Carbon-13 CIDNP in the reversible addition of pentafluorobenzoyloxy radicals to chlorobenzene

13C CIDNP observed during photolysis of perfluorobenzoyl peroxide in the presence of chlorobenzene provides evidence for the reversible formation of a σ-complex of the pentafluorobenzoyloxy-radical with chlorobenzene, predominantly via attack at the ortho and para positions.