2, 6-Diazidobiphenylene was synthesized and photolyzed in frozen matrix. The resulting electron spin resonance spectrum showed the formation of 2, 6-biphenylenedinitrene as a quintet species with zero field splitting (zfs) parameters∣ D/hc∣= 0.260±0.002 cm− 1,∣ E/hc∣≤ 0.0005 cm− 1. The zfs parameters are in excellent accord with dipolar models for a quintet state produced by interaction between triplet state nitrene sites.