Synthesis and Properties of Medium-Sized <i>cis,trans</i> -Cycloocta-1,3-diene–Pt(II) Complexes

<i>cis,trans</i>-Cycloocta-1,3-dienes (TCODs) are highly strained and elusive due to rapid 4π-electrocyclization. Here, we report the first stable isolation of <i>cis,trans-</i>cycloocta-1,3-dienes as Pt(II) complexes. X-ray crystallography revealed marked elongation of the trans C═C bond and dihedral distortion relative to <i>trans</i>-cyclooctenes (TCOs). The Pt-TCOD complexes underwent ligand exchange, desilylation to π-allyl species, and enantioselective decomplexation. These findings establish TCOD-metal complexes as isolable surrogates for elusive strained alkenes, providing a foundation for new developments in organometallic and strained-ring chemistry.