Tricarbonylrhenium complexes from 2-pyridyl-1,2,3-triazole ligands bearing a 4-substituted phenyl arm: a combined experimental and theoretical study

Abstract

Three new pyridyltriazole ligands (named pyta) bearing a 4-substituted phenyl arm (nitro- (2a), chloro- (2b) or aminophenyl (2c) moiety) have been synthesized using a convenient click chemistry strategy. The corresponding tricarbonylrhenium complexes 3a, 3b and 3c were prepared and fully characterized by means of NMR, IR and mass spectrometry, as well as X-ray crystallography for two of them (3a and 3b). The direct connection of a 4-substituted phenyl arm at the N1 position of the triazolyl ring has a significant influence on the geometry of both, the ligands and their corresponding Re-complexes. The dominant structural feature of these complexes concerns the crystal cohesion. Slip-stacked π-π interactions between two molecules of the complex were observed for 3a and 3b probably resulting from the co-planarity of the organic framework. Furthermore, a combined experimental study and DFT calculations showed that the nature of the pendant arm (X = NO2, NH2 or Cl) could affect the electronic properties of the Re-complexes. If the chloro- or aminophenyl moieties unmodified the photo-physical properties of the complexes 3b and 3c, the presence of a nitrophenyl arm for the complex 3a quenched the luminescence, due to a high probability of non-radiative deactivation.

Rhenium Complexes Based on an N2O Tridentate Click Scaffold: From Synthesis, Structural and Theoretical Characterization to a Radiolabelling Study

“…Bifunctional chelator 11 with an amino arm was prepared by two different synthetic routes from compound 1 (Scheme ). The desired compound was prepared in two steps by using a well‐established procedure: a CuAAC reaction between 1 and freshly prepared 4‐azidonitrobenzene ( 8 ) in the presence of the classical catalytic system [copper(II) acetate monohydrate/sodium ascorbate] followed by catalytic hydrogenation using 10 % palladium on charcoal as the catalyst afforded 11 in 79 % yield. As an alternative, starting with 4‐azidoaniline ( 9 ), 11 was obtained in one step but with a lower yield than that of the two‐step procedure (60 % vs. 79 %).…”

“…Rhenium complexes [Re(CO) 3 (L)] (LH = 5 , 10 or 11 ) were synthesized through a substitution reaction, as reported previously . All the tricarbonylrhenium complexes were obtained in high yields (89–97 %) when the given chelator LH was treated with commercial precursor [Re(CO) 5 Cl] in the presence of a base in methanol at reflux overnight (Scheme ).…”

“…Intermediate Synthesis: Methyl azidoacetate, 2‐(prop‐2‐yn‐1‐ylamino)phenol ( 1 ), 2‐[( tert ‐butyldimethylsilyl)oxy]aniline ( 2 ), 1‐azido‐4‐nitrobenzene ( 8 ) and the rhenium precursor [Re(CO) 3 (H 2 O) 3 ]Br were synthesized according to literature protocols.…”

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

“…[58][59][60][61][62] In this respect, the relation between the energy adsorption band of the electronic spectra and metal-to-ligand charge transfer (MLCT) for all the complexes were modeled via DFT approaches.…”

“…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.…”