Photo-activated valence isomerization of hexamethyl(Dewar benzene)(HMDB) assisted by arene–iron(II) complexes: luminescence properties of [HMDB ⋯(η5-C5R5)Fe(η6-arene)]* adducts

Abstract

Hexamethyl(Dewar benzene)(HMDB) isomerizes to hexamethylbenzene (HMB) under light irradiation in the presence of stoicheiometric or catalytic amounts of the cationic complexes [(η⁵-C₅R₅)Fe(η⁶-arene)]⁺X^–, (R = H, Me; X = BF₄^–, PF₆^–), (1a–e) and (2), in dichloromethane solutions at 273 K; mixtures of HMDB and (1b–e) or (2) in dichloromethane exhibit a luminescence band at 530–540 nm probably due to formation of the corresponding exciplex.