Synthesis and Study of Carbenium-based Lewis Adducts that can access their Inner and Outer Forms

Texas A&M University, College Station TX

Investigators

Abstract

With support of the Chemical Mechanism, Function, and Properties Program of the Division of Chemistry, Professor François Gabbaï of the Department of Chemistry at Texas A&M University is investigating the ability of specific types of acid-base complexes to interconvert between two forms: namely, an inner form where the two components are bonded in a traditional sense and a more loosely held outer form that resembles an early stage in bond-forming processes. Studying these complexes can support a better fundamental understanding of chemical reactions and bonds. In addition to these objectives, this project aims to leverage this phenomenon for the discovery of next-generation catalysts, including photocatalysts. This multifaceted project will support catalyst development, produce knowledge in physical organic and inorganic chemistry, and contribute to the education and training of future scientists. Encounter complexes, also referred to as outer complexes, are typically intermediates invoked in various reactions, including Lewis acid-base adduct formation. This project will specifically target adducts of Lewis acidic carbenium ions that can isomerize between their datively bound inner form and their more elusive outer form, where the donor-acceptor interaction is non-covalent. By tethering the Lewis-opposite functionalities, the work will show how the nature of the carbenium unit, the donor properties of the Lewis base, and the backbone structure can be used to adjust the respective energies of the inner and outer forms, which is a prerequisite for dynamic inner/outer isomerism. The project will also explore how such a phenomenon may be harnessed for the reversible masking of reactive carbenium ions and for their possible use in photoredox catalysis. Another aim will employ this inner/outer isomerism as a tool to adjust the redox properties of the main group functionality acting as the Lewis base, with the objective of increasing two-electron redox cycling at chalcogen and pnictogen centers. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.