Theoretical Studies of Monosubstituted and Higher Phenyl-Substituted Octahydrosilsesquioxanes

Abstract

The electronic and structural properties of molecules (octahydrosilsesquioxane, H8Si8O12), the monosubstituted and higher phenyl-substituted octahydrosilsesquioxanes (PhH7Si8O12, Ph2H6Si8O12, (Ph-Ph)H7Si8O12, and Ph8Si8O12), and crystals (H8Si8O12 and octa(phenylsilsesquioxane) acetone solvate (C48H40O12Si8·C3H6O)) have been studied using plane-wave (PW), pseudo-potential (PP), and density functional theory and the generalized gradient approximation (DFT-GGA) methods. The results show that the orbitals near the highest occupied molecular orbitals (HOMOs) and lowest unoccupied molecular orbitals (LUMOs) (inclusive) for the phenyl-substituted polyhedral oligomeric silsesquioxane clusters and crystal are localized on the phenyl functional groups, whereas for both isolated molecular and crystalline H8Si8O12, the HOMO is that with the lone pair on the O atoms.

Azobenzene‐Functionalized Cage Silsesquioxanes as Inorganic–Organic Hybrid, Photoresponsive, Nanoscale, Building Blocks

“…Due to the various possible orientations of the eight peripheral azobenzene arms attached the [SiO 1.5 ] 8 cage, no symmetry restrictions were imposed on OazoSQ structures 31. The reported values for OazoSQ in Figure 9 and Table 2 are the average of eight closely spaced energies, each corresponding to an azobenzene arm (Figure S12 in the Supporting Information).…”

Incompletely Condensed Silsesquioxanes: Formation and Reactivity

“…18 Silicon-oxygen bond distances [1.61-1.62 Å except for Si(6)-O(5)] and silicon-oxygen-silicon bond angles ($150 ) for the cyclic tetrasiloxane structure in upper and lower decks of DDT8OTMS are quite similar with those in cubic Ph 8 Si 8 O 8 (1.61 Å , 149 ). The distances of outer Si-O bond were a little shorter ($1:60 Å ).…”

The gas-phase structure of octaphenyloctasilsesquioxane Si8O12Ph8 and the crystal structures of Si8O12(p-tolyl)8 and Si8O12(p-ClCH2C6H4)8

“…Several structural studies of Si 8 O 12 Ph 8 and related species are detailed in the literature. Although no solvent-free X-ray crystal structure for Si 8 O 12 Ph 8 has previously been reported, there are X-ray studies of this molecule in solvates with C 5 H 5 N/C 6 H 4 Cl 2 12 and Me 2 C=O, 13 and for [Si 8 14 To the best of our knowledge, no previous isolated-molecule studies have been performed, but calculations have been done on the solid-state structure using plane-wave DFT by Lin et al 15 They carried out a computational study of the unsubstituted octahydridosilsesquioxane, Si 8 O 12 H 8 , several phenyl-substituted silsesquioxanes Si 8 O 12 H 8-n Ph n (n = 1 or 2), and the octaphenyl derivative, Si 8 O 12 Ph 8 (1). The authors report that the optimised structure of 1 has low symmetry because of the various orientations of the eight phenyl rings.…”