The stereomutations in a class of tris(pentafluorophenyl)borane-benzotriazole adducts are investigated by means of variable-temperature F-19 NMR and X-ray crystallography. At low temperature the presence of a pair of conformational enantiomers is confirmed by NMR spectra obtained in a chiral medium. Two different energy barriers, corresponding to an enantiomerization process and a B-N rotation, were observed and their values measured (Delta G double dagger = 10.7 and 12.8 kcal mol(-1) in the case of 1). In the case of the bis-adduct 3, two conformational diastereoisomers with different populations were detected at low temperature, while only one diastereoisomer is present in the crystalline state.
|Titolo:||Conformational behavior of tris(pentafluorophenyl)borane-benzotriazole adducts|
|Autori interni:||MERCANDELLI, PIERLUIGI (Penultimo)|
|Settore Scientifico Disciplinare:||Settore CHIM/03 - Chimica Generale e Inorganica|
|Data di pubblicazione:||2006|
|Digital Object Identifier (DOI):||10.1021/om051003t|
|Appare nelle tipologie:||01 - Articolo su periodico|