Synthesis, Characterisation and Ligand Properties of Novel Bi‐1,2,3‐triazole Ligands

Three 1,1′‐disubstituted 4,4′‐bi‐1 H ‐1,2,3‐triazols [R‐bta; R = Bn ( 1 ), Ph ( 2 ), CH 2 COOH ( 3 )] have been synthesised as bidentate, nitrogen‐based ligands by a Cu I ‐catalysed “click” reaction between 1,3‐butadiyne and organic azides. Their ligand properties were investigated by preparation of the complexes [Ru II (R‐bta) 3 ]Cl 2 [R = Bn ( 4 ), Ph ( 5 ), CH 2 COOH ( 6 )], [(Bn‐bta)Cu I (DPEPhos)] ( 7 ) [DPEPhos = bis{2‐(diphenylphosphanyl)phenyl} ether] and [(Bn‐bta)Re I (CO) 3 Cl] ( 8 ) following standard reaction procedures. All compounds were analysed by elemental analysis, mass spectrometry and NMR, IR, UV/Vis and luminescence spectroscopy. In addition, the molecular structures of 1 – 4 , 7 , and 8 have been determined by X‐ray crystallography. In all complexes the Bn‐bta acts as a bidentate ligand with structural features comparable to the analogous 2,2′‐bipyridine complexes. In their electronic absorption spectra the Ru II and Re I complexes exhibit a lowest energy band at around 300 nm, which is substantially higher in energy than in analogous complexes with bpy ligands. All R‐bta ligands yield complexes that are not luminescent in solution or in the solid state, which makes these ligands particularly suited for use as spectator ligands. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)