Extending the Molecular Electron Density Theory

ended

Revealing why and how reactions take place is the essential goal for fundamental investigations of chemical reactivity. The breaking and forming of chemical bonds in a chemical reaction is directly associated with the depletion and accumulation of electron density between atoms. In the recently proposed Molecular Electron Density Theory (MEDT), the origin of chemical reactivity is deduced directly from the changes of electron density, as analysed by well-established quantum-chemical tools. This contrasts with typical approaches (e.g., molecular-orbital theory), where chemical reactivity is inferred, indirectly, from mathematical entities that are not directly associated with changes in electron density. Building on the new chemical insights obtained by the application of MEDT to pericyclic reactions and 1,3-dipolar cycloaddition reactions, the principle goals of this project are (a) to develop and extend MEDT to additional electron-density-based quantum chemical tools and more accurate types of computations and (b) to convince physical and organic chemists that MEDT is preferable to traditional methods for the rationalisation of chemical reactivity. To achieve the second goal, we will revisit traditional chemical concepts, many of which were proposed even before the development of modern quantum chemistry, and assess whether they are consistent with observed electron density changes. We will also explore applications of MEDT, both to traditional textbook reactions in organic chemistry and to the intricate reaction pathways associated with prebiotic chemistry, especially the prebiotic syntheses of imidazole, nucleotides, and other touchstone prebiotic molecules. By these means, we shall establish MEDT as a new paradigm for interpreting chemical reactivity, based on the experimentally observable electron density.