The synthesis, properties, X-ray structures, and catalytic sulfur-atom-transfer (SAT) reactions of W-2(mu-S)(mu-S-2)(dtc)(2)(dped)(2) [1; dtc = S2CNR2-, where R = Me, Et, iBu, and Bn; dped = S2C2Ph22-] and W-2(mu-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 (mu-S)(mu-S-2) <-> (mu-S)(2) + S-0. The catalysts are deactivated in air through the formation of catalytically inactive oxo complexes, (dtc)WO(mu-S)(mu-dped)W(dtc)(dped) (3), prompting us to recommend that group 6 SAT activity be assessed under strictly anaerobic conditions.