Vibrational spectra, quantum chemical calculations and spectral assignments of 1,1-difluoro-1-silacyclohexane.
Raman spectra of 1,1-difluoro-1-silacyclohexane as a liquid, and as a solid at 78 K were recorded and depolarization data obtained. The infrared spectra of the vapour, liquid and amorphous and crystalline solids have been studied. In the low temperature IR and Raman spectra eight and three bands, respectively, were shifted a few cm(-1) when the sample crystallized. No bands vanished after crystallization in agreement with the assumption that only one conformer (chair) was present in all the states of aggregation. The compound exists in the stable chair conformation, whereas in the parent silacyclohexane a possible twist form should have more than 15 kJ mol(-1) higher energies than the chair, as derived from various calculations. The wavenumbers of the vibrational modes were calculated in the harmonic and anharmonic approximation employing B3LYP/cc-pVTZ calculations. The 27 A' and 21 A″ fundamentals were assigned on the basis of the calculations, infrared vapour contours, Raman depolarization measurements and infrared and Raman band intensities. An average, relative deviation of 1.5% was found between the observed and the anharmonic wavenumbers for the 48 modes.
Department of Chemistry & Biochemistry, College of Charleston, Charleston, SC 29403, USA.
Gamil A
GA
Guirgis
Department of Chemistry & Biochemistry, College of Charleston, Charleston, SC 29403, USA.
Horace W
HW
Dukes
Department of Chemistry & Biochemistry, College of Charleston, Charleston, SC 29403, USA.
Justin K
JK
Wyatt
CTCC, Department of Chemistry, University of Oslo, P.O. Box 1033, NO-0315 Oslo, Norway.
Claus J
CJ
Nielsen
CTCC, Department of Chemistry, University of Oslo, P.O. Box 1033, NO-0315 Oslo, Norway.
Anne
A
Horn
CTCC, Department of Chemistry, University of Oslo, P.O. Box 1033, NO-0315 Oslo, Norway; Department of General Physics and Spectroscopy, Vilnius University, Vilnius 2734, Lithuania.
Valdemaras
V
Aleksa
CTCC, Department of Chemistry, University of Oslo, P.O. Box 1033, NO-0315 Oslo, Norway. Electronic address: peter.klaboe@kjemi.uio.no.
Peter
P
Klaeboe
D003460:Crystallization; D006573:Heterocyclic Compounds, 1-Ring / Q000737:chemistry*; D008956:Models, Chemical; D008968:Molecular Conformation; D017646:Organosilicon Compounds / Q000737:chemistry*; D011789:Quantum Theory; D013055:Spectrophotometry, Infrared; D013059:Spectrum Analysis, Raman / Q000379:methods; D014732:Vibration
D006573:Heterocyclic Compounds, 1-Ring; D017646:Organosilicon Compounds
1,1-Difluoro-1-silacyclohexane; DFT calculations; Infrared and Raman spectra; Vibrational assignments