Synthesis, Characterization and Reactivity Study of a New Penta-Coordinated Mn(II) Complex
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A penta-coordinated Mn(II) compound [dqpMnCl2] (1) (dqp = 2,6-di-(8-quinoline-yl)-pyridine) has been synthesized and its X-ray crystallographic structure is reported here. Magnetic susceptibility measurements confirmed a high-spin Mn(II) (S = 5/2) center in 1. The X-band EPR spectrum of 1 in dimethylformamide solution exhibits widely distributed transitions in the spectral range from 0 to 700 mT with particularly well-resolved hyperfine lines due to the 55Mn (I = 5/2) nucleus. The abundance of highly resolved transition lines in the spectrum facilitated the electron paramagnetic resonance spectral simulation which revealed large zero-field splitting and g-anisotropies. When dissolved, 1 exists in equilibrium with a hexa-coordinated species, the latter probably resulting from disassociation of one chlorido-ligand allowing ligation of two solvent molecules. The redox behavior of 1 was studied and was compared to that of a structural analog for which water oxidation in the presence of a chemical oxidant has been shown. The results from water oxidation trials of 1 are discussed.
KeywordsHyperfine Coupling Water Oxidation Mn4Ca Cluster Bulk Electrolysis Solid State Spectrum
The authors wish to thank Dr. Olof Johansson and Michael Jäger for providing the dqp-ligand. The authors would like to express their great gratitude to the financial support from the Swedish Energy Agency, the Knut and Alice Wallenberg Foundation, the EU/NEST Projects SOLAR-H (contract # 516510) and the EU/Energy project SOLAR-H2 (contract #2 12508).
- 18.G.M. Sheldrick, SHELXS97 and SHELXL97 (University of Göttingen, Göttingen, 1997)Google Scholar
- 20.J.R. Pilbrow, Transition Ion Electron Paramagnetic Resonance (Oxford University Press, New York, 1991)Google Scholar
- 21.F.E. Mabbs, D. Collison, Electron Paramagnetic Resonance of d Transition Metal Compounds (Studies in Inorganic Chemistry) (Elsevier, Amsterdam, 1992)Google Scholar
- 22.C. Baffert, M.N. Collomb, A. Deronzier, S. Kjaergaard-Knudsen, J.M. Latour, K.H. Lund, C.J. McKenzie, M. Mortensen, L. Nielsen, N. Thorup, Dalton Trans. 1765–1772 (2003)Google Scholar
- 26.W.C. Stalling, K.A. Pattridge, M.L. Ludwig, Superoxide and Superoxide Dismutase in Chemistry, Biology and Medicine (Elsevier, Amsterdam, 1986)Google Scholar
- 27.O. Kahn, Molecular Magnetism (Wiley-VCH, New York, 1993)Google Scholar
- 28.P. Kurz, G. Berggren, M.F. Anderlund, S. Styring, Dalton Trans. 4258–4261 (2007)Google Scholar