...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Structural Chemistry >An Ab Initio Molecular Orbital Theory and Density Functional Theory (DFT) Study of Conformeers and Rotamers of 4-Substituted (Methyl, Hydroxymethyl, Methanoyl, Ethanoyl, Cyano, Fluoro, Chloro, Bromo, Acetoxy) Tetrahydro-2H-thiopyran-1,1-dioxides
【24h】

An Ab Initio Molecular Orbital Theory and Density Functional Theory (DFT) Study of Conformeers and Rotamers of 4-Substituted (Methyl, Hydroxymethyl, Methanoyl, Ethanoyl, Cyano, Fluoro, Chloro, Bromo, Acetoxy) Tetrahydro-2H-thiopyran-1,1-dioxides

机译：从头算分子轨道理论和密度泛函理论（DFT）研究四氢（甲基，羟甲基，甲酰基，乙酰基，氰基，氟，氯，溴，乙酰氧基）四氢-2H-硫代吡喃-1,1的构象异构体和旋转异构体-二氧化物

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

The structures and energies of axial and equatorial conformers and roamers of 4-substituted tetrahydro-2H-thiopyran-1,1-dioxides (tetrahydrothiopyran-1,1-dioxides, thiacyclohexane-1,1-dioxides, thiane-1,1-dioxides, and 1,1-dioxothianes; CH_3, CH_2OH, CHO, COCH_3, CN, F, Cl, Br, and OCOCH_3) were calculated using the hybrid density functionals B3LYP, B3P86, and B3PW91, as well as MP2 and the 6-31G(d), 6-31G(2d), 6-31G(3d), 6-31G(d,p) and 6-31+G(d) basis sets. MP2/6-31+G(d)//HF/6-31+G(d) [-#DELTA#G deg = 1.73 kcal/mol], B3P86/6-31G(d) [-#DELTA#G deg = 1.75 kcal/mol], and B3PW91/6-31G(d) [-#DELTA#G deg = 1.85 kcal/mol] gave conformational free energy (#DELTA#G deg) values at 180 K for 4-methylcyclohexane (-#DELTA#G deg) values at 180 K for 4-methyltetrahydro-2H-thiopyran-1,1-dioxide which wee similar to the reported experimental values for methylcyclohexane (-#DELTA#G deg = 1.80 kcal/mol), 4-methyltetrahydro-2H-thiopyran (-#DELTA#G deg = 1.80 kcal/mol), and other 4-methyl-substituted heterocycles. All levels of theory showed that the conformational preferences of the 4-methanoyl (4-formyl), 4-ethanoyl (4-acetyl), and 4-cyano substitutents were small. The HF calculations gave conformational free energy (-#DELTA#G deg) values for 4-chlorotetrahydro-2H-thiopyran-1,1dioxide which were closer to the experimental value than the MP2 and density functional methods. The best agreement with available experimental data for 4-bromotetrahydro-2H-thiopyran-1,1-dioxide was obtained from the HF/6-31(2d), HF/6-31(3d), the HF/6-31G(3d) calculations. The conformational free energies (-#DELTA#G deg) and relative energies (#DELTA#E) of the conformers and rotamers have been compared with the correspondingly substituted cyclo-hexanes and tetrahydro-2H-thipyrans and are discussed in terms of dipole-dipole (electrostatic) interactions and repulsive nonbonded interactions (steric) in the most stable axial and equatorial conformers. The axial S=O bond lengths are shorter than the equatorial S=O bond lengths and the C2-C3 bond lengths in the substituents with carbon-bonded to the ring are shorter than the C3-C4 and C4-C-5 bond lengths. In constrat, the C2-C3 bond lengths in the 4-halogen and 4-acetoxy substituents are longer than the C3-C4 and C4-C5 bond lengths.
机译：4-取代的四氢-2H-噻喃-1,1-二氧化物（四氢噻喃-1,1-二氧化物，硫代环己烷-1,1-二氧化物，噻吩-1,1-二氧化物）的轴向和赤道构象异构体和漫游子的结构和能量，和1,1-二氧噻吩; CH_3，CH_2OH，CHO，COCH_3，CN，F，Cl，Br和OCOCH_3）使用杂化密度函数B3LYP，B3P86和B3PW91以及MP2和6-31G计算（d），6-31G（2d），6-31G（3d），6-31G（d，p）和6-31 + G（d）基础集。 MP2 / 6-31 + G（d）// HF / 6-31 + G（d）[-＃DELTA＃G度= 1.73 kcal / mol]，B3P86 / 6-31G（d）[-＃DELTA＃G deg = 1.75 kcal / mol]和B3PW91 / 6-31G（d）[-＃DELTA＃G deg = 1.85 kcal / mol]给出了4-甲基环己烷在180 K时的构象自由能值（＃DELTA＃G deg）。 4-甲基四氢-2H-硫代吡喃-1,1-二氧化物在180 K时的-＃DELTA＃G deg）值与甲基环己烷的报道实验值相似（-＃DELTA＃G deg = 1.80 kcal / mol），4 -甲基四氢-2H-噻喃（-＃DELTA＃G deg = 1.80 kcal / mol）和其他4-甲基取代的杂环。所有的理论水平都表明，4-甲酰基（4-甲酰基），4-乙酰基（4-乙酰基）和4-氰基取代基的构象偏爱很小。 HF计算得出4-氯四氢-2H-硫代吡喃-1,1二氧化物的构象自由能（-＃DELTA＃G deg）值比MP2和密度泛函方法更接近实验值。由HF / 6-31（2d），HF / 6-31（3d），HF / 6-31G（4-溴四氢-2H-噻喃-1,1-二氧化物）与现有实验数据的最佳一致性3d）计算。已将构象异构体和旋转异构体的构象自由能（-＃DELTA＃G deg）和相对能（＃DELTA＃E）与相应取代的环己烷和四氢-2H-噻吩进行了比较，并根据偶极-最稳定的轴向和赤道构象异构体中的偶极（静电）相互作用和斥力非键相互作用（空间）。轴向S ＝ O键的长度短于赤道S ＝ O键的长度，并且与碳键合到环上的取代基中的C2-C3键长短于C3-C4和C4-C-5键长。通常，在4-卤素和4-乙酰氧基取代基中的C2-C3键长比在C3-C4和C4-C5键长。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号