A series of polybrominated diphenylcarbenes (DPCs) are generated by irradiation of the corresponding precursor diazomethanes, and their reactivities are investigated by means of low-temperature spectroscopies as well as laser flash photolysis. Triplet bis (2, 4, 6- tribromophenyl) carbene was shown to decay by undergoing dimerization and to have a half- life of 1 s in a degassed benzene solution at room temperature, some 6 orders of ...