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

Abstract

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 (R3 M-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 F3 Ge-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 R3 M-I, and the interaction energy, and optimized I-N distance in the complexes. An anomalous trend is identified in which, for each M, F3 M-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.