Palladium(II) Agostic Complex: Exchange of Aryl–Pd and Alkyl–Pd Bonds

Cyclopalladation of 2-tbutyl-6-(4-fluorophenyl)­pyridine with palladium acetate cleanly gives cyclometalated complex 3 with an aryl–Pd bond. Replacement of the acetates by chloride gives the monomeric species 4 with a crystal structure confirming the presence of an agostic interaction from the alkyl group. Reaction of 3 with Na­(acac) initially gives the monomeric acac complex 5 which maintains the aryl–Pd bond. Complex 5 shows fluxional behavior of the acac group, and this provides a pathway for its isomerization to complex 6 which has an alkyl–Pd bond; complex 6 was characterized crystallographically. Reaction of agostic 4 with triphenylphosphine gives an initial complex that maintains the aryl–Pd bond, but this complex isomerizes to crystallographically characterized 8 which has an alkyl–Pd bond.