Color change of redox-active organometallic dithienylethene complexes by photochemical and redox processes

Abstract

Photochromic dithienylethene (DTE) derivatives, DTE–MCpL 2 {M = Fe, Ru; Cp = η 5-cyclopentadienyl; L 2 = (CO) 2, (CO)PPh 3, dppe (dppe = Ph 2PCH 2CH 2PPh 2)}, with a directly σ-bonded, redox-active organometallic attachment have been prepared and their response to photo- and electrochemical stimuli has been investigated. It turns out that the color of the organometallic derivatives can be controlled not only by photochromic processes but also by one-electron redox processes. The Ru complexes 1 Ru and 2 Ru exhibit reversible photochromism in a manner similar to organic DTE derivatives, with ring closing and ring opening triggered by UV and visible-light irradiation, respectively. Their photochromic behavior is critically dependent on both of the central metal and ligands. One-electron oxidation of the Fe complex 3 Fe gives the corresponding radical cationic species with a visible absorption.