Intermediacy of Radicals in Rearrangement and Decomposition of Metal-Alkyl Species: Relevance to Metal-Mediated Polymerization of Polar Vinyl Monomers

Theneutralcompound[2,3-bis(2,6-diisopropylphenylimino)-butane]Pd(CH2CH2CH2C02Me)(X) (X = Cl, Br) undergoes "reverse" chain walking to fonn [2,3-bis(2,6-diisopropylphenylimino)-butane]Pd(CH(C02Me)CH2CH3)(X) through a conventional β-hydrogen elimination/readdition pathway. However, reversible Pd-alkyl bond homolysis occurs for both alkyl complexes, and the resultant radicals can initiate the polymerization of acrylates.