Halogen‐bridged Cationic Complexes of the Type [{CpM(CO)3}2X]SbF6 (M = Mo,W; X = Cl,I), [{CpW(CO)2Cl2}2Cl]SbCl6, and the Trichloride CpW(CO)2Cl3

The reaction of CpMo(CO)₃X (X = Cl, I) with SbF₅ in toluene leads to the cationic, halogen bridged compounds {CpMo(CO)₃}₂X]SbF₆ ( 1 , 2 ). CpW(CO)₃Cl reacts with SbF₅ to yield {CpW(CO)₃}₂Cl]SbF₆ ( 3 ), whereas with SbCl₅, the oxidative substitution product {CpW(CO)₂Cl₂}₂Cl]SbCl₆ ( 4 ) is formed, which decomposes in solution to yield the trichloride CpW(CO)₂Cl₃ ( 5 ). The strong Lewis acid SbF₅ separates the halide from CpM(CO)₃X (M = Mo, W), and the resulting cationic fragment “CpM(CO)₃⁺” reacts with a further CpM(CO)₃X forming a halonium bridge ( 1 – 3 ). The exclusive formation of SbF₆^– can be explained by the oxidizing power of SbF₅. The IR, MS and NMR spectra of the compounds 1 – 5 as well as the X‐ray structure analysis of 5 are reported and discussed.