Nitrato Complexes of Platinum(IV) with Cesium Cations

Two novel platinum(IV) nitrate complexes, Cs 2 [Pt(NO 3 ) 6 ] ( 1 ) and Cs 2 [Pt 2 (μ-OH) 2 (NO 3 ) 8 ] ( 2 ), are prepared by adding cesium nitrate to a solution of platinum(IV) hydroxide in nitric acid. It is established that the main reaction product is the Cs 2 [Pt(NO 3 ) 6 ] mononuclear complex, while Cs 2 [Pt 2 (μ-OH) 2 (NO 3 ) 8 ] is formed only after the removal of the first portion of the precipitate and subsequent long-term storage of the mother liquor. The structures of the salts are studied by XRD. Crystal data for Cs 2 [Pt(NO 3 ) 6 ] ( 1 ): a = 9.7346(3) Å, b = 11.5072(3) Å, c = 13.6813(2) Å, space group Pbcn , Z = 4. Crystal data for Cs 2 [Pt 2 (μ-OH) 2 (NO 3 ) 8 ] ( 2 ): a = 7.0889(2) Å, b = 14.2216(6) Å, c = 10.7931(4) Å, β = 91.776(1)°, space group P 2 1 / n , Z = 2. It is shown that NO 3 ligands in ( 1 ) occupy atypical positions. The geometry of the complex anion in ( 2 ) is similar to the one described for (Me 4 N) 2 [Pt 2 (μ-OH) 2 (NO 3 ) 8 ]. Powdered samples of ( 1 ) and those of a mixture of ( 1 ) and ( 2 ) are characterized by powder XRD and IR spectroscopy. The obtained compounds are shown to be stable upon long-term storage in air.