Reaction of pentaarylboroles with carbon monoxide: an isolable organoboron carbonyl complex

Reactivity of a Dihydrodiborene with CO: Coordination, Insertion, Cleavage, and Spontaneous Formation of a Cyclic Alkyne

“…[10] Highly Lewis acidic pentaphenylborole (BC4Ph5) was found to coordinate CO at boron before undergoing CO insertion into the borole ring. [11] This borole was also found to undergo H2 addition to the two endocyclic carbon atoms adjacent to boron. [12] More recently unsymmetrical diboranes have also started to show some promise for TM-free H2 and CO activation.…”

“…A 13 C{ 1 H, 11 B} NMR experiment showed Ccarbene and Calkylidene resonances at 225.5 and 151.7 ppm, respectively. The latter is close to the B=CArB resonances observed in a series of (aryl)(boryl)methylene boranes around 165 ppm.…”

“…Selected bond lengths (Å) and angles (°): 3a: N2-B2 1.409(4), B2-H2 1.07(3), C21-B2 1.543(4), B1a-C21 1.361(4), B1a•••H2 2.43(3), B1a-C1a 1.543(4), N1a-C1a 1.460(3), C21-B1a-C1a 167.9(3), B1a-C21-B2 99.8(2), B1a-C21-C22 120.5(2), B2-C21-C22 139.5(3); 3b: N2-B2 1.421(5), B2-H2 1.12(4), C21-B2 1.532(6), B1b-C21 1.469(7), B1b-H1b 1.02(5), B1b-C1b In solution under an atmosphere of CO, compound 2a was found to convert rapidly back to 1 (Scheme 2). [26] Under an atmosphere of argon, however, NMR spectroscopic monitoring over several days at room temperature revealed the slow transformation of 2a into a new species, 3, characterized by two broad 11 Removal of volatiles, extraction with benzene and recrystallization from pentane yielded red crystals of 3 suitable for X-ray crystallographic analysis. Similarly to compound 2, the asymmetric unit of 3 always contained two superimposed regioisomers, 3a and 3b (Fig.…”

Direct observation of a borane–silane complex involved in frustrated Lewis-pair-mediated hydrosilylations

“…For example, we have shown that perfluoropentaphenylborole 40 (V, Fig. 1, inset) is an extremely Lewis acidic compound that binds CO 41 and activates dihydrogen towards H-H bond cleavage. 42,43 In the latter reaction, an adduct of H2 with V is clearly implicated.…”

Hydrogen activation with perfluorinated organoboranes: 1,2,3-tris(pentafluorophenyl)-4,5,6,7-tetrafluoro-1-boraindene

“…This compound reacts with a variety of small molecules, 10,11 including dihydrogen (H2). 12,13 In this reaction, dihydrogen is heterolytically cleaved very rapidly by the organoborane alone.…”