Structures of Tetrasilylmethane Derivatives (XMe₂Si)₂C(SiMe₃)₂ (X = H, Cl, Br) in the Gas Phase, and their Dynamic Structures in Solution

Abstract

Article:Wann, Derek A. orcid.org/0000-0002-5495-274X, Robinson, Matthew S., Bätz, Karin et al. eprints@whiterose.ac.uk https://eprints.whiterose.ac.uk/ Reuse Unless indicated otherwise, fulltext items are protected by copyright with all rights reserved. The copyright exception in section 29 of the Copyright, Designs and Patents Act 1988 allows the making of a single copy solely for the purpose of non-commercial research or private study within the limits of fair dealing. The publisher or other rights-holder may allow further reproduction and re-use of this version -refer to the White Rose Research Online record for this item. Where records identify the publisher as the copyright holder, users can verify any specific terms of use on the publisher's website. TakedownIf you consider content in White Rose Research Online to be in breach of UK law, please notify us by emailing eprints@whiterose.ac.uk including the URL of the record and the reason for the withdrawal request. The structures of the molecules C(SiXMe 2 ) 4 (X = H, F, Cl, Br) have been determined by gas electron diffraction (GED). Ab initio calculations revealed nine potential minima for each species, with significant ranges of energies. For the H, F, Cl, and Br derivatives nine, seven, two, and two conformers were modelled, respectively, as they were quantum-chemically predicted to be present in measurable quantities. Variable-temperature 1 H and 29 Si solutionphase NMR studies and, where applicable, 13 C NMR, 1 H/ 29 Si NMR shift-correlation, and 1 H NMR saturation-transfer experiments are reported for C(SiXMe 2 ) 4 (X = H, Cl, Br, and also I).At low temperature in solution two conformers (one C 1 -symmetric and one C 2 -symmetric) are observed for each of C(SiXMe 2 ) 4 (X = Cl, Br, I), in agreement with the isolated molecule ab initio calculations carried out as part of this work for X = Cl, Br. C(SiHMe 2 ) 4 is present as a single C 1 -symmetric conformer in solution at the temperatures at which the NMR experiments were performed.