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Abstract

A new series of Co(II) complexes of the type CoLX2 , where Lis a tetra-dentate ligand 8,8'-bis(aminomethyl)-2,2'-biquinoline  and X= SCN, BF4, I or NO3,  have been synthesized and characterized. The complexes have magnetic moments in the range typical of a low-spin d7 Co(II) center. The interaction of these Co(II) complexes with dioxygen was studied by E.S.R. spectroscopy. A dicobalt(III) peroxo-bridged complex was formed in DMF solution, associated with the formation of an E.S.R.-silent solution compatible with the formation of low-spin d6 Co(III) species. Similar behavior was also observed for the interaction of these Co(II) complexes with dioxygen in the presence of ancillary ligands such as pyridine and 2-methylimidazole. The dioxygen complexes proved successful as oxygen carrier oxidation catalysts for tripehnylphosphine and 2,6-bis(t-butyl)phenol.

 

 

Keywords

Biquinoline Cobalt(II) Dioxygen interaction E.S.R.

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References

  1. Murray, L.J., Dinca, M., Yano, J., Chavan, S., Bordiga, S., Brown, C.M. and Long, J.R. Highly-selective and reversible O2 binding in Cr3(1,3,5-benzenetricarboxylate)2. J. Am. Chem. Soc., 2010, 132(23), 7856-7857.
  2. Sun, Y., Chen, K., Jia, L. and Li, H. Toward understanding macrocycle specificity of iron on the dioxygen-binding ability: a theoretical study. Phys. Chem. Chem. Phys., 2011, 13(30), 13800-13808.
  3. Henrici‐Olivé, G. and Olive, S. Activation of molecular oxygen. Angew. Chem. Int. Ed., 1974, 13(1), 29-38.
  4. Sheldon, R.A. and Kochi, J.K., Chapter 4, Activation of Molecular Oxygen by Metal Complexes, In Metal-catalyzed Oxidations of Organic Compounds, p 71-119, ISBN 9780126393804, Academic Press, New York,1981.
  5. Sheldon, R.A., Metal-catalyzed Oxidations of Organic Compounds: Mechanistic Principles and Synthetic Methodology including Biochemical Processes. Elsevier, 2012.
  6. Buckingham, D.A., and Clark, C.R. In Comprehensive Coordination Chemistry, (Eds.) Wilkinson, G., Gillard, R.D. and McCleverty, J.A. Pergamon Press, Oxford, p 749-750, 1987.
  7. Tiné, M.R. Cobalt complexes in aqueous solutions as dioxygen carriers. Coord. Chem. Rev., 2012, 256(1), 316-327.
  8. Shahabadi, N., Kashanian, S. and Darabi, F. DNA binding and DNA cleavage studies of a water soluble cobalt(II) complex containing dinitrogen Schiff base ligand: The effect of metal on the mode of binding. Euro. J. Med. Chem., 2010, 45(9), 4239-4245.
  9. Calligaris, M., Nardin, G., Randaccio, L. and Ripamonti, A. Structural aspects of the synthetic oxygen-carrier NN′-ethylenebis-(salicylideneiminato) cobalt(II): structure of the addition compound with oxygen containing dimethylformamide. J. Chem. Soc. A: Inorg., Phys., Theo., 1970, 1069-1074.
  10. Floriani, C. and Calderazzo, F. Oxygen adducts of Schiff's base complexes of cobalt prepared in solution. J. Chem. Soc. A: Inorg., Phys., Theo., 1969, 946-953.
  11. Coleman, W.M. and Taylor, L.T. Dioxygen reactivity-structure correlations in manganese(II) complexes. Coord. Chem. Rev., 1980, 32(1), 1-31.
  12. Crumbliss, A.L. and Basolo, F. Monomeric cobalt-oxygen complexes. Science, 1969, 164(3884), 1168-1170.
  13. Calligaris, M., Nardin, G., Randaccio, L. and Tauzher, G. The structure of the 1:1 addition compound of molecular oxygen with NN′-ethylenebis(acetylacetoneiminato) cobalt(II) monopyridinate, Inorg. Nuc. Chem. Lett., 1973, 9(4), 419-422.
  14. Rodley, G.A. and Robinson, W.T. Structure of a monomeric oxygen-carrying complex, Nature, 1972, 235, 438.
  15. Chung, L.Y., Constable, E.C., Lewis, J., Raithby, P.R. and Kaye, P.T. Transition metal complexes of substituted 2,2′-biquinolines. Part 1. The crystal and molecular structures of [8,8′-bis(aminomethyl)-2,2′-biquinoline] dichloromanganese(II) and [8,8′-bis(aminomethyl)-2,2′-biquinoline] chlorocopper(II) chloride. J. Chem. Soc. Dalton Trans., 1988, (8), 2121-2125.
  16. McGarvey, B.R. and Carlin, R.L. Transition Metal Chemistry. Vol. 3, Marcel Dekker, New York, p 129-130.
  17. Figgis, B.N. and Lewis, J. The magnetic properties of transition metal complexes, Prog. Inorg. Chem., 1964, 6, 37-239.
  18. Hoffman, B.M., Diemente, D.L. and Basolo, F. Electron paramagnetic resonance studies of some cobalt(II) Schiff base compounds and their monomeric oxygen adducts. J. Am. Chem. Soc., 1970, 92(1), 61-65.