Theoretical IR, Raman and NMR spectra of 1,2-and 1,3-dimethylenecyclobutane

Equilibrium geometries. rotational constants, harmonic vibrational frequenc ies, infrared intensities, Raman activities, and H-1 and C-13 NMR spectra w ere calculated fur 1,2-dimethylenecyclobutane and its less stable isomer 1, 3-dimethylenecyclobutane by using MP2, DFT (B3PW91), and RHF theoretical me thods involving the 6-311++G** basis set. The properties calculated theoret ically have been compared with the experimental values. The internal coordi nates defined fur both isomers were used in the potential energy distributi on (PED) analysis. The theoretical vibrational and NMR spectra form the bas is to differentiate particular compounds in reaction mixture. (C) 2001 Else vier Science B.V. All rights reserved.