The tuning effect of 2-amino-4,6-dipyridylpyrimidine isomers on the structural dimensionalities and motifs of copper(I) cyanide complexes

Four novel copper(I) cyanide complexes of three isomeric oligopyridine ligands, namely 2-amino-4,6-bis(2-pyridyl)pyrimidine (L¹), 2-amino-4-(2-pyridyl)-6-(4-pyridyl)pyrimidine (L2), 2-amino-4-(2-pyridyl)-6-(3- pyridyl)pyrirnidine (L³) have been hydrothermally synthesized. These complexes have one- and two-dimensional structures, as determined by single-crystal X-ray diffraction. The structural dimensionalities and motifs of complexes 1-4 are directed by the coordination modes of the ligands. Thus, L¹ acts as a bis-chelating ligand in complex 1 to join the adjacent 1D (CuCN)_n chains into a two-dimensional corrugated layer. Complexes 2 and 4 both consist of one-dimensional zigzag chains where the ligands (L ² for complex 2 and L³ for complex 4) occupy the terminal positions and N⋯NH₂ hydrogen bonds play an important role in the assembly of the supramolecular network. Complex 3 (another product isolated from the L³-Cu-CN reaction system) is a two-dimensional network in which L³ acts as a bridging ligand and the cyanide groups exhibit both μ₂ and μ₃ linking modes. Further investigation shows that the thermal stability of complexes 1-4 is in the order 1 > 3 > 2 > 4.