Selective Isomerization of <i>cis</i>-PtL₂(1-alkenyl)₂ to <i>cis</i>-PtL₂(2-alkenyl)₂ Complexes

Heating the 1-alkenyl complexes cis-[Pt(1-alkenyl)2L2] [alkenyl = 1-pentenyl, 1-hexenyl, 1-heptenyl, and 1-octenyl; L2 = 1,3-bis(diphenylphosphino)propane (dppp) or 1,2-bis(diphenylphosphino)ethane (dppe)] to 100 °C caused a quantitative isomerization to the corresponding 2-alkenyl complexes cis-[Pt(2-alkenyl)2L2]. This novel isomerization is strongly dependent on the length of the alkenyl chains as well as the nature of the ligand, L2. The new 2-alkenyl complexes were fully characterized by analytical and spectroscopic methods. An X-ray crystal structure of cis-[Pt(2-pentenyl)2(dppp)] confirms this isomerization. Possible reaction mechanisms are discussed.