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

• Published in: The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment, & general theory Molecules, spectroscopy, kinetics, environment, & general theory, 2015-01, Vol.119 (4), p.786-795
• Main Authors: Wann, Derek A, Robinson, Matthew S, Bätz, Karin, Masters, Sarah L, Avent, Anthony G, Lickiss, Paul D
• Format: Article
• Language: English
• ISSN: 1089-5639; 1520-5215
• DOI: 10.1021/jp511301s

The structures of the molecules (XMe2Si)2C(SiMe3)2, where X = H, Cl, Br, have been determined by gas electron diffraction (GED) using the SARACEN method of restraints, with all analogues existing in the gas phase as mixtures of C 1 - and C 2-symmetric conformers. Variable temperature 1H and 29Si solution-phase NMR studies, as well as 13C NMR and 1H/29Si NMR shift correlation and 1H NMR saturation transfer experiments for the chlorine and bromine analogues, are reported. At low temperatures in solution there appear to be two C 1 conformers and two C 2 conformers, agreeing with the isolated-molecule calculations used to guide the electron diffraction refinements. For (HMe2Si)2C(SiMe3)2 the calculations indicated six conformers close in energy, and these were modeled in the GED refinement.