Nature of nonbonded Se•••O interactions characterized by 17O NMR spectroscopy and NBO and AIM analyses
Nature of nonbonded Se•••O interactions characterized by 17O NMR spectroscopy and NBO and AIM analyses
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DOI：
10.1021/ja049690n
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发表时间：
2004-04-28
影响因子：
15
通讯作者：
Tomoda, S
中科院分区：
文献类型：
--
作者：
Iwaoka, M;Komatsu, H;Tomoda, S
为了研究非键合(SEO)-O-的性质...通过相互作用，合成了三个系列的2-取代苯并烯基衍生物[2-(CHO)C6H4SeX(1)，2-(CH2OH)C6H4SeX，(2)，2-(CH(2)OIPR)C6H4SeX(3)；X=Cl，Br，CN，sph，sear，Me]。相对于苯甲醛(PhCHO)，富含O-17的醛1的O-17核磁共振吸收峰相对于苯甲醛(PhCHO)出现前场位移，而富含O-17的醇2和醚3的O-17核磁共振吸收峰相对于苯甲醇(PhCH2OH)出现相反的下场位移。在B3LYP水平上的量子化学计算表明，对于所有的模型化合物，最稳定的构象是分子内非键(SEO)-O-.互动。因此，1-3的相对O-17核磁共振化学位移(Deltadelta(O))将反映(SEO)-O-的强度.互动。自然键轨道(NBO)分析表明，NO-->；sigma(Se-X)(*)轨道相互作用的稳定能((ESEO)-O-…)与(SEO)-O-...单条曲线上的原子距离与O原子的类型无关。另一方面，分子中原子(AIM)分析表明，非键(SEO)-O-...相互作用可以用键临界点的存在、总能量密度((HSeO)-O-…)来表征。它随着相互作用的加强而减小。结果表明，(SEO)-O-...相互作用具有主导的共价特征，而不是静电特征。
To investigate the nature of nonbonded (SeO)-O-... interactions, three series of 2-substituted benzeneselenenyl derivatives [2-(CHO)C6H4SeX (1), 2-(CH2OH)C6H4SeX, (2), 2-(CH(2)OiPr)C6H4SeX (3); X = Cl, Br, CN, SPh, SeAr, Me] were synthesized. The O-17 NMR absorption observed for O-17-enriched aldehydes 1 appeared upfield relative to benzaldehyde (PhCHO), while the opposite downfield shifts relative to benzyl alcohol (PhCH2OH) were observed for O-17-enriched alcohols 2 and ethers 3. The magnitude of both the upfield and the downfield shifts became larger as the electron-withdrawing ability of a substituent X increased. Quantum chemical calculations at the B3LYP level revealed that for all model compounds the most stable conformer has an intramolecular nonbonded (SeO)-O-... interaction. Thus, the relative O-17 NMR chemical shifts (Deltadelta(o)) for 1-3 would reflect the strengths of the (SeO)-O-... interactions. The natural bond orbital (NBO) analysis demonstrated that the stabilization energy due to an no --> sigma(Se-X)(*) orbital interaction ((ESeO)-O-...) correlates with the (SeO)-O-... atomic distance on a single curve irrespective of the type of the O atom. On the other hand, the atoms in molecules (AIM) analysis showed that the nonbonded (SeO)-O-... interactions can be characterized by the presence of a bond critical point, the total energy density ((HSeO)-O-...) of which decreases with strengthening of the interaction. The results suggested that (SeO)-O-... interactions have a dominant covalent character rather than an electrostatic one.