments discussed above, the existence of borylenes was inferred indirectly from the products that were formed. Borylenes could be directly observed by infrared (IR) spectroscopy under cryogenic matrix isolation condi-tions.…”

Reductive Insertion of Elemental Chalcogens into Boron–Boron Multiple Bonds

“…[30] A triselenodiborolane was synthesized by the UV-irradiation of ab ulky di(methylseleno)arylborane [Eq. [31] It was postulated that the formation of the triselenodiborolane resulted from the insertion of elemental selenium, produced during the course of the irradiation, into the B=Bb onds of diborenes formed in situ. [31] It was postulated that the formation of the triselenodiborolane resulted from the insertion of elemental selenium, produced during the course of the irradiation, into the B=Bb onds of diborenes formed in situ.…”