Synthesis of a stable crystalline nitrene.

Nitrenes are a highly reactive, yet fundamental compound class. They possess a mono-valent 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 M S FluindN 3 ( 1 ), which gave rise to the quantitative formation of the arylnitrene M S FluindN ( 2 ) (M S Fluind = 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 2 by single crystal x-ray crystallography, EPR spectroscopy and SQUID magnetometry, which supported a triplet ground state. Theoretical simulations suggest in addition to the kinetic stabilization conferred by the bulky M S Fluind aryl substituent, that electron delocalization across the central aromatic ring contributes to the electron stabilization of 2 .