The experimental gas-phase structures of 1,3,5-trisilylbenzene and hexasilylbenzene and the theoretical structures of all benzenes with three or more silyl substituents

Abstract

This version is available at https://strathprints.strath.ac.uk/10627/ Strathprints is designed to allow users to access the research output of the University of Strathclyde. Unless otherwise explicitly stated on the manuscript, Copyright © and Moral Rights for the papers on this site are retained by the individual authors and/or other copyright owners. Please check the manuscript for details of any other licences that may have been applied. You may not engage in further distribution of the material for any profitmaking activities or any commercial gain. You may freely distribute both the url (https://strathprints.strath.ac.uk/) and the content of this paper for research or private study, educational, or not-for-profit purposes without prior permission or charge.Any correspondence concerning this service should be sent to the Strathprints administrator: strathprints@strath.ac.ukThe Strathprints institutional repository (https://strathprints.strath.ac.uk) is a digital archive of University of Strathclyde research outputs. It has been developed to disseminate open access research outputs, expose data about those outputs, and enable the management and persistent access to Strathclyde's intellectual output. The structures of 1,3,5-trisilylbenzene and hexasilylbenzene in the gas phase have been determined by electron diffraction, and that of 1,3,5-trisilylbenzene by X-ray crystallography. The structures of three trisilylbenzene isomers, three tetrasilylbenzenes, pentasilylbenzene and hexasilylbenzene have been computed, ab initio and using Density Functional Theory, at levels up to MP2/6-31G*. The primary effect of silyl substituents is to narrow the ring angle at the substituted carbon atoms. Steric interactions between silyl groups on neighbouring carbon atoms lead first to displacement of these groups away from one another, and then to displacement out of the ring plane, with alternate groups moving to opposite sides of the ring. In the extreme example, hexasilylbenzene, the SiCCSi dihedral angle is 17.8(8)• .

Intermolecular interactions in group 14 hydrides: Beyond CH···HC contacts

“…An interesting example is the crystal structure of hexyl‐heptahydro‐octasilasesquioxane (lijgug), with a practically collinear O 3 SiH···HSiO 3 moiety ( 3 ) showing a H···H distance of 2.34 Å. For silicon, an angular dependence of the R 3 SiH···HSiR 3 contact distances is seen in the CSD (Figure ), whereby the closer the two interacting silyl groups are to being colinear (measured by the average SiH···Si angle), the shorter the H···H distance can be, with several nearly collinear contacts being at distances shorter than 2.8 Å …”

Syntheses and Structures of 10‐Trimethylelement‐Substituted 1,8‐Dichloroanthracenes

“…In general, these C-Si bond elongations in 3 and the other mentioned alkylsilyl-substituted compounds seem to be caused by repulsive interactions of the aryl-bound hydrogen atoms with the silyl substituents. Without sterically demanding groups at the silicon atom, such long C aryl -Si distances are not observed, neither in solid-state structures [e.g., 1.878(2) Å [8] (9,10-disilylanthracene)] nor in gas-phase structures [e.g., 1.863(3) Å [9] in silylbenzene or 1.892(2) Å [10] in hexasilylbenzene]. In the case of Ant-GeMe 3 (4) the C(10)-Ge(1) bond of 1.986(3) Å is also longer than the C aryl -Ge distances found in 1,8-bis(trimethylgermyl)naphthalene (1.973 and 1.975 Å).…”

Molecular Design of Silicon‐Containing Diazenes: Absorbance ofEandZIsomers in the Near‐Infrared Region

“…Note that silyl-substituted benzenes containing up to six SiR 3 groups were prepared long ago (see for example Refs. [34][35]). B) Silatranyl-substituted azobenzenes Sa-AB 2.…”