METAL CHELATES OF BIOLOGICALLY IMPORTANT COMPOUNDS .I. COMPLEXES OF DL-ETHIONINE AND S-METHYL-L-CYSTEINE

Complexes of DL-ethionine, CH3CH2SCH2CH2CH(NH2)COOH (ethH), and S-methyl-L-cysteine, CH3SCH2CH(NH2)-COOH (SmcH), have been prepared with manganese(II), cobalt(II), nickel(II), copper(II), zinc(II), palladium(II), platinum(II), cadmium(II), and mercury(II). The infrared spectra of the amino acids and of the metal complexes were measured in the range 4000-200 cm-1. The diffuse reflectance spectra of the cobalt, nickel, and copper complexes were measured in the range 25,000-7000 cm-1. Spectral and magnetic data indicate that the complexes are of four types, as follows, (a) ML2 (L = eth, Smc; M = Mn, Co, Ni, Cu, Zn, Cd) complexes are polymeric in the solid state with carboxyl bridges. The metal atom is six-coordinate and the amino acid is bound to one metal atom via the nitrogen and one oxygen and to another metal atom via the second oxygen. (b) M(LH)X2 (M = Pd, Pt; X = Cl, Br) complexes in which the amino acid is bound to the four-coordinate metal atom via the nitrogen and sulfur atoms only, (c) [Hg(ethH)2] (ClO4)2•H2O in which ethionine is possibly bound via the nitrogen only. (d) [AgCu(Smc)2]NO3 in which the amino acid residue is coordinated to the copper via nitrogen and oxygen and to silver via the sulfur atom. © 1968, American Chemical Society. All rights reserved.