A Continuum from Halogen Bonds to Covalent Bonds: Where Do λ3 Iodanes Fit?

Using beryllium bonds to change halogen bonds from traditional to chlorine-shared to ion-pair bonds.

Ab initio MP2/aug'-cc-pVTZ calculations have been carried out to investigate the structures, binding energies, and bonding characteristics of binary complexes HFBe:FCl, R2Be:FCl, and FCl:N-base, and of ternary complexes HFBe:FCl:N-base and R2Be:FCl:N-base for R = H, F, Cl; N-base = NH3, NHCH2, NCH. Dramatic synergistic cooperative effects have been found between the Be···F beryllium bonds and t...

Covalent Bonds

A New Type of Halogen–Halogen Bonds

The interactions between the two CX3 groups in perhalogenated ethanes, X3C–CX3 are studied, with X3C–CX3 = H3C–CH3, F3C–CF3, F3C–CCl3, and Cl3C–CCl3. Utilising the recently developed method for revealing non-covalent interactions in molecular systems by Johnson et al. [1], a previously overlooked non-covalent interaction between halogens attached to opposite carbon atoms is unearthed. Further i...

Halogen bonds as orthogonal molecular interactions to hydrogen bonds.

Halogen bonds (X-bonds) are shown to be geometrically perpendicular to and energetically independent of hydrogen bonds (H-bonds) that share a common carbonyl oxygen acceptor. This orthogonal relationship is accommodated by the in-plane and out-of-plane electronegative potentials of the oxygen, which are differentially populated by H- and X-bonds. Furthermore, the local conformation of a peptide...

Asymmetric bifurcated halogen bonds.

Halogen bonding (XB) is being extensively explored for its potential use in advanced materials and drug design. Despite significant progress in describing this interaction by theoretical and experimental methods, the chemical nature remains somewhat elusive, and it seems to vary with the selected system. In this work we present a detailed DFT analysis of three-center asymmetric halogen bond (XB...