Photochemical properties of cis- and trans-1,2-diphenylethenyl-trimethyltin(IV) and cis-1,2-diphenylpropenyltrimethyltin(IV) : organometallic derivatives of stilbene

Abstract

Upon direct u.v. irradiation in cyclohexane, benzene, alcohol, or chloroform solution, [Sn(CPhCHPh)Me₃](1) undergoes cis-trans isomerization about the olefin double bond as the only efficient reaction. No evidence has been found for either homolytic or heterolytic photocleavage of the Sn–C bond as a primary process. Unusually for stilbenes the photostationary state reached on irradiation (313 nm) is rich in the trans isomer (the ratio cis : trans is 27 : 73 in cyclohexane), because of the higher absorption coefficient of the cis isomer at this wavelength. Isomerization may also be induced following energy transfer from organic sensitizers. Similar results have been observed for [Sn(CPhCMePh)Me₃](2).