L→S2+←L Complexes (Sulfurones) with Unique Architecture: Synthesis, Crystal Structure and Quantum Chemical Analysis

Many innovative complexes with (NHC)→S (NHC is N-Heterocyclic Carbene) coordination bonds were theoretically designed and synthetically obtained in the past five years. Taking this as a clue, (NHC)→S2+←(NHC) systems were proposed as sulfurones. In this work, the synthesis and crystal structures of a few sulfurones have been reported. The unique (L→S) dative bond characteristics have been established by comparing their electronic character of sulfurones with that of species containing C=S=C bonds using Density functional theory (DFT). The experimental as well as the quantum chemical data clearly indicate the presence of L→S coordination interactions in sulfurones.