Resonance Raman and ab initio investigation of I2-olefin complexes

We report resonance Raman spectra of selected I2:olefin complexes obtained with excitation within the ∼270 nm absorption band of the complex. Most of the Raman intensity appears in the overtones and combination bands of the nominal I–I stretch and CC stretch modes. Ab initio calculations were done to examine the structure of the ground state of the complex. The Raman vibrational frequencies and the ab initio optimized geometry indicate both the I–I and CC bond order decrease moderately in the ground state complex.