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-oxopyrimidinyl)-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 Cd(II) at 1:1 and 1:4 metal-to-ligand molar ratios were the mononuclear species [ZnL2], [CdL2] and [Cd(HL)]2+, with the ligand coordinating through the carboxylate group in the two former and through the pyrimidine ring in the later. From these, two layered complexes of Zn(II) and Cd(II) with HL were obtained. {[Zn(μ-L)2]·2H2O}n, monoclinic, space group P21, a=10.882(3), b=7.473(2), c=18.534(4) Å, β=90.92(2)°, Z=2; {[Cd(μ-L)2]·3H2O}n, triclinic, space group P1, a=7.615(2), b=10.427(2), c=11.129(2) Å, α=86.29(3), β=78.87(3), γ=71.13(3)°, Z=1. The structures of both complexes are very similar except for the coordination numbers of five and seven for Zn(II) and Cd(II), respectively. These facts point out the versatility of this family of N-pyrimidine amino acids as ligands, as well as the importance of the crystallization processes in obtaining supramolecular compounds.