The electronic structures of diruthenium complexes containing an oligo(phenylene ethynylene) bridging ligand, and some related molecular structures

Abstract

The complexes [{Cp′(L₂)Ru}CCC₆H₄CCC₆H₂(OMe)₂CCC₆H₄CC{Ru(L₂)Cp′}](L₂ = (PPh₃)₂, Cp′ = Cp; L₂ = dppe, Cp′ = Cp*) in which the metal centres are bridged by an oligomeric phenylene ethynylene (OPE) ligand have been prepared and the electronic structure of these representative ruthenium-capped OPEs investigated using a combination of electrochemical, UV-vis-NIR and IR spectroelectrochemical methods, and DFT-based calculations. The diruthenium complexes are oxidised to the thermodynamically stable dications [Cp′Ru(L₂)CCC₆H₄CCC₆H₂(OMe)₂CCC₆H₄CCRu(L₂)Cp′]²⁺, which on the basis of the spectroelectrochemical and computational results can be described in terms of two non-interacting Ru(CCAr)(L₂)Cp′ moieties. X-ray structures of the oligophenyleneethynylene HCCC₆H₄CCC₆H₂(OMe)₂CCC₆H₄CCH, the bis(gold) complex Ph₃PAuCCC₆H₄CCC₆H₂(OMe)₂CCC₆H₄CCAuPPh₃ and the precursor 1-ethynyl-4-(trimethylsilylethynyl)benzene are also reported.