The calculated properties illustrated in Figs. and strongly imply the existence of conjugation between the diazirine group and the attached aromatic ring. As such, they suggest that the central carbon of the diazirine might best be described as being sp 2 -hybridized, rather than being assigned the sp -hybridization state that is typically ascribed to saturated systems, or the sp hybridization that is sometimes used to explain the properties of cyclopropanes. Recognizing that hybridization state strongly influences bond angle (or, put another way, that bond angle constitutes one of the central pieces of data upon which the theoretical construction of hybridization state is based), we calculated the optimized geometry for the parent diazirine (H 2 CN 2 ) and diaziridine (H 2 CN 2 H 2 ) molecules, as well as for trifluoromethyl phenyl diazirine. A series of control molecules Calculated conformational preferences (M06-2X/6-311+G(2df,2p)) for trifluoromethyl phenyl diazirine, and for the corresponding diaziridine.