Hula-twist photoisomerization of a styrene derivative examined by argon-matrix-infrared-spectroscopic method

Abstract

IR spectra of α-cyano- o -fluorocinnamonitrile, its vinyl deuterated analogue and the corresponding photoproducts were recorded under Ar matrix isolation conditions (13K). An analysis of the IR spectra, assisted by calculations of the expected absorption signals from these structures, showed that the photoproducts were consistent with the previously assigned Hula-twist (HT) product, an unstable high energy conformer of the parent system. The absence of a significant deuterium isotope effect on rates of photochemical reaction appears to rule out the involvement of a hydrogen-tunnelling mechanism for the HT process.