The Azo(Azoxy) Functionality as a π2 Component in Photo (2 + 2)Cycloadditions. “syn”‐ and “anti”‐3,4‐Diazatricyclo(4.2.2.22,5)dodeca‐3,7‐diene, Syntheses, Photolyses, X‐Ray Structure Analysis, and PE Spectra.

The propensity of the NN bond to undergo photo [2 + 2] cycloadditions has been further explored. In the specifically designed 1,5-azo/enes 1–3, no [2 + 2] cycloaddition has been observed upon either direct or sensitized excitation with light of various wave lengths at temperatures down to 77 K, in line with expectations based on X-ray (1: d = 2.71 A, ω = 129°) and PE measurements (1: I1 = 8.00, I2 = 9.05 eV; 2; I1 = 8.00, I2 = 9.25eV). The steric/stereoelectronic demands for the participation of the NN bond in pericyclic reactions are clearly more stringent than those for the CC bond.