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Has AuF7 Been Made?




Sebastian Riedel, Martin Kaupp, "Has AuF7 Been Made?" Inorg. Chem. 2006, 45, 1228 - 1234.
 
Quantum chemical calculations at DFT (BP86, B3LYP, BHLYP), MP2, CCSD, and CCSD(T) levels have been carried out on various fluoro complexes of gold in oxidation states +V through +VII, to evaluate the previously claimed existence of AuF7. The calculations indicate clearly that elimination of F2 from AuF7 is a strongly exothermic reaction, with a low activation barrier. This is inconsistent with the reported stability of AuF7 up to room temperature. A reported experimental vibrational frequency at 734 cm-1 for AuF7 could not be verified computationally. It is concluded that the reported observation of AuF7 was probably erroneous. As the calculations indicate also an extremely large electron affinity and little stability for AuF6, Au+V remains the highest well-established gold oxidation state.
     
 



After 20 Years, Theoretical Evidence that "AuF7" is Actually AuF5· F2




Daniel Himmel, Sebastian Riedel, "After 20 years, theoretical evidence that "AuF7" is actually AuF5 · F2 " Inorganic Chemistry 2007, 46, 5338 - 5342.
   
   
 
Quantum-chemical calculations at the DFT (BP86, PBE, TPSS, B3LYP, PBE0), MP2, CCSD, and CCSD(T) levels have been carried out to characterize the putative AuF7 reported in 1986 by Timakov et al. Our calculations indicate clearly that the species claimed to be AuF7 had not been synthesized. Instead, a new gold fluoride complex AuF5·F2 was prepared. This complex is 205 kJ mol-1 more stable than the proposed AuF7 species and the elimination of F2 is calculated to be endothermic. This is consistent with the reported stability of the product. A reported experimental vibrational frequency at 734 cm-1 was verified computationally to be the F-F stretching mode of the end-on coordinated F2 molecule. This result is in line with the recently published trends in the highest attainable oxidation states of the 5d transition metals were Au(V) remains the highest oxidation state of gold.