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Lewis Acidic Boranes, Lewis Bases, and Equilibrium Constants: A Reliable Scaffold for a Quantitative Lewis Acidity/Basicity Scale
Author(s) -
Mayer Robert J.,
Hampel Nathalie,
Ofial Armin R.
Publication year - 2021
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.202003916
Subject(s) - lewis acids and bases , chemistry , boranes , borane , equilibrium constant , boron , computational chemistry , catalysis , inorganic chemistry , organic chemistry
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 (Δ HBF3). Furthermore, this experimental platform can be utilized for the rational development of borane‐catalyzed reactions.