Triazolilideni funzionalizzati come versatili carbeni mesoionici in complessi luminescenti

1,2,3-Triazolylidenes belong to the class of abnormal N-heterocyclic carbenes, which are singlet carbenes with the carbonic center directly bound to at least one nitrogen atom of the heterocycle, and no uncharged resonance structure can be drawn. Since their precursors synthesis is quite simple and it allows the variation of the substituents on the triazolic ring, the use of 1,2,3-triazolylidenes as bidentate ligands for appropriate metallic complexes is very interesting. In the present work I report the synthesis of 1,2,3-triazolium salts 1-benzyl-3-methyl-4-(pyridin-2-yl)-1H-1,2,3-triazol-3-ium (L1-X), 3-methyl-1-phenyl-4-(pyridin-2-yl)-1H-1,2,3-triazol-3-ium (L2-X) (X=OTf, I) and 1,1'-dibenzyl-3-methyl-1H,1'H-[4,4'-bi(1,2,3-triazol)]-3-ium iodide (L3-I), that after the formation of the corresponding triazolylidenes have been employed as bidentate ancillary ligands for the synthesis of three cationic Ir(III) complexes (A-BF4, B-BF4 e C-BF4) and a neutral one (D). The synthetized complexes were characterized with NMR spectroscopy, and DFT computational calculations have been performed to compare, once photophysical characterization has been made, the obtained results with experimental measures.