The geometrical parameters
and the bonding in [D···X···D]+halonium compounds, where D is a Lewis base with N as the
donor atom and X is Cl, Br, or I, have been investigated through a
combined structural and computational study. Cambridge Structural
Database (CSD) searches have revealed linear and symmetrical [D···X···D]+frameworks with neutral donors. By means of density functional
theory (DFT), molecular electrostatic potential (MEP), and energy
decomposition analyses (EDA) calculations, we have studied the effect
of various halogen atoms (X) on the [D···X···D]+framework, the effect of different nitrogen-donor groups
(D) attached to an iodonium cation (X = I), and the influence of the
electron density alteration on the [D···I···D]+halonium bond by variation of the R substituents at the N-donor
upon the symmetry, strength, and nature of the interaction. The physical
origin of the interaction arises from a subtle interplay between electrostatic
and orbital contributions (σ-hole bond). Interaction energies
as high as 45 kcal/mol suggest that halonium bonds can be exploited
for the development of novel halonium transfer agents, in asymmetric
halofunctionalization or as building blocks in supramolecular chemistry.