Synthesis of mononuclear and dinuclear ruthenium(ii) tris(heteroleptic) complexes via photosubstitution in bis(carbonyl) precursors

Abstract

A novel, and quite general, approach for the preparation of tris(heteroleptic) ruthenium(II) complexes is reported. Using this method, which is based on photosubstitution of carbonyl ligands in precursors such as [Ru(bpy)(CO)₂Cl₂] and [Ru(bpy)(Me₂bpy)(CO)₂](PF₆)₂, mononuclear and dinuclear Ru(II) tris(heteroleptic) polypyridyl complexes containing the bridging ligands 3,5-bis(pyridin-2-yl)-1,2,4-triazole (Hbpt) and 3,5-bis(pyrazin-2-yl)-1,2,4-triazole (Hbpzt) have been prepared. The complexes obtained were purified by column chromatography and characterized by HPLC, mass spectrometry, ¹H NMR, absorption and emission spectroscopy and by electrochemical methods. The X-ray structures of the compounds [Ru(bpy)(Me₂bpy)(bpt)](PF₆)·0.5C₄H₁₀O [1·0.5C₄H₁₀O], [Ru(bpy)(Me₂bpy)(bpzt)](PF₆)·H₂O (2·H₂O) and [Ru(bpy)(Me₂bpy)(CH₃CN)₂](PF₆)₂·C₄H₁₀O (6·C₄H₁₀O) are reported. The synthesis and characterisation of the dinuclear analogues of 1 and 2, [{Ru(bpy)(Me₂bpy)}₂bpt](PF₆)₃·2H₂O (3) and [{Ru(bpy)(Me₂bpy)}₂bpzt](PF₆)₃ (4), are also described.