Synthesis, Magnetic and Spectral Properties of Some Metal(II) Complexes of Mercaptoacetic and 3-Mercaptopropionic Acid Derivatives of Vitamin B₁

Abstract

(4′-Amino-2′-methyl-5′-pyrimidinylmethylthio) acetic acid, Hamrapta, and the propionic acid analogue, Hammptp, and their copper(II), cobalt(II), zinc(II), palladium(II) and platinum(II) complexes have been synthesized. The pKa values of the acids (at 25°C) are 2.76 (Hammpta) and 2.74 (Hammptp). The complexes were characterized by microanalyses, IR and electronic spectra, conductivity and magnetic susceptibility measurements. While the zinc(II), palladium(II) and platinum(II) complexes exhibit tetrahedral and square-planar geometries, the copper(II) and cobalt(II) complexes exhibit a variety of geometries. One of the copper(II) complexes, [Cu(ammptp)ClH₂0], and one of the cobalt(II) complexes, [Co(Hammpta)₂Cl₂], are magnetically concentrated. [Co(Hammpta)₂Cl₂] is presumed to be low-spin octahedral or square-planar (μ = 2.18 B.M.), whereas the cobalt(II) complexes of Hammptp/ammptp⁻ are more prone to being tetrahedral.