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 M^SFluindN₃(1), which gave rise to the quantitative formation of the arylnitrene M^SFluindN (2) (M^SFluind 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 of2by 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 M^SFluind aryl substituent, electron delocalization across the central aromatic ring contributes to the electron stabilization of2.

R₂BiOH (1) [R = 2-(Me₂NCH₂)C₆H₄] and (R₂Bi)₂O (2) are formed by hydrolysis of R₂BiCl with KOH. Single crystals of 2 were obtained by air oxidation of (R₂Bi)₂. The reaction of R₂BiCl and Na₂CO₃ leads to (R₂Bi)₂CO₃ (3). 3 is also formed by the absorption of CO₂ from the air in solutions of 1 or 2 in diethyl ether or toluene. (R₂Bi)₂S (4) is obtained from R₂BiCl and Na₂S or from (R₂Bi)₂ and S₈. Exchange reactions between R₂BiCl and KBr or NaI give R₂BiX [X = Br (5), I (6)]. The reaction of RBiCl₂ (7) with Na₂S and [W(CO)₅(THF)] gives cyclo-(RBiS)₂[W(CO)₅]₂ (8). cyclo-(R′BiS)₂ (9) [R′ = 2,6-(Me₂NCH₂)₂C₆H₃] is formed by reaction of R′BiCl₂ and Na₂S. The structures of 1–9 were determined by single-crystal X-ray diffraction.