Synthesis and Characterization of Azidobipyridyl Ruthenium Complexes and Their “Click” Chemistry Derivatives

Abstract

The ligand 4‐azido‐2,2′‐bipyridyl (1) has been used to prepare 1,2,3‐triazole‐substituted ligands through copper‐catalyzed alkyne/azide cycloaddition (CuAAC or “click” chemistry) with phenylacetylene, ethynylferrocene and 2‐ethynylpyridine to yield 4‐(4‐phenyl‐1,2,3‐triazol‐1‐yl)‐2,2′‐bipyridyl (2a), 4‐(4‐ferrocenyl‐1,2,3‐triazol‐1‐yl)‐2,2′‐bipyridyl (2b) and 4‐[4‐(pyridyl‐2‐yl)‐1,2,3‐triazol‐1‐yl]‐2,2′‐bipyridyl (2c). Complexes of the form [Ru(p‐cymene)(Cl)(L)]PF6 (3, L = 1; 4a, L = 2a; 4b, L = 2b) were then prepared and characterized. We also report the synthesis of the complex of the analogous ligand 4,4′‐bisazido‐2,2′‐bipyridyl (1′), [Ru(p‐cymene)(Cl)(1′)]PF6 (3′). Complexes 4a and 4b were also prepared by an alternative route, whereby 3 undergoes CuAAC coupling with phenylacetylene and ethynylferrocene respectively. Complexes prepared with ligands that are pre‐assembled or “clicked” at the metal show identical 1H NMR spectra. CuAAC coupling of 3 and 2‐ethynylpyridine results in the formation of the complex [Ru(p‐cymene)(Cl)(2c)]PF6 (4c), which contains a coordinatively vacant pyridyltriazole moiety. The reaction of [Ru(p‐cymene)(Cl)2]2 with pre‐assembled 2c results in the formation of the dinuclear complex [{Ru(p‐cymene)(Cl)}2(2c)]·2PF6 (5), which incorporates ruthenium atoms at both bipyridyl and pyridyltriazole binding domains. The 1H NMR spectrum of the complex shows two signals for the triazole ring proton as well as duplicate signals for other protons of the bridging ligand, which indicates that 5 is produced as a mixture of diastereoisomers. The complex [{Ru(p‐cymene)Cl}2{di‐4‐([1‐{2,2′‐bipyrid‐4‐yl}triazol‐4‐yl]methyl)ether}][PF6]2 (7) was also prepared through the coupling of 3 with dipropargyl ether.

Investigation of a new bis(carboxylate)triazole-based anchoring ligand for dye solar cell chromophore complexes

“…We, and others, have previously reported the preparation and reactivity of the bpy derivative 4-azido-2,2′-bipyridyl. 34,35 This azide precursor was subject to thermally driven cycloaddition with one equivalent of diethyl acetylenedicarboxylate in refluxing toluene to furnish the diester diethyl-1-(2,2′-bipyrid-4-yl)-1,2,3-triazole-4,5-dicarboxy- late. Cycloaddition was confirmed by infrared spectroscopy with the disappearance of the azide stretch corresponding to the starting material (2115 cm −1 ) and the appearance of new CO stretching bands for the carboxylate substituents on the triazole ring (1735 cm −1 ).…”

“…The resonances for the triazoleappended pyridine ring appear at δ 8.85, 8.67 and 7.61 and are shifted as a result of the cycloaddition relative to those of the azide starting material (δ 8.69, 8.15 and 7.34). 35 Routes to ruthenium, iridium and rhenium dctzbpy complexes [Ru(bpy) 2 The final dyes AS16 to AS18 can be readily accessed by hydrolysis with KOH in acetone and subsequent neutralisation. Due to solubility issues, however, and the fact that key properties are expected to differ little after hydrolysis electrochemical characterisation is reported for the more soluble esters AS16-Et 2 to AS18-Et 2 .…”

Upconverting Nanoparticles Prompt Remote Near‐Infrared Photoactivation of Ru(II)–Arene Complexes

“…Click chemistry is ac onvenient strategy for ligand design in inorganic chemistry and has attracted significanta ttention in recenty ears. [43] Such an approacha ffords (bio)orthogonal reactions that are high yielding, selective, and robustunder mild conditions. [44] Inspired by the work of Branda and co-workers, [45] we employed diethyl-3-azidopropyl phosphonate and its azido function to incorporate the phosphonate group into 1 and 2 by using click chemistry.…”

Azide Chemistry – An Inorganic Perspective, Part II[‡][3+2]‐Cycloaddition Reactions of Metal Azides and Related Systems

“…of (azidobipyridine)ruthenium complexes or of (azidocyclopentadienyl)Mn(CO) 3 have been carried out. [487,488] Metzler-Nolte and co-workers reported an impressive series of Cu-catalyzed click reactions of ferrocenylazide, azidomethylferrocene and -ruthenocene as well as other complexes containing azide-functionalized ligands with alkynemodified amino acids, peptides and peptide nucleic acids (PNA) for the labeling of biomolecules. [489] Biologically active trifluoromethyl-substituted metallocene triazoles have been obtained from ferrocene and ruthenocene azides by Cucatalyzed cycloaddition with the respective alkynes.…”