Catalytic Sulfur-Atom Transfer Enabled by a Bis(disulfide) Titanium Complex

Multi-electron processes are key steps in the activation and valorization of small molecules. Due to titanium's electropositivity and the limited accessibility of low-valent precursors, multi-electron transformations and their application in atom-transfer reactions involving this element remain comparatively underdeveloped. Herein, we report a novel four-electron transformation from a Ti(IV) complex which enabled the formation of a rare titanium bis(disulfide) (Ti(S₂)₂) in a spiropentane motif. The fast and selective formation of this unique sulfur-rich complex was leveraged for the catalytic synthesis of isothiocyanates from the corresponding isonitriles. Notably, this reaction is highly efficient even at ambient temperatures and tolerates oxygen-containing functional groups, marking an advance over noble-metal catalyzed methods. Detailed mechanistic studies including reaction kinetics and quantum chemical calculations provide insights into the sulfur-atom transfer process and highlight the role of non-covalent interactions. Overall, these results represent a new approach in the development of multi-electron processes and atom-transfer catalysis with group IV metals.