Thiol-functionalized 1,2,4-triazolium salt as carbene ligand precursor

► Synthesis of a chelating NHC ligand with unprotected thiol moiety. ► Oxidative C-S bond formation between triazolium and thiol by DMSO solvent. ► Preparation and solid-state structures of several transition metal complexes. ► Cross-coupling by palladium thiolato catalyst. ► Correlation of metal carbene bond lengths, back-bonding strength and NMR chemical shifts.