An efficient synthesis of 5‐organotellanyl‐1H‐1,2,3‐triazole compounds was accomplished through [3+2] cycloaddition reaction of organic azides and (organotellanyl)alkynes. Additionally, 5‐organotellanyl‐1H‐1,2,3‐triazoles were readily functionalized at the 5‐position by using a Sonogashira cross‐coupling reaction, leading to highly functionalised triazoles. The regiochemistry of the products was assessed by two‐dimensional NMR spectroscopic experiments and X‐ray crystallography.
Crystal structure analysis of the isomeric N,N′-bis(pyridin-n-ylmethyl)ethanedithioamides, n = 2 (1), 3 (2) and 4 (3), show a planar conformation for 1 and conformations whereby the pyridyl rings lie orthogonal and to either side of the central residue for each of 2 and 3. The universal adoption of the all ZZ conformation about the central C-N bonds, which have double bond character, is ascribed to the presence of intramolecular N-H…S hydrogen bonds that close S(5) rings. The gasphase geometry optimised structure for 1 is the same as the experimental structure which features intramolecular amine-N-H…N(pyridyl) hydrogen bonds. The open structures found for 2 and 3 differ from the somewhat flattened optimised structures. Systematic variations in the geometric parameters characterising the central C 2 N 2 S 2 residue, in particular the double-bond character of the C-N bond and the elongation of the central C-C bond are shown by theory to be due to conjugative n N → π* C=S interactions and n S → σ* C-C hyperconjugation, respectively.
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