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首页> 外文期刊>RSC Advances >Exploring the origin of the anomeric relationships in 2-cyanooxane, 2-cyanothiane, 2-cyanoselenane and their corresponding isocyano isomers. Correlations between hyper-conjugative anomeric effect, hardness and electrostatic interactions
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Exploring the origin of the anomeric relationships in 2-cyanooxane, 2-cyanothiane, 2-cyanoselenane and their corresponding isocyano isomers. Correlations between hyper-conjugative anomeric effect, hardness and electrostatic interactions

机译：探索2-氰氧烷，2-氰基噻吩，2-氰基苯胺及其相应的异氰酸异构体中的异端关系的起源。超缀合的异常效应，硬度和静电相互作用之间的相关性

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LC-wPBE, LC-BLYP, B3LYP, M06-2X and MP2 methods with the 6-311+G** basis set and natural bond orbital (NBO) interpretation were performed to explore the origin of the anomeric relationships in 2-cyanooxane ( 1 ), 2-cyanothiane ( 2 ), 2-cyanoselenane ( 3 ) and their isocyano isomers [ i.e. 2-iso-cyanooxane ( 4 ), 2-iso-cyanothiane ( 5 ), 2-isocyanoselenane ( 6 )]. All levels of theory used in this work showed that the axial conformations of compounds 1–6 are more stable than their corresponding equatorial forms. By deletion of the electron delocalization between the non-bonded lone pairs of the six-membered rings and the σ ~(*) _(C–CN) and σ ~(*) _(C–NC) anti-bonding orbitals from the Fock matrixes of the axial and equatorial conformations and with re-diagonalization and comparison of the current Fock matrixes with their original forms, we found that these electron delocalizations are responsible for the axial conformation preferences in compounds 1–3 and 4–6 . Importantly, the approach mentioned above revealed that the through-space electronic interactions between the non-bonded lone pairs of the heteroatoms of the six-membered rings and the π* anti-bonding orbitals of the cyano and isocyano groups (π ~(*) _(CN) and π ~(*) _(NC) ) do not play a significant role here. Also, the variations of the differences in the total energies among the axial and equatorial conformations of compounds 1–3 correlate with the variations of differences in their corresponding dipole moments. Although the hyper-conjugative anomeric effect (HCAE) and Pauli exchange-type repulsions (PETR) are in favor of the axial conformations of compounds 1–3 , seemingly, the electrostatic model associated with the dipole–dipole interactions is a determinant here. Interestingly, the attractive electrostatic interactions between two adjacent atoms (AEI) explain reasonably the variations of the structural parameters of compounds 1–3 and 4–6 which are in line with the resultant justification from the HCAE. The axial conformations of compounds 1–3 and 4–6 are harder than their corresponding equatorial conformations but their conformational behaviors could not be interpreted with the Maximum Hardness Principle.
机译：进行LC-WPBE，LC-BLYP，B3LYP，M06-2X和MP2方法，具有6-311 + G **基础集和天然键（NBO）解释，探讨了2-氰氧烷中的异常关系的起源（ 1），2-氰基（2），2-氰基烯酮（3）及其异氰酸异构体[即2-氰基氧烷（4），2-异氰基噻吩（5），2-异氰酸纤维（6）]。本作作品中使用的所有级别理论表明，化合物1-6的轴向构象比其相应的赤道形式更稳定。通过删除六元环的非粘结孤立对之间的电子临床化和σ〜（*）_（C-C-CN）和σ〜（*）_（C-NC）的抗粘合轨道轴向和赤道构象的套筒矩阵和利用其原始形式的当前套管基质的重新对角化和比较，我们发现这些电子取代化对化合物1-3和4-6中的轴向构象偏好负责。重要的是，上述方法揭示了六元环的杂原子的非粘结孤独对之间的通孔电子相互作用和氰基和异氰酸酰基的πβ抗粘合轨道（π〜（*） _（cn）和π〜（*）_（nc））在此处不发挥重要作用。此外，化合物1-3的轴向和赤道构象的总能量之间的差异的变化与其相应的偶极矩的差异的变化相关。虽然超缀合的异常效果（HCAE）和Pauli交换型排斥（PETR）有利于化合物1-3的轴向构象，但是，与偶极偶极相互作用相关的静电模型是这里的决定因素。有趣的是，两个相邻原子（AEI）之间的有吸引力的静电相互作用可合理地解释了化合物1-3和4-6的结构参数的变化，其符合HCAE的所得的理由。化合物1-3和4-6的轴向构象比其相应的赤道构象更硬，但它们的构象行为不能用最大硬度原理解释。

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