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Super-Efficient Platinum Catalyst Derived from a Semiconducting, DMF Solvate: Structural, Spectroscopic, Electrochemical, and Catalytic Characterization



The reaction of [(NH3)4Pt](NO3)2 with LiTCNQF4 (TCNQF4=2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane) in dimethylformamide gives the product [(NH3)4Pt](TCNQF4)2⋅(DMF)4 (1). Subtle changes in the solvent conditions, however, result in a different product, [(NH3)4Pt](TCNQF4)2⋅Et2O⋅(CH3OH)4/3 (2). Both 1 and 2 have been characterized by X-ray crystallography, vibrational (FTIR, Raman) and UV/vis spectroscopy, thermogravimetric analysis and electrochemistry. Single crystals of 1 indicate the presence of 3 D networks supported by hydrogen bonding, whereas the structural analysis of 2 indicates a 2 D layered network, which consists of alternating TCNQF4 and [(NH3)4Pt]2+ layers. The conductivity of a single crystal of 1 at room temperature lies in the semiconducting range (≈2.5×10−6 S cm−1). Unexpectedly, 1 was found to exhibit an exceptionally high catalytic activity for the electron transfer reaction between ferricyanide and thiosulfate ions in aqueous media. Our analysis indicates that the DMF solvates were removed prior to the catalytic reaction, but no other changes that occur in the chemical composition were found. Thus, the active catalyst is [(NH3)4Pt](TCNQF4)2 (3) rather than the starting material 1.

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