Determining inversion barriers in atropisomers - A tutorial for organic chemists

Abstract

Dynamic behavior is a fascinating property of natural and artificial systems and its understanding has significantly impacted the transformation of molecular interchanges into controlled molecular motion. In this tutorial, the key descriptors of enantiomeric stability are examined in-depth. Enantiomerization and racemization are discussed and differentiated on a fundamental level proposing a unified and distinct nomenclature. Their mathematical meanings and relations are described and deduced cohesively in the context of atropisomerization. The calculation of inversion barriers from thermodynamic and kinetic data is demonstrated and the interdependences between the latter are explained mathematically. Using current examples from our group, the determination of rate constants and the thermodynamic parameters is shown in a step-by-step manner using the most common techniques. The tutorial is concluded with aspects and considerations concerning statistical data analysis and error determination of measurements including a practical guide to Monte-Carlo simulations.