1200124-91-9Relevant academic research and scientific papers
The redox series [Ru(bpy)2(L)]n, n = +3, +2, +1, 0, with L = bipyridine, click derived pyridyl-triazole or bis-triazole: A combined structural, electrochemical, spectroelectrochemical and DFT investigation
Hohloch, Stephan,Schweinfurth, David,Sommer, Michael G.,Weisser, Fritz,Deibel, Naina,Ehret, Fabian,Sarkar, Biprajit
, p. 4437 - 4450 (2014/03/21)
The compounds [Ru(bpy)2(L1)](ClO4) 2 (1(ClO4)2), [Ru(bpy)2(L 2)](ClO4)2 (2(ClO4)2), [Ru(bpy)2(L3)](ClO4)2 (3(ClO 4)2), [Ru(bpy)2(L4)](ClO 4)2 (4(ClO4)2), [Ru(bpy) 2(L5)](ClO4)2 (5(ClO 4)2), and [Ru(bpy)2(L6)](ClO 4)26(ClO4)2 (bpy = 2,2′-bipyridine, L1 = 1-(4-isopropyl-phenyl)-4-(2-pyridyl)-1,2, 3-triazole, L2 = 1-(4-butoxy-phenyl)-4-(2-pyridyl)-1,2,3-triazole, L3 = 1-(2-trifluoromethyl-phenyl)-4-(2-pyridyl)-1,2,3-triazole, L4 = 4,4′-bis-{1-(2,6-diisopropyl-phenyl)}-1,2,3-triazole, L5 = 4,4′-bis-{(1-phenyl)}-1,2,3-triazole, L6 = 4,4′-bis-{1-(2-trifluoromethyl-phenyl)}-1,2,3-triazole) were synthesized from [Ru(bpy)2(EtOH)2](ClO4)2 and the corresponding click -derived pyridyl-triazole or bis-triazole ligands, and characterized by 1H-NMR spectroscopy, elemental analysis, mass spectrometry and X-ray crystallography. Structural analysis showed a distorted octahedral coordination environment about the Ru(ii) centers, and shorter Ru-N(triazole) bond distances compared to Ru-N(pyridine) distances in complexes of mixed-donor ligands. All the complexes were subjected to cyclic voltammetric studies, and the results were compared to the well-known [Ru(bpy)3]2+ compound. The oxidation and reduction potentials were found to be largely uninfluenced by ligand changes, with all the investigated complexes showing their oxidation and reduction steps at rather similar potentials. A combined UV-vis-NIR and EPR spectroelectrochemical investigation, together with DFT calculations, was used to determine the site of electron transfer in these complexes. These results provided insights into their electronic structures in the various investigated redox states, showed subtle differences in the spectroscopic signatures of these complexes despite their similar electrochemical properties, and provided clues to the unperturbed redox potentials in these complexes with respect to ligand substitutions. The reduced forms of the complexes display structured absorption bands in the NIR region. Additionally, we also present new synthetic routes for the ligands presented here using Cu-abnormal carbene catalysts.
New 1,2,3-triazole ligands through click reactions and their palladium and platinum complexes
Schweinfurth, David,Pattacini, Roberto,Strobel, Sabine,Sarkar, Biprajit
experimental part, p. 9291 - 9297 (2010/02/16)
The new ligands, 1-(4-isopropyl phenyl)-4-(2-pyridyl)-1,2,3-triazole, 1 and 1-(mesityl)-4-(2-pyridyl)-1,2,3-triazole, 2 were prepared by the reactions of the respective azides with 2-ethynylpyridine following the "click method". These ligands together with the reported ligands 1-(phenyl)-4-(2-pyridyl)-1,2,3-triazole, 3 and 1-(benzyl)-4-(2-pyridyl)-1,2,3- triazole, 4 were reacted with palladium and platinum precursors to give mononuclear cis-dichloropalladium and platinum complexes containing the triazole ligands. Structural characterisation of the free ligand 3 shows that the central N-N bond in the triazole ring has double bond character and hence is best described as an "azo-like" N-N double bond. The pyridine ring in 3 has an almost "anti" conformation with respect to the central triazole ring. The metal centers bind to the ligands through the pyridine N and a triazole N atom. The metal-N(triazole) distances are shorter than the metal-N(pyridine) distances. Cyclic voltammograms of the ligands show reduction processes that appear at extreme negative potentials. Coordination of metal centers induces huge anodic shifts of the reduction potentials due to σ-polarisation by the metal centers. UV/Vis spectra of the ligands and complexes are also discussed. The properties of such chelating triazole ligands towards palladium and platinum centers is being compared and contrasted to the widely used 2,2′-bipyridine ligand.
