Structural and computational studies of geometric isomers of 2-(4-methoxystyryl)-1,3-benzothiazole and preparation of their complexes with zinc halides

The 2-(4-methoxystyryl)-1,3-benzothiazole (MeO-sbt) and its complexes with zinc halides of general formula [ZnX2(MeO-sbt)2], X = Cl, Br, I, are prepared. Crystal structure of both geometric isomers cis-2-(4-methoxystyryl)-1,3-benzothiazole 1a and trans-2-(4-methoxystyryl)-1,3-benzothiazole 1b are reported. Optimized structures of isomers 1a and 1b are consistent with X-ray structures. By comparison of calculated and experimental IR spectra as well as experimental NMR data it has been concluded that trans-isomer 1b was initial product. Quantum–mechanical calculations have shown that thermal isomerization in the singlet ground state is not possible at room temperature, but isomerization could be initiated by high temperature or photochemically which had not been studied in this work.