Five-coordinate ZnII, NiII, and CuIIcomplexes containing pentadentate N3O2Schiff base ligands [1A]2-and [1B]2-have been synthesized and characterized. X-ray crystallographic studies reveal five coordinate structures in which each metal ion is bound by two imine N-donors, two phenolate O-donors, and a single amine N-donor. Electron paramagnetic resonance (EPR) spectroscopic studies suggest that the N3O2coordination spheres of [Cu(1A)] and [Cu(1B)] are retained in CH2Cl2solution and solid-state superconducting quantum interference device (SQUID) magnetometric studies confirm that [Ni(1A)] and [Ni(1B)] adopt high spin (S = 1) configurations. Each complex exhibits two reversible oxidation processes between +0.05 and +0.64 V vs [Fc]+/[Fc]. The products of one-and two-electron oxidations have been studied by UV/vis spectroelectrochemistry and by EPR spectroscopy which confirm that each oxidation process for the ZnIIand CuIIcomplexes is ligand-based with sequential formation of mono-and bis-phenoxyl radical species. In contrast, the one-electron oxidation of the NiIIcomplexes generates NiIIIproducts. This assignment is supported by spectroelectrochemical and EPR spectroscopic studies, density functional theory (DFT) calculations, and the single crystal X-ray structure of [Ni(1A)][BF4] which contains Ni in a five-coordinate distorted trigonal bipyramidal geometry. © 2013 American Chemical Society
Franks, M., Gadzhieva, A., Ghandhi, L., Murrell, D., Blake, A., Davies, E., et al. (2013). Five coordinate M(II)-diphenolate [M = Zn(II), Ni(II), and Cu(II)] Schiff base complexes exhibiting metal-and ligand-based redox chemistry. INORGANIC CHEMISTRY, 52(2), 660-670 [10.1021/ic301731w].
Five coordinate M(II)-diphenolate [M = Zn(II), Ni(II), and Cu(II)] Schiff base complexes exhibiting metal-and ligand-based redox chemistry
Moro, Fabrizio;
2013
Abstract
Five-coordinate ZnII, NiII, and CuIIcomplexes containing pentadentate N3O2Schiff base ligands [1A]2-and [1B]2-have been synthesized and characterized. X-ray crystallographic studies reveal five coordinate structures in which each metal ion is bound by two imine N-donors, two phenolate O-donors, and a single amine N-donor. Electron paramagnetic resonance (EPR) spectroscopic studies suggest that the N3O2coordination spheres of [Cu(1A)] and [Cu(1B)] are retained in CH2Cl2solution and solid-state superconducting quantum interference device (SQUID) magnetometric studies confirm that [Ni(1A)] and [Ni(1B)] adopt high spin (S = 1) configurations. Each complex exhibits two reversible oxidation processes between +0.05 and +0.64 V vs [Fc]+/[Fc]. The products of one-and two-electron oxidations have been studied by UV/vis spectroelectrochemistry and by EPR spectroscopy which confirm that each oxidation process for the ZnIIand CuIIcomplexes is ligand-based with sequential formation of mono-and bis-phenoxyl radical species. In contrast, the one-electron oxidation of the NiIIcomplexes generates NiIIIproducts. This assignment is supported by spectroelectrochemical and EPR spectroscopic studies, density functional theory (DFT) calculations, and the single crystal X-ray structure of [Ni(1A)][BF4] which contains Ni in a five-coordinate distorted trigonal bipyramidal geometry. © 2013 American Chemical SocietyI documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.