Discrete Platinum(II/IV)-Arsenito Clusters with Pt-As and Pt-O Bonding: [PtIV(As3O6)2]2-, [Pt4II(H2AsO3)6(HAsO3)2]2-, and [Pt2IIAs6W4O28]10

Abstract

The first two discrete, fully inorganic platinum(II/IV)-arsenito clusters, [fac-Pt^IV(As₃O₆)₂]^2- (PtAs₆) and [Pt₄^II(H₂AsO₃)₆(HAsO₃)₂]^2- (Pt₄As₈), as well as the platinum(II)-arsenito heteropolytungstate [Pt₂^IIAs₆W₄O₂₈]^10- (Pt₂As₆W₄), have been synthesized in aqueous media using simple one-pot reaction conditions. In PtAs₆, a Pt^IV ion is coordinated to two cyclic, tridentate As₃O₆ units via oxo-donation (Pt^IV-O ∼ 2.02 Å). In Pt₄As₈, each Pt^II ion is coordinated to four AsO₃ ligands via two oxygens and two As^III atoms in a square-planar fashion (Pt^II-As^III 2.31 Å, Pt^II-O 2.07 Å), resulting in an open cage-like structure, which forms a strong tetrameric assembly in the solid state mediated by two K⁺ counterions. In Pt₂As₆W₄, each Pt^II ion is coordinated by the As atoms of three AsO₃ ligands (Pt^II-As^III 2.38 Å) and an oxo group (Pt^II-O 2.07 Å) in addition to bridging two tungsten ions, and this polyanion was characterized in solution by ¹⁹⁵Pt NMR.