Anion-directed self-assembly of Cu(II) coordination compounds with tetrazole-1-acetic acid: syntheses in ionic liquids and crystal structures

Reaction of tetrazole-1-acetic acid (1-Htza) with a Cu(n) salt in ionic liquids with different anions, [BMIM]X (BMIM = 1-butyl-3-methylimidazolium; X = Br-, BF4-, NTf2- (NTf2- = bis((trifluoromethyl)sulfonyl)amide)), afforded five Cu(II) coordination compounds, [Cu-2(1-tza)(4)]Br center dot H3O center dot 1/3H(2)O (1), [Cu-2(1-tza)(4)]BF4 center dot H3O center dot H2O (2), [Cu(mu(2)-Cl)(1-tza)(1-Htza)(H2O)]center dot 0.5H(2)O (3), [CuCl(mu(2)-Cl)(1-Htza)(2)(H2O)]center dot H2O (4), and [CuCl2(1-Htza)(2)]center dot H2O (5). Single-crystal X-ray diffraction analyses reveal that 1-5 display various structures, and the 1-tza(-) ligand exhibits diverse coordination modes. Compounds 1 and 2 possess higher dimensional structures (a 2-D neutral Kagome topology network for 1 and a 3-D lvt-type topology framework for 2) with fully deprotonated 1-tza(-) ligands. Compounds 3-5 display lower dimensional structures (1-D, 1-D and O-D for 3, 4 and 5, respectively) with partly or fully protonated 1-Htza. The anions of ionic liquids have significant influences on the final molecular architectures, which arise from different water miscibility of ionic liquids.