PHOTOGENERATION OF REACTIVE TITANIUM AND ZIRCONIUM SPECIES: A CIDNP STUDY

Article abstract of DOI:10.1016/S0022-328X(00)93589-7

Chemically induced dynamic nuclear polarization (CIDNP) studies of the photolytically initiated reactions of Cp'2Ti(CH3)2 (Cp' = methylcyclopentadienyl) and Cp2Zr(CH3)2 (Cp = cyclopentadienyl) have revealed that homolysis of the metal-methyl bond takes place, followed by a rapid recombination.The metal radical is shown to be one of the partners in the polarizing radical pair.Only very fast scavengers such as nitroxides, dioxygen and thiophenol can compete with the recombination reaction.Dimethylzirconocene undergoes a photochemically-initiated ethylene insertion reaction in which the olefin is inserted into the zirconium-methyl bond via an unprecedented radical process.