Simple and effective synthesis of pentamethylcyclopentadienyl oxo-peroxo and dioxo tungsten acetylide complexes

The pentamethylcyclopentadienyl tungsten carbonyl acetylide complexes (C5Me5)W(CO)3(CCR), (1) R = Ph, CH2OMe, Prn and C(Me) = CH2, reacted with an acidic solution of hydrogen peroxide at room temperature, giving the oxo-peroxo acetylide complexes (C5Me5)W(O)(O2)(CCR) (2) in good yields. Upon treatment with triphenylphosphine the complexes (2) lost one oxygen atom to afford the corresponding dioxo complexes (C5Me5)W(O)2(CCR) (3). These oxo-peroxo and dioxo complexes were characterized by spectroscopic methods and, for (C5Me5)W(O)2(CCPh) (3a), was further identified by single crystal X-ray diffraction study.