New Hydrogen Peroxide Adducts of Alkali Metal Tetracyanoplatinates A(2)[Pt(CN)(4)] center dot H2O2 (A = K, Rb, Cs)

The title compounds have been synthesized by adding hydrogen peroxide to an aqueous solution of A(2)[Pt(CN)(4)] (A = K, Rb, Cs). They grow as yellow needles after concentrating and cooling to 4 degrees C. The Structures were elucidated from single crystal analysis. The isostructural compounds crystallize monoclinically, in space group C2/c with Z = 4, K2Pt(CN)(4) center dot H2O2: a = 13.3751(7), b = 11.2713(6), c = 6.5461(3) angstrom, beta = 105.432(1)degrees, V = 951.3(3) angstrom(3). Rb2Pt(CN)(4) center dot H2O2: a = 13.6103(2), b = 11.6759(1) c = 6.5683(7) angstrom, beta = 106.588(2)degrees, V = 1000.3(2) angstrom(3), Cs2Pt(CN)(4) center dot H2O2: a = 13.9569(2), b = 12.2023(2), c = 6.5957(9) angstrom, beta = 107.590(3)degrees, V = 1069.1(2) angstrom(3). As a remarkable feature, the hydrogen bonds O-H center dot center dot center dot N vary significantly with the cation size: in the Cs compound the O-H bonds are weakest, and the N center dot center dot center dot H interactions are strongest. All three compounds were characterized by differential thermal analysis, thermogravimetry and infrared spectroscopy.