Switching by Photochemical trans–cis Isomerization of Azobenzene Substituents in Organoplatinum Complexes

A diimine ligand, LL = 2-C5H4NCHN-4-C6H4NNPh, which carries a trans-azobenzene substituent, forms the dimethylplatinum­(II) complex [PtMe2(LL)], which undergoes trans oxidative addition with MeI, PhCH2Br, Br2, and I2 to give the corresponding organoplatinum­(IV) complexes [PtIMe3(LL)], [PtBrMe2(CH2Ph)­(LL)], [PtBr2Me2(LL)], and [PtI2Me2(LL)], respectively. The ligand and the platinum­(II) and platinum­(IV) complexes are shown to undergo trans–cis isomerization of the azobenzene substituent upon irradiation, and the cis isomers then underwent slow thermal isomerization back to the more stable trans isomers.