Structural diversity in the self-assembly of Ag(I) complexes containing 2-amino-5-halopyrimidine

A series of Ag(I) complexes containing the 2-amino-5-halopyrimidine ligands have been synthesized and their structures characterized by X-ray crystallography. The isomorphous complexes Ag(L-Cl)2(CF3SO3) (L-Cl = 2-amino-5-chloropyrimidine), 1, and Ag(L-Br)2(CF3SO3) (L-Br = 2-amino-5-bromopyrimidine), 2, are mononuclear, while [Ag(L-Br)(CF3SO3)]6·6C4H10O, 3, and [Ag(L-I)(CF3SO3)]6 (L-I = 2-amino-5-iodopyrimidine), 4, show cyclic self-assembly of six Ag(Ι) atoms and six L-X ligands, resulting in 24-membered metallocycles. The complex [Ag(L-I)(CF3SO3)]∞, 5, forms 1D zigzag chains which are linked through C–I⋯Ag and Ag⋯O interactions to form a 3D structure. The tetranuclear complexes [Ag(L-X)(NO3)]4 [X = Cl, 6; Br, 7] form 16-membered metallocycles, while [Ag(L-X)(ClO4)]∞ [X = Cl, 8; Br, 9] exhibit helical chains. The different structure of 5 from 1 and 2 appears to be due to the stronger nucleophilic character of the iodine atom. In these complexes, the relatively smaller NO3− anions lead to the formation of tetranuclear metallocycles and the larger CF3SO3− anions support the hexanuclear metallocycles, whereas the ClO4− anions induce the helical chains.

Graphical abstractThe isomorphous complexes Ag(L-Cl)2(CF3SO3) (L-Cl = 2-amino-5-chloropyrimidine), 1, and Ag(L-Br)2(CF3SO3) (L-Br = 2-amino-5-bromopyrimidine), 2, are mononuclear, while [Ag(L-Br)(CF3SO3)]6·6C4H10O, 3, and [Ag(L-I)(CF3SO3)]6 (L-I = 2-amino-5-iodopyrimidine), 4, show a cyclic self-assembly of six Ag(Ι) atoms and six L-X ligands, resulting in 24-membered metallocycles. The complex [Ag(L-I)(CF3SO3)]∞, 5, forms 1D zigzag chains and the iodine atoms of the pyrimidyl rings coordinate to the silver atoms through C–I⋯Ag and Ag⋯O interactions, resulting in a 3D structure. The tetranuclear complexes [Ag(L-X)(NO3)]4 [X = Cl, 6; Br, 7] form 16-membered metallocycles, while [Ag(L-X)(ClO4)]∞ [X = Cl, 8; Br, 9] form helical chains. The different structure of 5 from 1 and 2 appears to be due to the stronger nucleophilic character of the iodine atom. In these complexes, the relatively smaller NO3− anions lead to the formation of tetranuclear metallocycles and the larger CF3SO3− anions support hexanuclear metallocycles, whereas the ClO4− anions induce helical chains.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► We report nine Ag(I) complexes containing the 2-amino-5-haloropyrimidine ligands. ► We examine the roles of halogen atom and anion in the structural types. ► Formation of strong Ag⋯I interaction is found for the iodo ligand. ► The size of the anion is important in determining the structural type.