We study the order in which a strong laser field removes multiple electrons from a van der Waals (vdW) cluster. The N2Ar, with an equilibrium T-shaped geometry, contains both a covalent and a vdW bond and serves as a simple yet rich example. Interestingly, the fragmenting double and triple ionizations of N2Ar with vdW bond breaking are favored when the vdW bond is aligned along the laser field ...

Transition metal ions in aqueous solutions generally exist as complex ions in which water molecules, acting as Lewis bases, "coordinate" or bond with the small cation (which acts as a Lewis acid). The water molecules in these structures are known as ligands. Historically this kind of attachment has been called either a coordinate covalent bond or a dative bond. The distinguishing characteristic...

Transition metal ions in aqueous solutions generally exist as complex ions in which water molecules, acting as Lewis bases, "coordinate" or bond with the small cation (which acts as a Lewis acid). The water molecules in these structures are known as ligands. Historically this kind of attachment has been called either a coordinate covalent bond or a dative bond. The distinguishing characteristic...

The present contribution analyzes the special bonding situation of the [FAAF](-) anions (A = O, S, Se, Te), where the addition on an extra charge turns the covalent A-A bond of the neutral into a charge-shift (CS) bond. By means of theoretical calculations, we demonstrate that electrostatic interactions produced by negative point charges can transform the covalent A-A bond in the A2(+) cation i...

This Highlight presents an overview of the rapidly growing field of dynamic covalent polymers. This class of polymers combines intrinsic reversibility with the robustness of covalent bonds, thus enabling formation of mechanically stable, polymer-based materials that are responsive to external stimuli. It will be discussed how the inherent dynamic nature of the dynamic covalent bonds on the mole...

The NMR spin-spin coupling constants (SSCCs) across the H-bond in proteins are sensitive to the electronic structure of the H-bonded system, i.e., the N-H‚‚‚OdC group in proteins. The spin-spin coupling mechanism across the H-bond involves a strong electric field effect, steric exchange interactions, and some weak covalent effects (transfer of electronic charge). The electric field effect is re...

The efficacy of a mechanism-based enzyme inhibitor depends not only on the rate of covalent modification of the target enzyme, but also on the affinity with which the enzyme binds the inhibitor before covalent bond formation. Since proteinases have binding regions that extend many residues beyond the scissile peptide bond, specific and potent mechanism-based inhibitors of this class of enzyme c...

We describe the development of Lewis’s ideas concerning the chemical bond and in particular the concept of the electron pair bond and the octet rule. We show that the concept of the electron pair bond has endured to the present day and is now understood to be a consequence of the Pauli principle. In contrast the octet rule is now regarded as much less important than was originally generally bel...