Synthetic, Spectroscopic and X-Ray Crystallographic Studies of Bivalent Metal Complexes with Amino Acids Having a Thiazolidine Ring. I. Properties of Bivalent Metal Complexes with (S)-4-Thiazolidinecarboxylic Acid and the Structure of Chloro((S)-4-thiazolidinecarboxylato)((S)-thiazolidinium-4-carboxylate)zinc(II)

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Abstract
Complexes of five bivalent metals with (S)-4-thiazolidinecarboxylic acid((Remark: Graphics omitted.)) have been prepared by three methods and characterized by means of infrared absorption, reflection spectra, magnetic susceptibility, thermal analysis, powder X-ray patterns, and single crystal X-ray diffraction. Two types of complexes were found. The first type[A] included ML2·nH2O (M=Co(II), Ni(II), Cu(II), Zn(II), Cd(II); L=(S)-4-thiazolidinecarboxylate anion) and ZnClL(HL) was the second type[B]. In A-type complexes, the ligand coordinates to the metal with a nitrogen atom and an oxygen atom. From the results of single-crystal X-ray diffraction studies, the second type-B ZnClL(HL) was found to be orthorhombic, with the space group P212121; a=9.719(2), b=22.194(4), c=5.8537(5) Å, U=1262.6(4) Å3, Z=4, Dm=1.91 Mg m−3, Dx=1.93 Mg m−3, and μ(Mo K α)=25.3 cm−1. Block-diagonal least-squares refinements have led to a final R value of 0.045. The zinc atom is penta-coordinated, being ligated with one carboxylate oxygen atom of (S)thiazolidinium-4-carboxylate, which has a zwitter ion structure, two carboxylato oxygen atoms and one nitrogen atom of (S)-4-thiazolidinecarboxylate anion, and a chloride atom. The structure comprises onedimensional polymers by the carboxylate oxygen atom of this anion-type ligand. The plane extends in the direction of c-axis. In neither the A- nor the B-type complexes does the ligand coordinate to a metal with a sulfur atom.