Click-Triazole N2 Coordination to Transition-Metal Ions Is Assisted by a Pendant Pyridine Substituent

Abstract

We report that 1-(2-picolyl)-1,2,3-triazole (click triazole) forms stable complexes with transition-metal ions in which the coordination involves the triazole N2 nitrogen atom and the pendant 2-picolyl group. This is exemplified by model compound 1-(2-picolyl)-4-phenyl-1H-1,2,3-triazole (L(x)) and its complexes with transition-metal ions of Pt(II), Pd(II), Cu(II), Ru(II), and Ag(I). The coordination was investigated experimentally and theoretically. Ligand L(x) easily reacted at room temperature with cis-[PtCl(2)(DMSO)(2)], [Pd(CH(3)CN)(4)](BF(4))(2), CuCl(2), [RuCl(mu-Cl)(eta(6)-p-cymene)](2), and AgNO(3) to give stable chelates [PtCl(2)L(x)] (1), [Pd(L(x))(2)](BF(4))(2) (2), [CuCl(2)(L(x))(2)] (3), [RuCl(eta(6)-p-cymene)L(x)]OTf (4), and [Ag(2)(L(x))(2)(NO(3))(2)] (5), respectively, in 60-98% yield. The structures of 1-5 were unambiguously confirmed by NMR spectroscopy and single-crystal X-ray diffraction analysis. Density functional theory calculations were carried out in order to theoretically investigate the stabilization factors in 1-5. A comparison of the chelating properties of ligand L(x) was made with structurally similar and isomeric 1-(2-aminoethyl)-substituted 1,2,3-triazole (L(y)) and 4-(2-aminoethyl)-substituted 1,2,3-triazole (L(z)). The complexation affinity of L(x) was attributed to pi-back-donation from the metal to the pendant pyridine side arm, whereas the stability of the complexes involving L(y) and L(z) mainly originates from efficient pi-back-donation to the triazole ring.

A pyridyl-triazole ligand for ruthenium and iridium catalyzed CC and CO hydrogenations in water/organic solvent biphasic systems

“…It is worth remarking that both the 1 H and the 13 C NMR spectra are in good agreement with those reported by Kǒsmrlj and co-workers for the strictly related species [RuCl( 6 -p-cymene)(1b)]Cl (for the chemical structure of ligand 1b see Scheme 1) the structure of which has been determined by X-ray crystallography [32,33].…”

“…In fact, in the 1 H NMR spectrum (CD 3 OD, 298 K) of 2 both the H(1) doublet and the H(7) singlet are found significantly downfield with respect to the free ligand ( ı = 0.57 and 0.33 ppm, respectively) as found for other pyridyl-triazole ligands when chelating to a metal centre [23,31,32]. Definitive evidence for chelation of 1 at ruthenium comes from the AB spin pattern found for the methylene bridge protons.…”

Computational investigations of click-derived 1,2,3-triazoles as keystone ligands for complexation with transition metals: a review

“…past decades, 8,59,79,80,82,94,98,99 whereas the chelating behavior of donor-functionalized 3H-1,2,3,4-triaza-phosphole derivatives is still practically uncharted. [100][101][102] Clearly speaking, the click reaction between donor-functionalized azides and phosphaalkynes enables access to polydentate ligands, so that we can adjust the stereoelectronic properties based on the additional phosphorus heteroatom and the nature of the substituents.…”

“High-Throughput” Evaluation of Polymer-Supported Triazolic Appendages for Metallic Cations Extraction

“…We thus started to use the "click-chemistry" concept for polymer functionalization and especially copper (I)-catalyzed Huisgen's cycloaddition ("copper (I)-catalyzed azide/alkyne cycloaddition" or CuAAC) [24][25][26][27][28][29]. The use of CuAAC has the advantage to give a quick access of controlled substitutions onto the polymer by the use of its azided version and alkynes with various substituents [30][31][32][33][34][35]. This CuAAC is linking the azided polymer and the substituents bearing alkyne by forming the 1,4-triazole linkage.…”

“…The chelation can be a monoor multi-dentate mode due to the vicinity of other chelating entities and the flexible structure of the polymer chains. (Figure 1) [34,35]. The goal of this work was to try to find a faster method, using less polymer, for the evaluation of several metal cations complexation evaluation.…”