A Stable and Crystalline Nitrene

Photolysis of the arylazide MSFluindN3 (1) gave rise to the quantitative formation of arylnitrene MSFluindN (2), featuring a triplet ground state (MSFluind = dispiro[fluorene-9,3’-(1’,1’,7’,7’-tetramethyl-s-hydrindacen-4’-yl)-5’,9’’-fluorene]). Unlike all previously known arlynitrenes that decay within nanoseconds, 2 remains unchanged for a few days when stored under argon atmosphere at ambient conditions. The extraordinary life span permitted the full characterization of 2 by single crystal X-ray crystallography, EPR spectroscopy and SQUID magnetrometry. Besides the kinetic stabilization brought by the bulky MSFluind arly substituent, electron delocalization across the central aromatic ring contributed to the electron stabilization of 2.