Photolysis of a High‐Spin Azidoiron(III) Complex Studied by Time‐Resolved Fourier‐Transform Infrared Spectroscopy

The laser‐flash photolysis of the high‐spin azidoiron(III) complex [FeIII(Me3Cyclam‐ac)(N3)]PF6 ([1]PF6) in liquid acetonitrile solution at room temperature was explored by time‐resolved Fourier‐transform infrared spectroscopy. Excitation of [1] at 480 and 266 nm induced a photoreduction of the metal center and generated [FeII(Me3Cyclam‐ac)(NCCH3)]+ ([2]) and azidyl radicals. Both photoproducts were detected independently through scavenging experiments. The metal‐containing fragment was quenched with carbon monoxide to generate an iron(II) carbonyl complex, whereas the nitrogen‐containing fragment was quenched with iodide to form azide anions. In the presence of N3−, the photoreduction created the elusive hexanitrogen radical anion N6.− as a transient byproduct. A closer look at photolysis: Time‐resolved infrared spectroscopy is used to explore the liquid‐phase photochemistry of the high‐spin ferric azide complex [FeIII(Me3Cyclam‐ac)(N3)]PF6. Excitation of the complex at 480 and 266 nm induced a photoreduction of the metal center and generated [FeII(Me3Cyclam‐ac)(NCCH3)]+ and azidyl radicals.