Am. Brouwer et Hjc. Jacobs, PHOTOCHEMISTRY OF 2,5-DIMETHYL-1,3,5-HEXATRIENES IN ARGON MATRICES - FORMATION OF ISOMERS AND ROTAMERS, Recueil des travaux chimiques des Pays-Bas, 114(11-12), 1995, pp. 449
Irradiation of argon matrix-isolated E-2,5-dimethyl-1,3,5-hexatriene r
esults in the formation of thermodynamically less stable rotamers. In
contrast, the corresponding Z-triene readily undergoes light-induced d
ouble bond isomerization to produce the E isomer. The cZc rotamer of Z
-2,5-dimethylhexatriene is obtained by irradiation of 1,4-dimethyl-1,3
-cyclohexadiene. Characteristic features in the UV and IR absorption s
pectra of the various rotational and geometric isomers are discussed.
Recent theoretical work has indicated that single and double bond isom
erizations are both possible starting from the A excited state surface
of E and Z-hexatriene. Experimentally, we have found clear preference
s for either of the two, depending on the initial geometry.