Summary
Mixed-ligand complexes formed by reaction of Cu(ClO4)2 with 3-(2-pyridyl)-5,6-diphenyl-1,2,4-triazine (dppt) as primary ligand and 2,2′-bipyridine (bipy), 1,10-phenanthroline (phen), 2,9-dimethyl-1,10-phenanthroline (dmp), N,N-bis(pyrid-2-ylmethyl)amine (dipica), N,N-bis(benzimidazol-2-ylmethyl)amine (bba), 1,3-bis(2-benzimidazolyl)-2-thiapropane (bbms) and 1,5-bis(benzimidazolyl)-3-thiapentane (bbes) as the secondary ligands have been isolated. They are of the type [Cu(dppt)L](ClO4)2·nH2O, where n = 0 or 2. All complexes exhibit only one ligand field band and their cryogenic solution e.p.r. spectra are axial, with vmax and g ∥ values diagnostic of a square-based geometry. The spectral and redox data are consistent with facial coordination of the tridentate ligands. All the complexes exhibit a positive redox potential (versus n.h.e.). The weak σ-bonding of dppt, caused by the highly electron-withdrawing phenyl rings, the strong π-back bonding involving phen and dmp, and interligand repulsions appear to be responsible for the relatively positive CuII/CuI redox potentials.
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Murali, M., Palaniandavar, M. Mixed-ligand copper(II) complexes with positive redox potentials. Transition Met Chem 21, 142–148 (1996). https://doi.org/10.1007/BF00136544
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DOI: https://doi.org/10.1007/BF00136544