Browsing by Author "Bauer, Markus"

Transition metal nitrides/nitrenes are highly promising reagents for catalytic nitrogen atom transfer reactivity. They are typically prepared in situ upon optically induced N2‐elimination from azido precursors. A full exploitation of their catalytic potential, however, requires in‐depth knowledge of the primary photo‐induced processes and the structural/electronic factors mediating the N2‐loss with birth of the terminal metal‐nitrogen core. Using femtosecond infrared‐spectroscopy, we elucidate here the primary molecular‐level mechanisms responsible for the formation of a unique platinum(II) nitrene with a triplet ground state from a closed‐shell platinum(II) azide precursor. The spectroscopic data in combination with quantum‐chemical calculations provide compelling evidence that product formation requires the initial occupation of a singlet excited state with an anionic azide diradical ligand that is bound to a low‐spin d8‐configured PtII ion. Subsequent intersystem‐crossing generates the Pt‐bound triplet azide diradical, which smoothly evolves into the triplet nitrene via N2–loss in a near barrierless adiabatic dissociation. Our data highlight the importance of the productive, N2‐releasing state possessing azide ππ* character as a design principle for accessing efficient N‐atom‐transfer catalysts.