[1,2,4]Triazolo[4,3-a]Pyridines as Bridging Ligands—Magnetism of Azole-Bridged Dinuclear Copper(II) Complexes Influenced by the Trigonal Distortion Parameter τ

Abstract

The dinuclear doubly azole-bridged copper(II) complexes [Cu(II)2(L)2(MeCN)4](ClO4)4·3.73MeCN·0.80H2O and [Cu(II)2(L)6](ClO4)4·solvent (solvent = 2MeCN·H2O; 2MeCN·2H2O; 1.5MeOH·3.5H2O) were prepared [L = 3-(6-methyl-2-pyridyl)-[1,2,4]triazolo[4,3-a]pyridine]. Structural characterizations revealed very different local geometries about the copper(II) ions, being trigonal bipyramidal for the former (τ = 0.76) and square pyramidal for the latter (τ = 0.07, 0.15, 0.07) complex. Magnetic measurements of bulk material [Cu(II)2(L)2(H2O)4](ClO4)4 and [Cu(II)2(L)6](ClO4)4·2H2O revealed antiferromagnetic coupling in both complexes, however, of very different strengths. Electron paramagnetic resonance (EPR) spectroscopy was applied to investigate magnetic properties of the complexes in detail. These experimental findings were supported by broken-symmetry DFT calculations. Systematic magneto-structural correlations are discussed.

Structure and antioxidant superoxide dismutase activity of copper(II) hydrazone complexes

“…Other 2and 2.212(2) Å) bond lengths in the square-pyramidal complex. These bond lengths and angles are in good agreement with that recently reported for analogous square-pyramidal Cu(II) species [62,[68][69][70][71][72]. In the outer sphere of complex the nitrate anion was found to be disordered.…”

1,4‐Piperazinium Hydrogen Sulfate {[H‐pi]HSO4} a Novel Di‐Cationic Ionic Liquid: Synthesis, Characterization and Its Applications as a Catalyst in Various Organic Transformations

“…For example, Cevipabulin (known as TTI‐237, an anti‐microtubule agent with potential antitumor activity), and Trapidil (an antiplatelet drug developed as a vasodilator and antiplatelet agent), are two examples of important drugs containing triazolo[4,3‐ a ]pyrimidine framework (Figure ). Furthermore, application as useful bridging ligands for the coordination to metals are another important application of imidazo[1,2‐ a ]pyrimidines and triazolo[4,3‐ a ]pyrimidines . The versatility of these compounds led to exploit various methods for the synthesis of them in which three‐component reaction of aldehydes, malononitrile and 2‐aminobenzimidazole and/or 3‐amino[1,2,4]triazole as amine sources, is a short‐route and time‐saving method.…”

2‐Amino‐5‐(2‐pyridyl)‐thiadiazole as Bidentate Ligand

“…[9][10][11][12][13][14][15][16][17][18][19][20][21] And especially the thiadiazole unit was found to form mononuclear transition metal complexes of iron(II), cobalt(II), nickel(II) and copper(II), [22] including iron(II) spin crossover complexes. [16,22,23] The results presented here have been obtained while studying the complexation behavior of 2-amino-5-(2-pyridyl)-1,3,4-thiadiazole (H 2 L). This molecule was first prepared in 1958 [24,25] the best of our knowledge has not been structurally characterized nor have its complexes been isolated.…”