Journal of the Korean Physical Society

pISSN 0374-4884 eISSN 1976-8524


J. Korean Phy. Soc. 2011; 59(5(1)): 3192-3200

Published online November 15, 2011

Copyright © The Korean Physical Society.

Infrared and Raman Spectroscopic Studies of Tris(trimethylsilyl)silane Derivatives of ((CH3)3Si)3Si-X [X = H, Cl, OH, CH3, OCH3, Si(CH3)3]: Vibrational Assignments by Hartree-Fock and Density-functional Theory Calculations

Bong Hyun Boo


IR and Raman spectra were measured to elucidate vibrational structures of tris(trimethylsilyl)silane derivatives [((CH3)3Si)3Si-X, X = H, Cl, OH, CH3, OCH3, Si(CH3)3] in the fundamental state. Hartree-Fock (HF) and density-functional theory (DFT) calculations were carried out to study the molecular structure and the vibrational spectra.In the IR spectra, two scaling factors 0.978 and 0.917 were applied to the low (below 2300 cm-1) and high (above 2300 cm-1) energy fundamental frequencies giving the rms deviations 44.0 and 20.4 cm-1, respectively. In the Raman spectra, however, a uniform scaling factor 0.900 was applied to the whole spectra yielding a rms deviation 40.0 cm-1. The comparison between the experimental and simulated IR and Raman spectra of the tris(trimethylsilyl)silane derivatives were made. We cleanly observe the Si-H stretching fundamental at 2052 and 2048 cm-1 in the IR and Raman spectra, respectively. The intensities for the vibrations are relatively intense, compared with those of the C-H stretching fundamental. The skeletal vibrations involving the Si-Si are found to have relatively weak intensities in the IR and Raman spectra. Pure Si-O stretching at 611 cm-1 in the IR spectrum is cleanly observed having the intense absorption both in the IR and Raman spectra. The strong IR intensity is reflected from the electronegativity difference between the corresponding two atoms.

Keywords: Tris(trimethylsilyl)silane derivatives, IR, Raman, HF, DFT, Vibrational assignment