Abstract: | The title compound, cis‐dichloridobis(triethylphosphane)platinum(II) chloroform monosolvate, [PtCl2(C6H15P)2]·CHCl3, has been obtained from ligand scrambling in the cis‐[PtCl2(Cyp2PCl)(PEt3)] (Cyp = cyclopentyl) system in CHCl3 solvent. Unlike the two previously reported unsolvated polymorphs, which are both monoclinic, the compound crystallizes in an orthorhombic setting. Furthermore, the system exhibits a reversible temperature‐dependent structural phase transition, coupling a reduction in anisotropic displacement parameters and a reduction in crystallographic symmetry on cooling. The high‐temperature phase adopts space group Pnma with the complex and solvent molecules sitting across a crystallographic mirror plane (Z′ = 0.5). The low‐temperature phase adopts the space group P212121 with Z′ = 1. |