Synthesis of a Cp* Complex of Tungsten with Three Different Chalcogenido (O2−, S2−, and Se2−) Ligands

Oxygen, sulfur, and selenium all coordinate to the same tungsten atom in the mixed-chalcogenido complex [PPh4][Cp*W(O)(S)(Se)] (3; Cp*=C5Me5), which has been prepared by the reaction of [Cp*W(O)(S)(SR)] (R=Me (2 a), CH2Ph (2 b)) with Li2Se2 followed by cation exchange (see scheme). This unique mixed-chalcogenide complex is thermodynamically stable, and does not exhibit chalcogen-exchange reactions in solution.