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

Abstract

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(CF 3SO 3) ( L- Cl = 2-amino-5-chloropyrimidine), 1, and Ag( L- Br) 2(CF 3SO 3) ( L- Br = 2-amino-5-bromopyrimidine), 2, are mononuclear, while [Ag( L- Br)(CF 3SO 3)] 6·6C 4H 10O, 3, and [Ag( L- I)(CF 3SO 3)] 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)(CF 3SO 3)] ∞, 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)(NO 3)] 4 [X = Cl, 6; Br, 7] form 16-membered metallocycles, while [Ag( L- X)(ClO 4)] ∞ [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 NO 3 − anions lead to the formation of tetranuclear metallocycles and the larger CF 3SO 3 − anions support the hexanuclear metallocycles, whereas the ClO 4 − anions induce the helical chains.