The Raman, Ultraviolet, and Infrared Spectra and the J_SiC NMR Coupling Constant of the Stable Silene (t-BuMe₂Si)(Me₃Si)Si2-Ad. Manifestations of the SiC Double Bond

Abstract

The UV, preresonance Raman, and IR spectra of the stable silene t-BuMe 2 Si(Me 3 Si)Sid2-Ad (1) have been measured as well as its J SidC NMR coupling constant. The normal modes involving the ν(SidC) stretching coordinate were identified for the first time for a stable silene. The experimental data and computations of potential energy distribution and mode eigenvectors show that there is no single vibrational normal mode which can be assigned as ν(SidC). Raman intensity enhancement on approaching resonance strongly supports the conclusion that there are five lines in the region 1000-1370 cm -1 which include significant contribution from the ν(SidC) stretching coordinate. Both the SidC force constant and the J SidC NMR coupling constant (as well as the SidC bond length) indicate that the SidC bond order is smaller in 1 than that in simpler silenes of the type R 2 SidCH 2 (R ) H, Me).

The First Electrochemical Study of a Silene. An Unusually Low Oxidation Potential, Comparable to Those of Strong Organic π-Electron Donors

“…The electrochemical measurements are in line with the picture of the electronic structure of silenes, which emerges from physical measurements 2,4 and from quantum-mechanical calculations. , Thus, the low oxidation potential of 1 is in line with its very low first ionization potential of 6.9 eV,4b similar to that of TTF (6.7−6.9 eV) . This low potential is partially due to the unique characteristics of the SiC double bond (the ionization potential of ethylene is 10.51 eV) 24 and partially to the effect of the particular substituents in 1 (compare to 8.9 eV for H 2 SiCH 2 ( 2 )).…”

“…Since the first report of firm evidence for the existence of compounds with a SiC double bond (silenes) in 1967, several physical properties of transient and stable silenes have been determined. − However, one of the most basic physical properties of silenes, their redox potentials, have not been studied yet. Here we report the first cyclic voltammetry (CV) measurements of a stable silene, (t-BuMe 2 Si)(Me 3 Si)Si2-Ad ( 1 ), which provide important insight into the electronic structure of silenes.…”

Thermodynamic and Theoretical solvation parameters for 2-amino-4,5-dimethylthiophene-3-carboxamide(ADTC) in Ethanol and Mixed EtOH-H2O solvents

“…The data were obtained from frequency analysis by the need or partition function. For vibrational motion, choosing the first vibrational energy K, level to be zero level, the corresponding partition function is expressed as [31,32].…”

“…The translational partition function is used to calculate the translational entropy (which donate the factor e which comes from Stirling's approximation [30][31][32][33][34][35][36]:…”

Thermal and Thermodynamic Parameters for Glycine (GL) Solvation in Water Theoretically

“…Equations above mentioned will be used for estimation of the available thermodynamic for inorganic and organic compounds from the given and evaluated partition functions [5][6][7][8][9][10]. The theoretical calculations were done from the contributions for the translation, rotational motion and electronic contributions.…”