Structures and Energetics of NI₃ and N₂ I₄

We have applied new methods for performing coupled-cluster calculations to small molecules containing iodine atoms; specifically, NI₃ and N₂ I₄ . Because NI₃ is known to be very reactive, attempts to measure its thermodynamic properties have been challenging at best. To date, N₂ I₄ has not been isolated, and our results suggest that its isolation will be just as challenging. We find that the ΔH_f (NI₃ )=+307.7 kJ mol^-1 and ΔH_f (N₂ I₄ )=+551.6 kJ mol^-1 , confirming that they are unstable with respect to their decomposition products N₂ and I₂ .