Lewis Acidic Boranes, Lewis Bases, and Equilibrium Constants: A Reliable Scaffold for a Quantitative Lewis Acidity/Basicity Scale.

ABSTRACT: A quantitative Lewis acidity/basicity scale toward boron-centered Lewis acids has been developed based on a set of 90 experimental equilibrium constants for the reactions of triarylboranes with various O-, N-, S-, and P-centered Lewis bases in dichloromethane at 20 °C. Analysis with the linear free energy relationship log K_B =LA_B +LB_B allows equilibrium constants, K_B , to be calculated for any type of borane/Lewis base combination through the sum of two descriptors, one for Lewis acidity (LA_B ) and one for Lewis basicity (LB_B ). The resulting Lewis acidity/basicity scale is independent of fixed reference acids/bases and valid for various types of trivalent boron-centered Lewis acids. It is demonstrated that the newly developed Lewis acidity/basicity scale is easily extendable through linear relationships with quantum-chemically calculated or common physical-organic descriptors and known thermodynamic data (ΔH BF3 ). Furthermore, this experimental platform can be utilized for the rational development of borane-catalyzed reactions.

SUBMITTER: Mayer RJ 

PROVIDER: S-EPMC7985883 | biostudies-literature | 2021 Feb

REPOSITORIES: biostudies-literature