Tuning the halogen–hydride interaction: the role of halogen and metal environments

Abstract

The tunability of halogen–hydride interactions was investigated by examining various substituents in the halogen donor as well as in the halogen acceptor units. For this purpose, we performed a systematic study on a series of dimeric complexes modelled as RX···HMY. The properties of these halogen–hydride interactions are modulated by variation of R (Cl, CN), X (Cl, Br, I), M (Be, Mg, Zn), and Y (H, CH3, C6H5) groups. It is found that some substituents have dramatic effects on the strength of the halogen–hydride bonds, leading to interactions that can be up to 100% stronger. The results indicate that the withdrawing effect of the R group and the electronegativity of the metal are the most influential factors that can change the interaction strength. Accordingly, among 54 studied complexes, the strongest interactions have been observed in the complexes in which M = Mg. Furthermore, we note that the redistribution of the electron charge due to the complex formation leads to decrease in the s-character of the X-orbital, which is in line with Bent's rule.For the complexes analysed here, various relationships between energetic and natural bond orbital parameters have been presented. Our results, allow the prediction of halogen–hydride interaction using different substituents, in order to tune and optimise ligand–protein interactions in the search for drug candidates.