Tungsten Ligand-Based Sulfur-Atom-Transfer Catalysts: Synthesis, Characterization, Sustained Anaerobic Catalysis, and Mode of Aerial Deactivation

The synthesis, properties, X-ray structures, and catalytic sulfur-atom-transfer (SAT) reactions of W2(μ-S)­(μ-S2)­(dtc)2(dped)2 [1; dtc = S2CNR2 –, where R = Me, Et, iBu, and Bn; dped = S2C2Ph2 2–] and W2(μ-S)2(dtc)2(dped)2 (2) are reported. These complexes represent the oxidized (1) and reduced (2) forms of anaerobic SAT catalysts operating through the bidirectional, ligand-based half-reaction (μ-S)­(μ-S2) ↔ (μ-S)2 + S0. The catalysts are deactivated in air through the formation of catalytically inactive oxo complexes, (dtc)­WO­(μ-S)­(μ-dped)­W­(dtc)­(dped) (3), prompting us to recommend that group 6 SAT activity be assessed under strictly anaerobic conditions.