Anions-Directed Metal-Mediated Assemblies of Coordination Polymers Based on the Bis(4,4′-bis-1,2,4-triazole) Ligand

Abstract

Eight coordination polymers, {[Cu(btr)2(H2O)2](BF4)2·2H2O}n (1), {[Cu5(btr)10(SCN)6(BF4)4]·5H2O}n (2), {[Cu(btr)2(SCN)2]·2H2O}n (3), {[Cu(btr)2(NO3)2]·H2O}n (4), {[Cu(btr)3](ClO4)2}n (5), {[Cd(btr)3](ClO4)2}n (6), {[Cd3(btr)8(H2O)2](BF4)6}n (7), and {[Cd3(btr)8(N(CN)2)2](BF4)4}n (8), were obtained from the corresponding metal salts with bis(4,4′-bis-1,2,4-triazole) (btr), and their structures were fully characterized. X-ray diffraction analyses revealed that compounds 1 and 2 were analogous, and 2 can be viewed as SCN− or BF4− anions replacing the coordinated water molecules in 1, exhibiting the two-dimensional (2D) meso coordination networks. 2 and 3 were isolated from the same crystallization, and 3 crystallized in a chiral space group P212121 with one-dimensional (1D) left-handed [Cu(btr)]∞ helical chains. When the BF4− anions were replaced by NO3− and ClO4− anions, completely different three-dimensional (3D) coordination polymers 4 and 5 were isolated, respectively; btr exhibited two bridging fashions at the same time in 4, connecting with the Cu(II) ions to give an unusual 3D network. Compound 4 is the first example of the μ3- and μ2-btr simultaneity in a single system in triazole-metal complexes. Compound 5 showed the α-polonium-like structure. When the metal center changed, a novel 3D compound 6 was obtained, which had the same coordination numbers for metal centers and the same space group but significantly different topology for coordination networks when compared with 5. Compounds 7 and 8 were 3D microporous metal-organic frameworks, which had the analogous structural features, including the tetranuclear metallocycles. The variety of dimensionalities based on the tuning of different anions and metal centers were discussed in detail. Variable-temperature magnetic susceptibility studies on the powder samples of 1−5 reveal the overall antiferromagnetic behavior in copper(II) compounds.