Author(s): Iakovidis A, Hadjiliadis N, Schollhorn H, ThewaltU, Trotscher G
The reactions of cis-Pt(NH3)2Cl2 with the amino acids of increasing aliphatic side chain glycine (gly), L-alanine (ala), 2-amino-butyric acid (2-abaH), L-norvaline (n-val) and L-valine (valH) were studied in aqueous solutions. Five new chelate complexes of the general formula cis-[Pt(NH3)2(am-ac)](NO3), with the amino acid coordinated through −NH2 and COO−, were isolated from these studies and characterized by elemental analysis, conductivity measurements, IR and 1H NMR spectra. Furthermore, the crystal structures of three of these chelates, namely the ones of gly (1), ala (2) and val (3) were determined by X-ray diffraction techniques. The crystals belonged to the space groups P21/n, P212121 and C2 with unit cell parameters a = 7.930(2), b = 17.583(3), c = 5.825(2) Å for 1; a = 13.097(2), b = 5.616(2), c = 12.704(2) Å for 2; a = 23.065(2), b = 5.926(2), c = 18.062(2) Å for 3. Their refinements were carried out to final R factors of 0.058, 0.063 and 0.069 for 1330, 1586 and 2266 reflections respectively. Treatment of the compounds with an equivalent amount of HCl acid produced the corresponding monocoordinated (−NH2) complexes of the formula cis-[Pt(NH3)2(am-acH)Cl](NO3) which were rarely isolated, but detected with 1H NMR spectra.