Conformational analysis and structure elucidation of 2,3-dimethyl- and 2,4-dimethyl-2,4-hexadienes by AM1 and He(I) ultraviolet photoelectron spectroscopy

A study of (E)-2,3-dimethyl-2,4-hexadiene (E-3) and (Z)-2,3-dimethyl-2,4-hexadiene (Z-3) by the semiempirical computational method AM1 and He(I) ultraviolet photoelectron spectroscopy (UPS) has established that this combination of AM1/UPS will be generally useful for detailing conformational and electronic properties of alkyl-substituted 1,3-dienes. This method was used to elucidate the structures of the stereoisomeric 2,4-dimefhyl-2,4-hexadienes obtained from the photolysis of 1,3,3,4-tetramethylcyclobutene (2). Keywords: 2,3- and 2,4-dimethyl-2,4-hexadienes, conformational analysis, AM1, He(I) photoelectron spectroscopy.