Synthesis of a stable crystalline nitrene.

Nitrenes are a highly reactive, yet fundamental, compound class. They possess a monovalent nitrogen atom and usually a short life span, typically in the nanosecond range. Here, we report on the synthesis of a stable nitrene by photolysis of the arylazide MFluindN (), which gave rise to the quantitative formation of the arylnitrene MFluindN () (MFluind is dispiro[fluorene-9,3'-(1',1',7',7'-tetramethyl-s-hydrindacen-4'-yl)-5',9''-fluorene]) that remains unchanged for at least 3 days when stored under argon atmosphere at room temperature. The extraordinary life span permitted the full characterization of by single-crystal x-ray crystallography, electron paramagnetic resonance spectroscopy, and superconducting quantum interference device magnetometry, which supported a triplet ground state. Theoretical simulations suggest that in addition to the kinetic stabilization conferred by the bulky MFluind aryl substituent, electron delocalization across the central aromatic ring contributes to the electron stabilization of .