coesite (17)O2Si | 77783-56-3

• 分子结构分类: 有机化合物
• 英文名称: coesite (17)O2Si
• 英文别名: coesite
• CAS: 77783-56-3
• 化学式: O₂Si
• 分子量: 62.0855
• InChiKey: VYPSYNLAJGMNEJ-ZDOIIHCHSA-N

计算性质

• 辛醇/水分配系数(LogP)：
  -0.62
• 重原子数：
  3.0
• 可旋转键数：
  0.0
• 环数：
  0.0
• sp3杂化的碳原子比例：
  0.0
• 拓扑面积：
  34.14
• 氢给体数：
  0.0
• 氢受体数：
  2.0

反应信息

• 作为反应物：
  描述：

  magnesium hydroxide 、 coesite (17)O2Si 以 neat (no solvent) 为溶剂， 生成 magnesium silicate
  参考文献：
  名称：

  ¹⁷O and ²⁹Si NMR Parameters of MgSiO₃ Phases from High-Resolution Solid-State NMR Spectroscopy and First-Principles Calculations

  摘要：

  The Si-29 and O-17 NMR parameters of six polymorphs of MgSiO3 were determined through a combination of high-resolution solid-state NMR and first-principles gauge including projector augmented wave (GIPAW) formalism calculations using periodic boundary conditions. MgSiO3 is an important component of the Earth's mantle that undergoes structural changes as a function of pressure and temperature. For the lower pressure polymorphs (ortho-, clino-, and protoenstatite), all oxygen species in the O-17 high-resolution triple-quantum magic angle spinning (MAS) NMR spectra were resolved and assigned. These assignments differ from those tentatively suggested in previous work on the basis of empirical experimental correlations. The higher pressure polymorphs Of MgSiO3 (majorite, akimotoite, and perovskite) are stabilized at pressures corresponding to the Earth's transition zone and lower mantle, with perovskite being the major constituent at depths >660 km. We present the first O-17 NMR data for these materials and confirm previous 29Si work in the literature. The use of high-resolution multiple-quantum MAS (MQMAS) and satellite-transition MAS (STMAS) experiments allows us to resolve distinct oxygen species, and full assignments are suggested. The six polymorphs exhibit a wide variety of structure types, providing an ideal opportunity to consider the variation of NMR parameters (both shielding and quadrupolar) with local structure, including changes in coordination number, local geometry (bond distances and angles), and bonding. For example, we find that, although there is a general correlation of increasing O-17 chemical shift with increasing Si-O bond length, the shift observed also depends upon the exact coordination environment.

  DOI：

  10.1021/ja074428a
• 作为产物：
  描述：

  四氯化硅 、 氧-17原子 以 水 为溶剂， 生成 coesite (17)O2Si
  参考文献：
  名称：

  二元铝硅酸盐及其他相关玻璃的高分辨率多核核磁共振结构研究

  摘要：

  已经使用高分辨率 27Al、17O 和 29Si NMR 光谱技术研究了具有 0.4 至高达 12.0 wt% Al2O3 的均质二元 SiO2-Al2O3 玻璃的结构。发现所有玻璃都含有 4 倍、5 倍和 6 倍配位的 Al 位点（AlIV、AlV 和 AlVI）的混合物。这些位点的相对比例很大程度上取决于成分，其中 AlIV (AlV) 在具有 <1 wt% (≥7 wt%) Al2O3 的玻璃中占主导地位。另一方面，没有观察到铝形态对假想温度的显着依赖性。发现这些玻璃中大部分 AlVI 位点的配位多面体异常扭曲，类似于结晶 Al2SiO5 多晶型物的情况。17O NMR 光谱显示在这些玻璃中存在三种类型的氧位点，Si-O-AlV、Si-O-AlIV 和 Si-O-Si。29Si MAS NMR 光谱证实了这些结果，并揭示了 Q4 位点的存在，有和没有 Al 次近邻。假设四面体...

  DOI：

  10.1021/jp031348u

文献信息

• ¹⁷O Multiple-Quantum MAS NMR Study of High-Pressure Hydrous Magnesium Silicates
  作者：Sharon E. Ashbrook、Andrew J. Berry、Stephen Wimperis

  DOI：10.1021/ja004290v

  日期：2001.7.1

  Two O-17-enriched hydrous magnesium silicates, the minerals hydroxyl-chondrodite (2Mg(2)SiO(4). Mg(OH)(2)) and hydroxyl-clinohumite (4Mg2SiO(4). Mg(OH)(2)), were synthesized. High-resolution "isotropic" O-17 (I = 5/2) NMR spectra of the powdered solids were obtained using three- and five-quantum MAS NMR at magnetic field strengths of 9.4 and 16.4 T. These multiple-quantum (MQ) MAS spectra were analyzed to yield the O-17 isotropic chemical shifts (delta (CS)) and quadrupolar parameters (C-Q, eta and their "product" P-Q) of the distinct oxygen sites resolved in each sample. The values obtained were compared with those found previously for forsterite (Mg2SiO4). The O-17 resonances of the protonated (hydroxyl) sites were recorded and assigned with the aid of O-17 H-1} cross-polarization and comparison with the spectrum of O-17-enriched brucite (Mg(OH)(2)). Using all of these data, complete assignments of the five crystallographically inequivalent oxygen sites in hydroxylchondrodite and of the nine such sites in hydroxyl-clinohumite are suggested. The validity of these assignments are supported by the observation of a correlation between O-17 isotropic chemical shift and Si-O bond length. The Si-29 MAS NMR spectra of the two minerals were also obtained.