A synthetic cycle for H2/CO activation and allene synthesis using recyclable zirconium complexes.

The zirconium complexes supported by the anisole-bridged bis(phenoxide) ligands serve as an easily recycled auxiliary for converting H2 and CO into allene and hexamethyldisiloxane under mild conditions. Hydrogenolysis of the zirconium benzyl complexes followed by treatment with CO led to formation of oxo-bridged complexes and allene. Deoxygenation of the resulting oxo-bridged complexes with trimethylsilyltrifluoromethanesulfonate and trimethylsilyl chloride and subsequent treatment with benzylmagnesium chloride re-formed the starting benzyl complexes.