1,2,3-Triazolyl bisphosphine with pyridyl functionality: synthesis, copper() chemistry and application in click catalysis

• Published in: New journal of chemistry 2023-07, Vol.47 (28), p.13538-13546
• Main Authors: Sheokand, Sonu, Mohite, Manali A, Mondal, Dipanjan, Rangarajan, Shalini, Balakrishna, Maravanji S
• Format: Article
• Language: English
• Subjects: Absorption spectra; Alkynes; Catalysis; Charge transfer; Chemical synthesis; Copper compounds; Cycloaddition; Ligands; Room temperature; Substrates
• ISSN: 1144-0546; 1369-9261
• DOI: 10.1039/d3nj01445b

This manuscript describes the synthesis and copper( i ) complexes of pyridine functionalized 1,2,3-triazolyl bisphosphine, [2,6-{(PPh 2 )N(Me)(C 5 H 3 N)(C 2 (PPh 2 )N 3 C 6 H 5 )}] ( L ), photo-physical studies and catalytic application. The reaction of L with copper salts afforded mononuclear complexes [(CuX){2,6-(PPh 2 )N(Me)(C 5 H 3 N)(C 2 (PPh 2 )N 3 C 6 H 5 )}-κ 3 - P , N , P ] (X = Cl, 1 ; Br, 2 ; and I, 3 ). The crystal structures showed highly distorted trigonal pyramidal geometries around copper( i ) centers. The UV-visible absorption spectra of complexes 1-3 showed a shoulder band in the range of 255-260 nm along with an intense UV absorption band in the range of 305-315 nm. The shoulder bands are assigned to ligand-based π → π* and n → π* transitions, whereas the intense bands are assigned to metal-to-ligand charge transfer (MLCT) transitions along with halide-to-ligand charge transfer (XLCT) transitions. Copper complexes 1-3 efficiently promoted azide-alkyne cycloaddition under aerobic conditions, with a very low catalyst loading of 0.2 mol% at room temperature to produce regioselective 1,4-triazoles with a large substrate scope. The gram-scale synthesis carried out with various substrates indicated the stability of copper complex 3 during catalytic reactions. This paper describes the synthesis, copper chemistry and catalytic applications of copper( i ) complexes, containing 1,2,3-triazolyl-bisphosphine with a pyridine moiety, in 1,3-dipolar cycloaddition reactions and one-pot triazole synthesis.