Equilibrium Structure and Vibrational Spectra of Sila-Adamantane
HOWARD UNIV WASHINGTON DC SCHOOL OF ENGINEERING
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The recent synthesis of a four-fold silylated sila-adamantane molecule C24H72Si14, Td, J. Fischer, J. Baumgartner, and C. Marschner, Science 310, 2005 825 is the first attempt of making the silicon analogue of adamantane. It has adamantane-like Si10 core, capped by methyl and silymethyl ligands. We report its electronic structure, vibrational spectrum, and the infra-red and Raman spectra calculated within the density functional formalism using large polarized Gaussian basis sets. The properties of sila-adamantane are compared with exact silicon analogue Si10H14 of adamantane. Results show that replacing hydrogens in Si10H16 by methyl and silymethyl ligands results in expansion of the Si10 core and are responsible for large number of peaks in the Raman spectrum. The Si-C stretch at 664 cm-1 and methyl deformations frequencies compare well with recent measurements of vibrational frequencies of methylated silicon surface.
- Organic Chemistry
- Atomic and Molecular Physics and Spectroscopy