Facile Energy Release from Substituted Dewar Isomers of 1,2‐Dihydro‐1,2‐Azaborinines Catalyzed by Coinage Metal Lewis Acids

Abstract

Molecular solar thermal systems (MOST) represent an auspicious solution for the storage of solar energy. We report silver salts as a unique class of catalysts, capable of releasing the stored energy from the promising 1,2‐dihydro‐1,2‐azaborinine based MOST system. Mechanistic investigations provided insights into the silver catalyzed thermal backreaction, concurrently unveiling the first crystal structure of a 2‐aza‐3‐borabicyclo[2.2.0]hex‐5‐ene, the Dewar isomer of 1,2‐dihydro‐1,2‐azaborinine. Quantification of activation energies by kinetic experiments has elucidated the advantageous energy outcomes associated with Lewis acid catalysts, a phenomenon corroborated through computational analysis. By means of low temperature NMR spectroscopy, mechanistic insights into the coordination of Ag+ to the 1,2‐dihydro‐1,2‐azaborinine were gained.

A BN-Benzvalene

“…In collaboration with the Bettinger group, we discovered that 1,2-azaborine undergoes a clean photoisomerization to BN-Dewar benzene upon UV light irradiation ( hv > 280 nm) . Subsequently, the BN-Dewar benzene species has been investigated as potential molecular solar thermal fuels, , new synthetic building blocks for 1,2-aminoborylated cyclobutane derivatives, and as a monomer for ring-opening metathesis polymerization . During our investigation of the photochemistry of 1,2-azaborines, we discovered that a C5-aryl-functionalized 1,2-azaborine (with N -TBS and B -Mes substitution) produced the BN-benzvalene isomer in addition to the BN-Dewar isomer upon photolysis (Scheme ).…”