Unprecedented pentanuclear mixed-valence Pt(II)-Pt(IV) complex anion in Q2[Pt5Cl20] salts (Q = TBA, PPN)

Red crystals of [TBA]2[Pt5Cl20] were obtained by reacting [TBA]2[PtCl6] with an excess of AlCl3 at room temperature in CH2Cl2. The salt [PPN]2[Pt5Cl20] containing the same anion was prepared by reaction of platinum tetrachloride with a small excess of [PPN]Cl in 1,2-dichloroethane at room temperature. Single crystal X-Ray diffraction studies confirmed that both species contained the mixed-valence [Pt5Cl20]2− anion with two dinuclear platinum(IV) Pt2Cl10 fragments organized around a central square planar platinum(II) in a chair arrangement.