Far-Infrared Spectrum and Ring-Puckering Potential of Silacyclopent-2-ene

The far-infrared spectrum of silacyclopent-2-ene, Chemical Equation has been recorded, and a series of weak absroption peaks was observed between 120 and 200 cm-1. The absorptions arise from the ring-puckering vibration, and the frequencies fit well with the potential V=31.45 (Z4 +2.40Z2) cm-1, where Z is the puckering coordinate in reduced form. In terms of the dimensioned coordinate X, the potential becomes F = 18.51X105 Z4+18.27X103 X2. The coefficients of the terms in the potential function are unexpectedly large and show that silacyclopent-2-ene is planar and unusually rigid in that position. Interaction between the silicon d orbitals and the carbon-carbon ir bond most likely accounts for the observed results.

Far-Infrared Spectrum and Ring-Puckering Potential of Silacyclopent-2-ene Academic Article