Binuclear mercury (II) complexes of ambidentate sulfonium ylides in comparison with analogous phosphonium-based complexes; synthesis, characterization and a comprehensive theoretical study

The dehydrobromination reaction of a new sulfonium salt [(Me)2SCH2(O)C10H7]Br (1) with sodium hydroxide solution led to formation of sulfonium ylide (Me)2SCHC(O)C10H7 (2) which was used to synthesize three binuclear complexes [{(Me)2SCHC(O)C10H7}2HgX2]2 (X = Cl (3), Br (4) and I (5)). Characterization of all compounds was thoroughly performed by elemental analysis, IR, 1H and 13C NMR spectroscopic methods. Also the structure of complex (4) was characterized by X-ray crystalography methode. The structure of prepared complexes was also compared with analogous phosphonium complexes [{Ph3PCHC(O)C10H7}2HgX2]2 (X = Cl, Br and I) using DFT calculations with the M06/def2-SVP level of theory. Based on the theoretical studies of geometry-optimized bidentate structures, the interaction energy values, ΔEint, for C→M bonds in [{(Me)2SCHCOC10H7}HgX2]2 complexes are larger than those in [{Ph3PCHCOC10H7}HgX2]2 (X = Cl, Br and I) complexes. Obviously, in comparison to the phosphonium ylide, the sulfonium ylide forms a stronger bond with Hg2X4 (X = Cl, Br and I) fragments in aforementioned complexes.