Publication: Lithium-Templated Formation of Polyhedral Oligomeric Silsesquioxanes (POSS)
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Issued Date
2019-01-01
Resource Type
ISSN
1520510X
00201669
00201669
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2-s2.0-85074885505
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Mahidol University
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SCOPUS
Bibliographic Citation
Inorganic Chemistry. (2019)
Suggested Citation
Nicha Prigyai, Supphachok Chanmungkalakul, Vuthichai Ervithayasuporn, Nuttapon Yodsin, Siriporn Jungsuttiwong, Nobuhiro Takeda, Masafumi Unno, Jaursup Boonmak, Suda Kiatkamjornwong Lithium-Templated Formation of Polyhedral Oligomeric Silsesquioxanes (POSS). Inorganic Chemistry. (2019). doi:10.1021/acs.inorgchem.9b01836 Retrieved from: https://repository.li.mahidol.ac.th/handle/123456789/50598
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Title
Lithium-Templated Formation of Polyhedral Oligomeric Silsesquioxanes (POSS)
Abstract
© 2019 American Chemical Society. A coordination complex, lithium hepta(i-butyl)silsesquioxane trisilanolate (1; Li-T7), 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-T7 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 Li6O6 polyhedron through strong coordination bonds. After acid treatment, Li-T7 undergoes lithium-proton cationic exchange, yielding hepta(i-butyl)silsesquioxane trisilanol (2; H-T7) quantitatively. The high yield of H-T7 seems to be influenced by Li-O bonding in the Li-T7 complex that affects the selective formation of hepta(i-butyl)silsesquioxane trisilanolate and the bulky i-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(i-butyl)silsesquioxane (3; T8) cage in a good yield (47%), which is isolated by crystallization from the reaction solution.