Discrete Platinum(II/IV)-Arsenito Clusters with Pt-As and Pt-O Bonding: [Pt IV (As 3 O 6 ) 2 ] 2- , [Pt 4 II (H 2 AsO 3 ) 6 (HAsO 3 ) 2 ] 2- , and [Pt 2 II As 6 W 4 O 28 ] 10 .

The first two discrete, fully inorganic platinum(II/IV)-arsenito clusters, [ fac -Pt IV (As 3 O 6 ) 2 ] 2- ( PtAs 6 ) and [Pt 4 II (H 2 AsO 3 ) 6 (HAsO 3 ) 2 ] 2- ( Pt 4 As 8 ), as well as the platinum(II)-arsenito heteropolytungstate [Pt 2 II As 6 W 4 O 28 ] 10- ( Pt 2 As 6 W 4 ), have been synthesized in aqueous media using simple one-pot reaction conditions. In PtAs 6 , a Pt IV ion is coordinated to two cyclic, tridentate As 3 O 6 units via oxo-donation (Pt IV -O ∼ 2.02 Å). In Pt 4 As 8 , each Pt II ion is coordinated to four AsO 3 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 Pt 2 As 6 W 4 , each Pt II ion is coordinated by the As atoms of three AsO 3 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 195 Pt NMR.