How the addition of atomic hydrogen to a multiple bond can be catalyzed by water molecules.

Observational data show complex organic molecules in the interstellar medium (ISM). Hydrogenation of small unsaturated carbon double bond could be one way for molecular complexification. It is important to understand how such reactivity occurs in the very cold and low-pressure ISM.

The NCIWEB Server: A Novel Implementation of the Noncovalent Interactions Index for Biomolecular Systems.

It is well-known that the activity and function of proteins is strictly correlated with their secondary, tertiary, and quaternary structures. Their biological role is regulated by their conformational flexibility and global fold, which, in turn, is largely governed by complex noncovalent interaction networks. Because of the large size of proteins, the analysis of their noncovalent interaction networks is challenging, but can provide insights into the energetics of conformational changes or protein-protein and protein-ligand interactions.

The "Inverted Bonds" Revisited: Analysis of "In Silico" Models and of [1.1.1]Propellane by Using Orbital Forces.

This article dwells on the nature of "inverted bonds", which refer to the σ interaction between two sp hybrids by their smaller lobes, and their presence in [1.1.1]propellane.

Analysis of Reaction Processes On the Basis of the Evolution of Dynamic Orbital Forces: Examples of Cycloadditions, S 2 Substitution, Nucleophilic Addition, and Hydrogen Transposition.

The derivative of the energy of a canonical molecular orbital (MO) [or dynamical orbital forces (DOFs)] with respect to a bond length provides a reliable index of the bonding/antibonding character of this MO on this bond. The DOFs of selected MOs as a function of the reaction coordinate were computed for a panel of model reaction mechanisms: [2+4] (Diels-Alder) cycloaddition, [2+2] cycloaddition, second-order nucleophilic substitution (S 2), nucleophilic addition to a carbonyl group, and [1,2] hydrogen transposition. The results highlight the nature of the reorganization of the main MOs and the stage of the reaction coordinate (RC) at which it occurs.

Topological reaction sites--very strong chalcogen bonds.

The analysis of interactions in complexes of S(CN)2, Se(CN)2, SFCl and SeFCl with F(-) and Cl(-) anions is performed here. The sulphur and selenium atoms act in these complexes as Lewis acid centres interacting with fluorine and chlorine anions. The arrangement of sub-units in complexes is in agreement with the σ-hole concept; particularly it is a result of contacts between positive and negative electrostatic potential sites.

Intramolecular hydrogen bonds: the QTAIM and ELF characteristics.

B3LYP/aug-cc-pVTZ calculations were performed on the species with intramolecular O-H···O hydrogen bonds. The Quantum Theory of Atoms in Molecules (QTAIM) and the Electron Localization Function (ELF) method were applied to analyze these interactions. Numerous relationships between ELF and QTAIM parameters were found.

Fast topological analysis of 2D and 3D grids of data: application to the atoms in molecule (AIM) and the electron localization function (ELF).

The topological analysis of grids of data is used for determination of surfaces or volumes around maxima. The volumes are then related to chemical information such as atoms or bonds, and can be used for integration of local properties such as electronic population. The problem of global connectivity is reversed into the question of local connectivity yielding a linear scaling partition algorithm.