metalthiolate

Metalthiolate refers to compounds in which a thiolate ligand, the deprotonated form of a thiol (RS−), binds to a metal center through sulfur. The resulting M–S bonds are a defining feature, giving rise to a wide range of mononuclear, dinuclear, and polynuclear species. Thiolate ligands are common in coordination chemistry and organometallic chemistry, particularly with transition metals such as iron, copper, nickel, palladium, platinum, and gold.

Coordination modes vary. Thiolates can bind terminally to a single metal, bridge between two metals, or occupy multiple sites in clusters. They stabilize diverse oxidation states and structural motifs, including discrete complexes like M(SR)n and organometallic clusters such as Fe2S2(SR)4 or AuSR-based nanoclusters. In gold chemistry, thiolate ligands are famous for protecting nanoparticle cores (for example, Au nanoclusters like Au25(SR)18), forming well-defined core–shell architectures.

Synthesis typically involves generation of thiolate in the presence of a metal source. This can be achieved by deprotonating thiols with a base to form RS− in situ, followed by reaction with a metal salt, or by ligand exchange with preformed metal-thiolate complexes. Conditions and ligands influence nuclearity, geometry, and electronic properties.

Applications span catalysis, materials science, and bioinorganic chemistry. Metal thiolates participate in catalytic cycles, serve as precursors to metal-sulfur clusters, and underpin self-assembled monolayers and thiolate-protected nanoparticles. In biology, metal–thiolate interactions are central to metalloproteins and iron-sulfur clusters, where cysteine residues coordinate metals via sulfur. Safety and handling depend on the specific metal and thiolate; many thiol-containing compounds have strong odors and varying toxicities.