Activation of Carbon Dioxide by 9-Carbene-9-borafluorene Monoanion: Carbon Monoxide Releasing Transformation of Trioxaborinanone to Luminescent Dioxaborinanone

Abstract

The first structurally characterized example of a trioxaborinanone (2) is produced by the reaction of a 9-carbene-9-borafluorene monoanion and carbon dioxide. When compound 2 is heated or irradiated with UV light, carbon monoxide (CO) is released, and a luminescent dioxaborinanone (3) is formed. Notably, carbon monoxide releasing molecules (CORMs) are of interest for their ability to deliver a specific amount of CO. Due to the turn-on fluorescence observed as a result of the conversion to 3, CORM 2 serves as a means to optically observe CO loss “by eye” under thermal or photochemical conditions.

Photochemically- and Thermally-Generated BN- and BNP-Doped Borafluorenate Heterocycles via Intramolecular Staudinger-Type Reactions

“…[1][2][3] Research efforts in this regard have engaged a broad array of synthetic chemists interested in fundamental chemical transformations, [4][5][6][7][8][9][10][11] as well as those concerned with uncovering new types of functional materials. 3,[12][13][14][15][16][17][18][19][20][21] Recently, our laboratory synthesized a series of borafluorene radicals, 22 cations, 23,24 and anions, [25][26][27][28][29] all of which rely on the key reaction of a neutral carbon donor ligand (Lewis base) and 9-bromo-9-borafluorene (Lewis acid). Reaction of the 9-carbene-9-borafluorene anion with carbon dioxide (CO2) resulted in the formation of a trioxaborinanone, which releases carbon monoxide (CO) to form a luminescent dioxaborinanone (Figure 1B).…”

“…Reaction of the 9-carbene-9-borafluorene anion with carbon dioxide (CO2) resulted in the formation of a trioxaborinanone, which releases carbon monoxide (CO) to form a luminescent dioxaborinanone (Figure 1B). 27 The carbene adduct of 9-phosphaketenido-9-borafluorene also loses CO under photochemical conditions to afford a BP-doped six-membered ring via a putative phosphinidene intermediate (Figure 1A). 30 The synthesis of these B-and BP-centered PAHs via the extrusion of a gaseous small-molecule inspired us to explore possible synthetic strategies to obtain related BN analogues.…”

Photochemically and Thermally Generated BN-Doped Borafluorenate Heterocycles via Intramolecular Staudinger-Type Reactions

“…Reaction of the 9-carbene-9-borafluorene anion with carbon dioxide (CO 2 ) resulted in the formation of a trioxaborinanone, which releases carbon monoxide (CO) to form a luminescent dioxaborinanone (Figure 1A). 43 The carbene adduct of 9-phosphaketenido-9-borafluorene also loses CO under photochemical conditions to afford a BP-doped sixmembered ring via a putative phosphinidene intermediate (Figure 1B). 46 The synthesis of these B-and BP-centered PAHs via the extrusion of a gaseous small-molecule inspired us to explore possible synthetic strategies to obtain related BN analogues.…”

Systematic Electronic and Structural Studies of 9-Carbene-9-Borafluorene Monoanions and Transformations into Luminescent Boron Spirocycles

“…Recently, we have been investigating the structure and bonding, reactivity, and materials properties of 9-carbene-9-borafluorenes. ,− While 9-borafluorene has become a popular building block in molecular chemistry, studies of chemically reduced borafluorenes are still rare. ,,, Previously, we reported the formation of borafluorene-based spirocycles resulting from the reaction of diketones and 9-carbene-9-borafluorene monoanion (Figure b) . Although the electronic structures differ significantly, the R 2 BO 2 moiety of our closed-shell compounds bear resemblance, in terms of connectivity, to open-shell boracyclic radicals and salts synthesized by Stephan (Figure c). , Most notably, the incorporation of borafluorene in the spirocycle produces fluorescent materials .…”