Halogen⋯Halogen Interactions: Nature, Directionality and Applications.

Halogen⋯halogen interaction is a highly debated and important topic in crystal engineering and supramolecular chemistry. There are controversies about the nature and geometry of these interactions. F, Cl, Br and I are the four halogens involved in these interactions.

Bending properties in the 4-halobenzonitrile crystals and C-halogen...N[triple-bond]C halogen bonds.

The single crystal of 4-iodobenzonitrile (CHIN) is brittle, whereas those of 4-bromobenzonitrile (CHBrN) and one of the two forms of 4-chlorobenzonitrile (CHClN) are compliant in nature. The chloro crystal exhibits elastic bending, but in spite of having stronger halogen bonds, the bromo crystal exhibits plastic bending. Crystal structures have been analyzed to understand the different bending properties of these three crystals.

The Effects of Electronegativity of X and Hybridization of C on the X-C⋅⋅⋅O Interactions: A Statistical Analysis on Tetrel Bonding.

Cone and distance-cone corrected statistical analyses have been performed on X-C⋅⋅⋅O (X=H, B, C, N, O and F; the C atom is sp and sp hybridized) tetrel bonds. The sp -C and sp -C prefer to form the interactions through σ-hole (∠XCO≈180°) and π-hole (∠XCO≈90°), respectively. With the increase in electronegativity of X, the preference for the particular angles of the respective geometries increases and the C⋅⋅⋅O distance becomes shorter.