Metal complexes of sulphur-nitrogen chelating agents. I. 2-aminocyclo-pentene-l-dithiocarboxylic acid complexes of Ni(II), Pd(II) and Pt(II)

The Ni(II), Pd(II) and Pt(II) chelates of 2-amino- cyclopentene-l-dithiocarboxylic acid (ACDA) are described. With each metal ions, two differently colored products having identical composition M(ACDA)2 are obtained when reactions are carried out with the acid itself and its ammonium salt. PMR spectra of ACDA indicates strong hydrogen bonding between one amino proton and thiocarbonyl sulphur atom. The nature of bonding in the complexes have been investigated from their i.r, pmr and electronic spectra, magnetic moment, thermal analysis and X-ray diffraction data. In all the chelates bonding with metal ions occur through amino nitrogen and deprotonated thiolsulphur. The stability constant of Ni-ACDA complex has been evaluated spectrophotometrically. Ni(ACDA)2 forms a 1:2 adduct with pyridine. The color difference in the chelates probably arises due to geometrical isomerism