Effect of Sulfur Oxidation on the Transmission Mechanism of 4JHH NMR Coupling Constants in 1,3-Dithiane
Effect of Sulfur Oxidation on the Transmission Mechanism of 4JHH NMR Coupling Constants in 1,3-Dithiane
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DOI：
10.1021/jp810981z
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发表时间：
2009-03-19
影响因子：
2.9
通讯作者：
Tormena, Claudio F.
中科院分区：
文献类型：
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作者：
Gauze, Gisele F.;Basso, Ernani A.;Tormena, Claudio F.
根据涉及S=O基团的超共轭相互作用的影响，对1，3-二硫杂环戊烷衍生物的长程(4)J(HH)偶联反应进行了合理化。对1，3-二硫-1-氧化物(2)、顺-1，3-二硫-1，3-二氧化物(3)、1，3-二硫-1，1，3-三氧化物(4)和1，3-二硫-1，1，3，3-四氧化物(5)进行了(4)J(HH)偶联反应的理论和实验研究。用自然键轨道NBO方法研究了超共轭相互作用。涉及LPO、氧孤子对和西格玛*(C2-S1)和西格玛*(S1-C6)反键轨道的超共轭相互作用产生了(4)J(HCQ-HCQ)耦合。长程(4)J(Ha-HAx)，轴向氢原子之间也观察到了耦合，合理地认为这种耦合起源于涉及成键σ(C6-HAx)和反键sigma*(S=O)轨道的超共轭相互作用。只有当S=O群在轴向时，轨道相互作用的对称性才是可能的。
Long-range (4)J(HH) couplings in 1,3-dithiane derivatives are rationalized in terms of the effects of hyperconjugative interactions involving the S=O group. Theoretical and experimental studies of (4)J(HH), couplings were carried out in 1,3-dithiane-1-oxide (2), cis-1,3-dithiane-1,3-dioxide (3), 1,3-dithiane-1,1,3-trioxide (4), and 1,3-dithiane-1,1,3,3-tetraoxide (5) compounds. Hyperconjugative interactions were studied with the natural bond orbital, NBO, method. Hyperconjugative interactions involving the LPO, oxygen lone pair and sigma*(C2-S1) and sigma*(S1-C6) antibonding orbitals yield an increase of (4)J(Hcq - Hcq) couplings. Long-range (4)J(Ha-Hax), couplings were also observed between hydrogen atoms in axial orientation, which are rationalized as originating in hyperconjugative interactions involving the bonding sigma(C6-Hax) and antibonding sigma*(S=O) orbitals. The symmetry for orbital interactions is possible only when the S=O group is in the axial orientation.