Topological Analysis of the Laplacian Distributions in Hypervalent Halogen Bonding Complexes.

PERUCHENA, N. M.; DUARTE, D. J. R.; SOSA, G. L.

Porto Cesareo

Simposio; First International Symposium on Halogen Bonding; 2014

In this work, the analysis of the Laplacian distribution of the charge density was employed in the description of halogen bonds between the CO molecule as Lewis base and hypervalent halogen compounds as Lewis acids, it is Fn-X (with n= 1, 3, 5 and X= Cl, Br and I). Topologically, it is well know that the conventional halogen-bonding complexes result from the interaction between the ―lumps‖ localized onto valence shell charge concentration (VSCC) of electron-donor atom (C this case) and the charge density depletion zone localized onto the X halogen atom, in the σ-bond direction, (also known as σ-hole). However, in hypervalent halogen (as F5X) this depletion of charge density is not localized as a σ-hole. What is more, the charge density depletion region on the VSCC of the hypervalent halogen shows appearance of a belt around of the cap of charge concentration (see Figure 1). Figure 1: Envelops at L(r) = −¼∇ 2ρ(r) = -0.0125 au. Note that in FBr···CO and F3Br···CO complexes, the molecules are oriented so that the lumps in the VSCC of the carbon atom are aligned with the holes in the VSCC of the bromine atom. However, in F5Br···CO complex, the lumps in the VSCC of the carbon atom interacts with a belt of electronic charge depletion located around of a cap of charge concentration. In addition, the bond paths of ρ (r) are shown.