Square‐Pyramidal Chalcogenide Tungsten Clusters with Pyrazole

This work presents the synthesis of two novel pentanuclear tungsten chalcogenide complexes, namely [{W 5 Q 5 (μ‐pz) 4 }(pzH) 5 ]Cl 2 (Q = S, Se). To obtain [{W 5 S 5 (μ‐pz) 4 }(pzH) 5 ]Cl 2 , W 6 Cl 12 is reacted with Na 2 S, S, and pyrazole in a sealed glass ampoule. The synthesis of [{W 5 Se 5 (μ‐pz) 4 }(pzH) 5 ]Cl 2 is conducted in two stages. The structure of the sulfide cluster complex is elucidated through single‐crystal X‐ray diffraction analysis. Furthermore, both compounds are characterized by nuclear magnetic resonance spectroscopy and mass spectrometry, and their redox properties are investigated by cyclic voltammetry. Both compounds exhibit two consecutive reversible or quasireversible one‐electron reductions, corresponding to the transition from the 14 VEC (valence electron count) to 15 VEC and 16 VEC forms, respectively.