The dramatic differences in conformational preference and bond angles observed for diaziridines and diazirines clearly support a change in hybridization state of the central carbon, as the N-N single bond is changed to an N=N double bond. This is distinct from what happens in moving from cyclopropane to cyclopropene (see Fig. ), where the bond angles around the non-doubly bonded carbon remain relatively constant. We contend based upon the data shown here that the diazirine motif (at least when embedded within a trifluoromethyl aryl diazirine functional group) is best described as being connected through an sp 2 -hybridized carbon atom, which thereby supports conjugation to an attached aromatic ring.