AbstractWe report the structure and characterization of 3,4,5-triiodo-2-methylthiophene, obtained as an unexpected, unreported, and significant side product from the iodination of 2-methylthiophene using iodine and iodic acid. Identity of this unexpected product was confirmed by X-ray crystallography and 1H and 13C NMR. The compound crystallizes in the P21/c space group with unit cell parameters a = 16.4183(10) Å, b = 4.1971(3) Å, c = 14.3888(9) Å, β = 111.4442(14), Z = 4, and Dcalc = 3.425 g cm−3. Analysis of residual electron density maps indicated the presence of crystallographic disorder between the 2-methyl and 5-iodo positions leading to a model of two distinct molecules of 3,4,5-triiodo-2-methylthiophene where the atoms of these two groups were exchanged. Non-covalent iodine–iodine and sulfur–iodine interactions are observed.Graphical Abstract Three products, two of which are constitutional isomers, are possible when installing multiple iodine atoms on 2-methylthiophene; X-ray structural analysis and spectral characterization show that the 4,5-diiodo isomer is not formed and that the 3,4,5-triiodo isomer is unexpectedly obtained. Halogen and chalcogen bonding are clearly observed.

中文翻译：

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3,4,5-Triiodo-2-Methylthiophene 的结构和表征：一种意想不到的 2-Methylthiophene 碘化产物

摘要我们报告了 3,4,5-triiodo-2-methylthiophene 的结构和表征，它是通过使用碘和碘酸对 2-methylthiophene 进行碘化而获得的一种意想不到的、未报告的和重要的副产物。通过X-射线晶体学和1H和13C NMR证实了这种意外产物的身份。该化合物在 P21/c 空间群中结晶，晶胞参数 a = 16.4183(10) Å，b = 4.1971(3) Å，c = 14.3888(9) Å，β = 111.4442(14)，Z = 4，和Dcalc = 3.425 g cm−3。残余电子密度图的分析表明 2-甲基和 5-碘位置之间存在晶体学无序，导致了 3,4,5-三碘-2-甲基噻吩的两个不同分子的模型，其中这两组的原子是交换。观察到非共价碘-碘和硫-碘相互作用。图形摘要 当在 2-甲基噻吩上安装多个碘原子时，可能产生三种产物，其中两种是结构异构体；X-射线结构分析和光谱表征表明没有形成4,5-二碘异构体并且意外地获得了3,4,5-三碘异构体。清楚地观察到卤素和硫族键合。