X-ray photoelectron spectra of complexes with 1-(D-3-mercapto-2-methylpropionyl)-L-proline and Ni(II), Cd(II) and Cu(I): synthesis and LAXS study of Cu(I) derivative

Metal complexes of general formula Na2M(CAP)(2). xH(2)O (with M = Cd(II) or Ni(II), x = 7 and 4, respectively, CAP = 1-(D-3-mercapto-2-methylpropionyl )-L-proline) and NaCuCAP . 3H(2)O have been synthesized as amorphous compou nds and studied by means of X-ray photoelectron spectroscopy (XPS). Cu(I) d erivative has been studied by IR, XPS and large-angle X-ray scattering (LAX S). IR data and the chemical shift of core level signals suggest that CAP i s bonded to the metal via the sulphur atom and the carbonylic oxygen. LAXS data confirm this finding and are consistent with a tetrahedral configurati on around the copper ion. The CAP molecule is bonded through the sulphur an d the carbonylic oxygen and two water molecules complete the coordination a round the metal. The sodium ion exhibits a tetrahedral configuration and in teracts with the carboxylic group and two water molecules. One of these is bridging bonded between copper and sodium, No metal-nitrogen bonds are pres ent. (C) 2000 Elsevier Science B.V. All rights reserved.