The Structure and Characterization of 3,4,5-Triiodo-2-Methylthiophene: An Unexpected Iodination Product of 2-Methylthiophene
The Structure and Characterization of 3,4,5-Triiodo-2-Methylthiophene: An Unexpected Iodination Product of 2-Methylthiophene
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DOI：
10.1007/s10870-019-00770-z
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发表时间：
2019-09
影响因子：
0.8
通讯作者：
Dinesh G. Patel;Eric D. Sylvester;Nicholas R. LeValley;Travis B. Mitchell;J. Benedict
中科院分区：
文献类型：
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作者：
Dinesh G. Patel;Eric D. Sylvester;Nicholas R. LeValley;Travis B. Mitchell;J. Benedict
摘要我们报道了3，4，5-三碘-2-甲基噻吩的结构和表征，它是用碘和碘酸将2-甲基噻吩碘化得到的一种意想不到的、未报道的重要副产物。通过X射线晶体学和1H和13 C NMR证实了该意外产物的身份。该化合物在P21/c空间群中结晶，晶胞参数a = 16.4183（10），B= 4.1971（3），c= 14.3888（9），β = 111.4442（14），Z= 4，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3，4，5-三碘-2-甲基噻吩的两个不同分子的模型，其中这两个基团的原子被交换。在2-甲基噻吩上安装多个碘原子时，可能会产生三种产物，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，而是意外地得到3，4，5-三碘异构体。清楚地观察到卤素和硫族元素键合。
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 and1H and13C NMR. The compound crystallizes in the P21/c space group with unit cell parametersa= 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 AbstractThree 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.