Conformational study of molecules with asymmetric isotopic substitution. Ring puckering of 1-silacyclobutane-1-d/sub 1/
1-Silacyclobutane-1-d/sub 1/ has been prepared and its infrared spectra have been analyzed. Several ring-puckering transitions have been observed in the far-infrared region and sum and difference bands have been observed in the Si-H stretching region. A ring-puckering potential function which simultaneously fits the data for the D/sub 0/, d/sub 1/, and d/sub 2/ isotopic forms has been determined. Calculation of the wave functions for the d/sub 1/ molecule shows that each of the lowest two very nearly degenergy states (nu = 0 and nu = 1) corresponds to only one distinct molecular conformation. Similarly, the nearly degenerate nu = 2 and nu = 3 states are primarily restricted to specific conformations. Doublets observed for the Si-H and Si-D stretching bands, corresponding to stretches from equitorial or axial positions, confirm these calculations. Model calculations on related systems demonstrate that both a sufficiently large barrier height and an asymmetry of the kinetic energy expansions are necessary for the conformational separation according to vibrational states. Although the reduced masses of the two conformers of 1-silacyclobutane-1-d/sub 1/ differ by only 0.20%, this is enough to produce the observed conformational discrimination.
- Research Organization:
- Texas A and M Univ., College Station
- OSTI ID:
- 6497631
- Journal Information:
- J. Phys. Chem.; (United States), Journal Name: J. Phys. Chem.; (United States) Vol. 86:22; ISSN JPCHA
- Country of Publication:
- United States
- Language:
- English
Similar Records
Far-infrared and combination-band spectra of the ring-puckering and ring-flapping vibrations of phthalan: A failure of the one-dimensional model
Far-infrared and Raman spectra of the ring-puckering vibration of 2,3-dihydrothiophene. One- and two-dimensional potential energy surfaces and the barrier to planarity
Related Subjects
400301 -- Organic Chemistry-- Chemical & Physicochemical Properties-- (-1987)
400302* -- Organic Chemistry-- Isotope Effects-- (-1987)
ALKANES
CHEMICAL PREPARATION
CYCLOALKANES
DATA
DEUTERIUM
ENERGY LEVELS
EXPERIMENTAL DATA
HYDROCARBONS
HYDROGEN ISOTOPES
INFORMATION
INFRARED SPECTRA
ISOTOPE EFFECTS
ISOTOPES
LIGHT NUCLEI
NUCLEI
NUMERICAL DATA
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
ORGANOMETALLIC COMPOUNDS
SILICON COMPOUNDS
SPECTRA
STABLE ISOTOPES
SYNTHESIS