88916-30-7Relevant academic research and scientific papers
Methylene Bridging Effect on the Structures, Lewis Acidities and Optical Properties of Semi-planar Triarylboranes
Doan, Thu-Hong,Chardon, Aurélien,Osi, Arnaud,Mahaut, Damien,Tumanov, Nikolay,Wouters, Johan,Champagne, Beno?t,Berionni, Guillaume
, p. 1736 - 1743 (2020/12/11)
Three synthetic methods towards semi-planar triarylboranes with two aryl rings connected by a methylene bridge have been developed. The fine-tuning of their stereoelectronic properties and Lewis acidities was achieved by introducing fluorine, methyl, methoxy, n-butyl and phenyl groups either at their exocyclic or bridged aryl rings. X-ray diffraction analysis and quantum-chemical calculations provided quantitative information on the structural distortion experienced by the near planar hydro-boraanthracene skeleton during the association with Lewis bases such as NH3 and F?. Though the methylene bridge between the ortho-positions of two aryl rings of triarylboranes decreased the Gibbs free energies of complexation with small Lewis bases by less than 5 kJ mol?1 relative to the classical Lewis acid BAr3, the steric shielding of the CH2 bridge is sufficient to avoid the formation of Lewis adducts with larger Lewis bases such as triarylphosphines. A newly synthesized spirocyclic amino-borane with a long intramolecular B?N bond that could be dissociated under thermal process, UV-irradiation, or acidic conditions might be a potential candidate in Lewis pairs catalysis.
9-Mesityl-9,10-dihydro-9-boraanthrylidene: A Probe of Structure and Reactivity for Aromatic Carbenes
Lapin, Stephen C.,Brauer, Beth-Ellen,Schuster, Gary B.
, p. 2092 - 2100 (2007/10/02)
Photolysis of 10-diazo-9-mesityl-9,10-dihydro-9-boraanthracene (1) causes loss of nitrogen and formation of 9-mesityl-9,10-dihydro-9-boraanthrylidene (BA).Direct irradiation leads first to the singlet carbene, which intersystem crosses to the triplet.Photosensitization with triplet 2-acetonaphthone gives the triplet carbene directly.The singlet carbene reacts with isopropyl alcohol to give the appropriate ether.The triplet carbene forms cyclopropanes nonstereospecifically from terminal olefins and abstracts hydrogen atoms from hydrocarbons and alcohols.Kinetic and product analysis shows that, in contrast to fluorenylidene, the rate of equilibrium between 1BA and 3BA is slow compared with most of the bimolecular reactions of the triplet.This is believed to be a consequence of the larger energy gap between ground-state 3BA and 1BA compared with that of fluorenylidene.The effect of carbene structure on the magnitude of this energy gap is discussed.
