Photochromic and electrochromic properties of oxo-centred triruthenium compounds with a dithienylethene bis(phosphine) ligand

Abstract

The reaction of 1,2-bis(5-(diphenylphosphino)-2-methylthien-3-yl) cyclopentene (PPh₂-DTE-PPh₂) with the triruthenium cluster precursor [Ru₃O(OAc)₆(py)₂(CH₃OH)](PF₆) (1) gave monomeric or dimeric derivatives [Ru₃O(OAc)₆(py)₂{PPh₂-DTE-PPh₂}](PF₆) ([2]PF₆) and [{Ru₃O(OAc)₆(py)₂}₂{μ-PPh₂-DTE-PPh₂}](PF₆)₂ ([3]PF₆). Reduction of [2]⁺ and [3]²⁺ afforded one- or two-electron-reduced neutral products Ru₃O(OAc)₆(py)₂{PPh₂-DTE-PPh₂} (2) and {Ru₃O(OAc)₆(py)₂}₂{μ-PPh₂-DTE-PPh₂} (3), respectively. These triruthenium complexes show remarkable photochromism through photochemical ring-closing (UV light irradiation) and ring-opening (Vis light irradiation) processes as well as electrochromic properties through oxidation/reduction in the triruthenium cluster. Both the photochromic and electrochromic properties of 2 and 3 are highly reversible.