Role of halogen atoms in the formation of one-dimensional Cu(I) coordination polymers based on 2-amino-5-halopyrimidine

Abstract

The reactions of CuCl and CuBr with 2-amino-5-chloropyrimidine (L-Cl), 2-amino-5-bromopyrimidine (L-Br) and 2-amino-5-iodopyrimidine (L-I) in aqueous solutions of HCl and HBr afforded [CuCl2(HL-I) · H2O]n, 1, [CuBr2(HL-I) · H2O]n, 2, [CuCl2(HL-Br) · H2O]n, 3, [CuBr2(HL-Br) · H2O]n, 4, and [CuCl2(HL-Cl) · H2O)n, 5. Complexes 1–5 show 1D zigzag chains due to the zigzag arrangements of the bridging halide atoms. While the iodo atoms of the pyrimidyl rings in 1 and 2 are trans to the bridging halide anions and the Cu(I) ions are in a linear array, the chloro and bromo atoms of the pyrimidyl rings in 3–5 are cis to the bridging halide anions and the Cu(I) ions are in a zigzag fashion. The structural difference can most probably be ascribed to the identity of the halogen atoms. While the chloro and bromo atoms play the same role in the crystal structures, the iodo atom is distinct. X-ray crystallographic study and Hirshfeld surface analysis are invoked to investigate the structural differences.