Group 14 Central Atoms and Halogen Bonding in Different Dielectric Environments: How Germanium Outperforms Silicon.

The nature of halogen bonding under different dielectric conditions remains underexplored, especially for inorganic systems. The structural and energetic properties of model halogen bonded complexes (R3M−I—NH3 for R=H and F, and M=C, Si, and Ge) are examined computationally for relative permittivities between 1 and 109 using an implicit solvent model. We confirm and assess the exceptionally high maximum potentials at the sigma hole on I (Vs,max) in F3Ge−I relative to cases where M=C or Si. In particular, Ge far outperforms Si in mediating inductive effects. Linear relationships, typically with R2 >0.97, are identified between Vs,max, the full point charge on I in R3M−I, and the interaction energy, and optimized I—N distance in the complexes. An anomalous trend is identified in which, for each M, F3M−I—NH3 becomes less stable as the optimized I—N distance gets shorter in different dielectric environments; it is explained using the F−I—NH3 complex as a reference. [ABSTRACT FROM AUTHOR]