The effect of pH and complexation of amino acid functionality on the redox chemistry of methionine and X-ray structure of [Co(en)2(L-Met)](ClO4)2.H2O.
Anodic oxidation of methionine under different pH conditions is reported. The results are compared with the oxidation process when the glycinic terminus of methionine is coordinated with Co(III). Synthesis of [Co(en)2(L-Met)](ClO4)2, [Co(trien)(L-Met)](CF3SO3)2, and [Co(trien)(OSO2CF3)2]CF3SO3 is reported where L-methionine, en = ethylenediamine, trien = triethylenetetraamine. The triflato complex ([Co(trien)(OSO2CF3)2]CF3SO3) can serve as a starting material for synthesizing a variety of complexes. The x-ray structure of [Co(en)2(L-Met)](CIO4)2.H2O is also presented The complex crystallizes in space group P21 of the monoclinic system with two independent molecules in the crystallographic asymmetric unit. The unit cell dimensions are a = 9.582 (2) A, b = 11.554 (2) A, c = 19.988 (6) A, and beta = 98.85 (2) degrees. The two molecular units are related by a pseudo-center of symmetry. The electrochemical data presented here suggest a major role of the neighboring group and pH in defining the ease of oxidation of methionine.
Sanaullah
Department of Chemistry, University of Kansas, Lawrence, 66045-0046.
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D003035:Cobalt / Q000737:chemistry; D018360:Crystallography, X-Ray; D004563:Electrochemistry; D006863:Hydrogen-Ion Concentration; D008715:Methionine / Q000737:chemistry*; D008958:Models, Molecular; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000737:chemistry*; D010084:Oxidation-Reduction
D009942:Organometallic Compounds; D003035:Cobalt; D008715:Methionine