A theoretical investigation of hydride bridging in chiral oxazaborolidine-borane adducts: The importance of electron correlation

Molecular-orbital calculations performed using the ab initio MP2/6-31G^** and semi-empirical AMI methods predict hydride bridging to be favoured in oxazaborolidine-borane adducts, in agreement with experiment but in contrast to the ab initio HF/6-31G^** method. These results indicate the importance of electron correlation effects for a correct theoretical description of the structure and energies of these bridged species of importance for mechanistic studies of asymmetric induction by chiral oxazaborolidine-borane adducts.