Department of Chemistry, Center of Excellence for Innovation in Chemistry, and Center for Inorganic and Materials Chemistry, Faculty of Science , Mahidol University , Rama VI Road , Ratchathewi, Bangkok 10400 , Thailand.
Center for Organic Electronic and Alternative Energy, Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science , Ubon Ratchathani University , Ubon Ratchathani 34190 , Thailand.
Inorg Chem. 2019 Nov 18;58(22):15110-15117. doi: 10.1021/acs.inorgchem.9b01836. Epub 2019 Oct 30.
A coordination complex, lithium hepta(-butyl)silsesquioxane trisilanolate (; Li-T), a stable intermediate in silsesquioxane (SQ) syntheses, was successfully isolated in 65% yield and found to be highly soluble in nonpolar solvents such as hexane. The structure of Li-T was confirmed by NMR, IR spectroscopy, matrix-assisted laser desorption ionization time-of-flight mass spectrometry, electrospray ionization mass spectrometry, and computational simulation, providing detailed elucidation of the intermolecular self-association of the SQ cage with a box-shaped LiO polyhedron through strong coordination bonds. After acid treatment, Li-T undergoes lithium-proton cationic exchange, yielding hepta(-butyl)silsesquioxane trisilanol (; H-T) quantitatively. The high yield of H-T seems to be influenced by Li-O bonding in the Li-T complex that affects the selective formation of hepta(-butyl)silsesquioxane trisilanolate and the bulky -butyl groups which may prevent decomposition or SQ cage-rearrangement even at reflux under alkaline conditions. Single-crystal X-ray crystallography confirms the presence of the dumbbell-shaped SQ partial cages through strong intermolecular hydrogen bonds. Interestingly, lowering the polarity of the reaction solution by adding dichloromethane results in formation of the cubic octa(-butyl)silsesquioxane (; T) cage in a good yield (47%), which is isolated by crystallization from the reaction solution.
一种配位化合物，即锂七（正-丁基）硅倍半氧烷三硅醇盐（Li-T），是硅倍半氧烷（SQ）合成中的一种稳定中间体，以 65%的产率成功分离，并发现其在非极性溶剂如己烷中具有很高的溶解度。Li-T 的结构通过 NMR、IR 光谱、基质辅助激光解吸电离飞行时间质谱、电喷雾电离质谱和计算模拟得到确认，详细阐明了 SQ 笼通过强配位键与具有盒状 LiO 多面体的分子内自组装。酸处理后，Li-T 经历锂-质子阳离子交换，定量生成七（正-丁基）硅倍半氧烷三硅醇盐（H-T）。高产率的 H-T 似乎受到 Li-T 配合物中 Li-O 键的影响，这种影响影响了 hepta(-butyl)silsesquioxane trisilanolate 的选择性形成和大体积的 -butyl 基团的选择性形成，即使在碱性条件下回流，也可能阻止分解或 SQ 笼重排。单晶 X 射线晶体学证实了通过强分子间氢键存在哑铃状 SQ 部分笼。有趣的是，通过添加二氯甲烷降低反应溶液的极性，导致立方八（正-丁基）硅倍半氧烷（T）笼以良好的产率（47%）形成，通过从反应溶液中结晶分离得到。
