... The first covalent DA system to undergo the N–I transition is the metal-complex chain compound [Ru 2 (2,3,5,6-F 4 PhCO 2 ) 4 DMDCNQI]·2(p-xylene) (0, 2,3,5,6-F 4 PhCO 2 – = 2,3,5,6-tetrafluorobenzoate, DMDCNQI = 2,5-dimethyl-N,N′-dicyanoquinonediimine, Scheme ...