Racemization mechanism of lithium tert-butylphenylphosphido-borane: A kinetic insight

The racemization mechanism of tert-butylphenylphosphido-borane is investigated experimentally and theoretically. Based on this converging approach, it is shown, first, that several phosphido-borane molecular species coexist at the time of the reaction and, second, that one particular of both initially assumed reactive routes most significantly contribute to the overall racemization process. From our converging modeling and experimental measurement, it comes out that the most probable species to be here encountered is a phosphido-borane-Li (THF)(2) neutral solvate, whose P-stereogenic center monomolecular inversion through a Y-shaped transition structure (Delta(r)G degrees(not equal): 81 kJ mol(-1)) brings the largest contribution to the racemization process.

Automated summary

The racemization mechanism of tert-butylphenylphosphido-borane was investigated experimentally and theoretically, revealing the presence of multiple molecular species during the reaction and the significant contribution of a specific reactive route to the overall racemization process. The study suggests that a phosphido-borane-Li (THF)(2) neutral solvate with P-stereogenic center undergoes monomolecular inversion through a Y-shaped transition structure, playing a key role in the racemization process.