Boron photochemistry

The synthesis, properties, and reactivity of Lewis acidic aminoboranes

“…These computations were supported by experimental evidence, 5 was dissolved in "wet" CDCl 3 and left for 7 days in solution, as well as a solid sample of 5 was left out on the bench for a week, exposing it to atmospheric conditions. In both cases, a weak water adduct was observed in the 1 H, 11 B, and 19 F NMR spectra, however the change in the 11 B chemical shift from the parent species to the water adduct was less than 1 ppm (40.5 ppm vs 39.9 ppm, see ESI Figure S58 -S60). Similar observations can be seen in the 19 F NMR spectrum, supporting that the H 2 O adduct is quite weak, consistent with the calculated 1.63 Å long BO bond and 5.0 kcal/mol low adduction energy.…”

“…1 H NMR (400 MHz, Benzene-d6) δ: 6.96 (d, J = 5.4 Hz, 2H), 6.80 (t, 1H), 6.78 -6.71 (m, 2H). 11 To a solution of LiN(SiMe3)2 (138.3 mg, 0.8235 mmol) in Et2O (5 mL), in a 20 mL vial, ClB(C6F5)2 (313.2 mg, 0.8235 mmol) in Et2O (2 mL) was added dropwise and stirred for 1 h. The solvent was then removed in vacuo and the residue was dissolved in pentane. The mixture was then filtered into a 20 mL vial and left to crystallize at -35 o C to yield single crystals suitable for x-ray diffraction.…”

“…Specifically, sterically encumbered aminoboranes have found applications in organic materials as they have unique photochemical properties. [11][12][13][14][15] In these applications, the steric hinderance required to prevent the aminoborane from oligomerizing and precludes any Lewis acidity (Yamaguchi, Figure 1). However, Erker and co-workers reported the use of pentafluorophenyl substituents on boron to increase the Lewis acidity of aminoboranes, synthesizing (N-pyrrolyl)B(C 6 F 5 ) 2 and the saturated (Npyrrolidinyl)B(C 6 F 5 ) 2 analogue (Figure 1).…”

The Synthesis Properties and Reactivity of Lewis Acidic Aminoboranes

“…Exposure of aminoboranes 1-4 and 6 to acetonitrile did not appear to show any changes in the multinuclear NMR spectra, indicating that adduct formation is not favourable at room temperature. However, the more Lewis acidic 5 appears to form an adduct with acetonitrile when dissolved in CD 3 CN as observed in the 11 B NMR spectrum with a sharper upfield resonance at -3.2 ppm (ESI, Figure S50).…”

“…Specifically, sterically encumbered aminoboranes have found applications in organic materials as they have unique photochemical properties. [11][12][13][14][15] In these applications, the steric hinderance required to prevent the aminoborane from oligomerizing and precludes any Lewis acidity (Yamaguchi, Figure 1). However, Erker and co-workers reported the use of pentafluorophenyl substituents on boron to increase the Lewis acidity of aminoboranes, synthesizing (N-pyrrolyl)B(C 6 F 5 ) 2 and the saturated (Npyrrolidinyl)B(C 6 F 5 ) 2 analogue (Figure 1).…”