A one-electron perspective on dative and ionic bonding.

The distinction between electron-sharing and dative bonding remains a matter of continued debate more than a century after Lewis's foundational contributions to chemical bonding. Here we show that part of the apparent dichotomy may arise from an overemphasis on electron pairs as the fundamental units of bonding. Using a combination of Generalized Valence Bond (GVB) theory, real-space descriptors (Laplacian of the electron density, delocalization indices, and IQA energy decomposition), electron distribution functions, and variational quantum Monte Carlo Born maxima, we find that many bonds traditionally considered either dative or ionic can be consistently interpreted within a peculiar single-electron bonding framework. In these interactions, one electron of the nominal bonding pair remains largely localized on one fragment, whereas its spin-paired companion delocalizes between fragments, providing a dominant contribution to bonding. We illustrate this motif in prototypical ionic, polar covalent, and donor-acceptor systems. While this perspective does not fully resolve the conceptual distinctions between dative and ionic bonding, it offers a coherent interpretation across different bonding regimes and suggests that the proposed kind of single-electron bonding may be rather common and chemically relevant.