Solution study and 2-D layered structures of zinc(II) and cadmium(II) complexes with N-2-(6-amino-3,4-dihydro-3-methyl-5-nitroso-4-oxopyrimidinyl)-L-methionine as ligand

The solution study of the N-2-(6-amino-3,4-dihydro-3-methyl-5-nitroso-4-oxo pyrimidinyl)-L-methionine has revealed that it acts as a monoprotic acid in the pH range 2.5-9.5. In solution the complexes detected with Zn(II) and C d(II) at 1:1 and 1:4 metal-to-ligand molar ratios were the mononuclear spec ies [ZnL2], [CdL2] and [Cd(HL)](2+), with the ligand coordinating through t he carboxylate group in the two former and through the pyrimidine ring in t he later. From these, two layered complexes of Zn(II) and Cd(II) with HL we re obtained. ([Zn(mu -L)(2)]. 2H(2)O)(n), monoclinic, space group P2(1), a = 10.882(3), b = 7.473(2), c = 18.534(4) Angstrom, beta = 90.92(2)degrees, Z = 2; ([Cd(mu -L)(2)]. 3H(2)O)(n), triclinic, space group P1, a = 7.615(2) , b = 10.427(2), c = 11.129(2) Angstrom, alpha = 86.29(3), beta = 78.87(3), gamma = 71.13(3)degrees, Z = 1. The structures of both complexes are very similar except for the coordination numbers of five and seven for Zn(II) an d Cd(II), respectively. These facts point out the versatility of this famil y of N-pyrimidine amino acids as ligands, as well as the importance of the crystallization processes in obtaining supramolecular compounds. (C) 2000 E lsevier Science S.A. All rights reserved.