Local Electron Densities and Functional Groups in Quantum Chemistry

Abstract

The connections between the quantum chemical concept of local electron densities and the traditional concept of functional groups of organic chemistry are explored. The Density Domain criterion of functional groups and the Additive Fuzzy Density Fragmentation (AFDF) method are the tools for the construction of representative quantum chemical models for both local electron densities and functional groups. The applications of the method of fuzzy electron density partitioning of molecular electron density clouds to the description of the local fuzzy density contributions of functional groups are explored. The constraints implied by the recently proven “Holographic Electron Density Theorem” are discussed, with special emphasis on the predictability of differences in the activity of functional groups of a given type located within different molecular environments. The special role of symmetry and symmetry deficiency are discussed, and the deviations from local symmetry, as a diagnostic tool for the assessment of the reactivity of functional groups are explored.