A New Thiatriazine Isomer: Synthesis, Tautomerism, and Molecular Structure of 3,6-Diphenyl-4<i>H</i>-1,2,4,5-thiatriazine as a Precursor to the 1,2,4,5-Thiatriazinyl Radical
作者:John M. Farrar、Mahesh K. Patel、Piotr Kaszynski、Victor G. Young
DOI:10.1021/jo991126l
日期:2000.2.1
with Ph(3)Sb. The weak ESR quintet (a(N) = 1.03 mT, g = 2.0103) observed in the latter case correlates well with the molecular structure of 4, but the results of DFT calculations are ambiguous. Ab initio calculations show that 4H-1,2, 4,5-thiatriazine (I-4H) is the most stable tautomer and is the second most stable isomer among the six possible thiatriazines. All isomeric thiatriazinyl radicals exhibit
通过对9进行氧化环化反应制得4H-1,2,4,5-噻三嗪(5)的二苯衍生物。通过X射线衍射获得的5的分子结构[斜方体,Pna2(1),a = 9.7746( 13)A,b = 21.692(2)A,c = 5.6580(8)A],与从头算计算得出的结果相比具有优势。噻三嗪5用作3,6-二苯基-1,2,4,5-噻三嗪基(4)的前体,方法是用PbO(2)氧化,或转化为Ph( 3)在后一种情况下观察到的较弱的ESR五重态(a(N)= 1.03 mT,g = 2.0103)与4的分子结构密切相关,但DFT计算的结果却模棱两可。从头算计算表明,4H-1,2,4,5-噻三嗪(I-4H)是最稳定的互变异构体,并且是六种可能的噻三嗪中第二稳定的异构体。所有异构的噻三嗪基自由基均显示出相似的自旋分布模式。计算得出1,2,4,5-噻三嗪基(IR)的稳定性比最稳定的1,2,4,6异构体II-R低1 kcal /