The Pd(I)鈭扨d(I) dimer [(FPNP)Pd鈭抅2 reacts with O2 upon exposure to light to produce either the superoxide (FPNP)PdO2 or the peroxide [(FPNP)PdO鈭抅2, which exist in equilibrium with free O2. Both complexes contain square-planar Pd(II) centers. The unpaired electron density in (FPNP)PdO2 is localized on the superoxide ligand.