To test whether the higher stability of radical cis,cis-9 is only due to its increased preference for a closed conformation, or also influenced by differences in the electron affinities of 9 and 11, we computed the relevant anions of these species (see Figure in the Supporting Information for details). The substituted nitroxide cis,cis-9 displays an electron affinity of -52.1 kcal/mol, versus -54.6 kcal/mol for 11. Thus, the longer lifetime of cis,cis-9 relative to 11 may be due to both electronic and conformational effects. Computational studies into the other nitroxides are currently ongoing to identify relevant trends that govern their stability.