A combined DFT and SCRF study of solvent effects on 4-methyl-3-penten-2-one

The IR spectrum of 4-methyl-3-penten-2-one is interpreted with the aid of n ormal coordinate calculations within the Onsager self-consistent reaction f ield (SCRF) model, using a density functional theory (DFT) method at the Be cke3LYP/6-31G* level. The solvent effects on the geometry, energy, dipole m oment, and vibrational frequencies of 4-methyl-3-penten-2-one in the soluti on and in the liquid phase are calculated using the Onsager SCRF model. The calculated vibrational frequencies in the liquid-phase are in good agreeme nt with the experimental values. The solvent reaction field has generally w eak influence. For the two main bands of C=C and C=O mixed vibrational mode s, small frequency shifts (5-6 cm(-1)), but relatively large changes in IR intensities (up to 101 km mol(-1) in the liquid phase) are found. (C) 1999 Elsevier Science BV. All rights reserved.