Experimental and Theoretical Charge Density Analysis of a Bromoethyl Sulfonium Salt

Bromoethyl
sulfonium trifluoromethanesulfonate is a salt complex
in which a sulfur atom makes three covalent bonds. This molecule has
been proved to act as an efficient annulation reagent which results
in formation of synthetically challenging and pharmaceutically important
4-, 5-, 6-, and 7-membered heterocycles in excellent yields. The charge
density of the molecule was determined from both experimentally and
theoretically derived diffraction data. The stereochemistry and electron
density topology of the sulfonium group was analyzed. To understand
the chemical reactivity of the molecule, the electrostatic potential
difference between the two carbon atoms of the bromoethyl group was
investigated. It has been considered that the hydrogen atoms on the
carbon atom bound to sulfur are more acidic in character due to their
vicinity with the triply covalently bonded positively charged sulfur
atom. The electropositivity of the S-attached and Br-attached methylene
groups are compared in the experimental and theoretical charge densities
using topological atomic charges and electrostatic potential at the
molecular surface.