Determination of vibrational potential energy surfaces from Raman and infrared spectra

Abstract

Raman spectra, far-infrared spectra, and mid-infrared combination band data can be used to determine one-, two-, or three-dimensional potential energy functions which govern conformational changes in small ring molecules. The methods for such analyses are presented along with a brief history of the important contributions to this area. Recent studies on four-, five-, and six-membered rings and on some bicyclic systems are described. Potential difficulties in the calculation of high energy barriers are discussed along with how molecular mechanics calculations can be used to help estimate such barriers. The types of molecules for which the potential energy surfaces have been determined include cyclobutane, cyclopentane, cyclopentene, cyclohexane, cyclohexene, the cyclohexadienes, and the analogous ring systems containing oxygen, sulfur, silicon, nitrogen, phosphorous, or other heteroatoms. A number of bicyclo-hexanes, bicycloheptenes, and other bicyclic molecules have also been investigated. © 1987 IUPAC