Palladium Chemistry in Anhydrous HF/AsF₅ Superacid Medium

Abstract

Pd metal dissolves in anhydrous HF (aHF) acidified with AsF5 in the presence of F2 at ≈︁298 K to give a blue‐green solution from which green Pd(AsF6)2 can be isolated. The latter was also prepared by the interaction of PdF2 and AsF5 in aHF or by the reaction between PdO and F2 in aHF acidified with AsF5. Powdered Pd(AsF6)2 slowly loses AsF5 in a dynamic vacuum. It can therefore be isolated from solution at T < 253 K. Single‐crystals of Pd(AsF6)2 were prepared by solvothermal synthesis from a Pd/AsF5/F2/aHF mixture at 393 K. Pd(AsF6)2 is triclinic with a = 500.9(5), b = 538.3(5), c = 864.9(9) pm, α = 74.46(3), β = 89.97(4), γ = 62.47(2)°, V = 0.1972(3) nm3, and Z = 1, space group P$\bar 1$ (No. 2). The six‐coordinate Pd atoms (coordinated with fluorine) are well separated by isolated AsF6 units. In the 2−175 K temperature range Pd(AsF6)2 follows the Curie−Weiss law with μeff = 3.53 B.M., Tn = 8 K and θp= −13 K. Because of cation‐anion interactions, the AsF6− anions deviate from ideal Oh symmetry. The reduced symmetry can be seen in vibrational spectra, where splitting of the anion vibrational modes can be observed. The oxidation of Pd metal or PdO with F2 in neutral aHF yielded Pd2F6. No reaction was observed between Pd, PdO or Pd2F6 and AsF5 in aHF. All attempts to prepare PdFAsF6 were unsuccessful. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)

Influence of the Increasing Size of the M2+ Cation on the Crystal Structures of XeF5M(SbF6)3 (M = Ni, Mg, Cu, Zn, Co, Mn, Pd) and (XeF5)3[Hg(HF)]2(SbF6)7

“…Because the fluorine atoms of the two crystallographically independent XeF 5 groups of the room-temperature phase are disordered and show large thermal ellipsoids, the Xe-F bonds are not discussed. The Pd-F bond lengths are comparable to those observed in Pd(AsF 6 ) 2 , [17] in which the Pd II atom is six-fold coordinated to F atoms. The Sb-F bonds are in the same range as those in other XeF 5 M(SbF 6 ) 3 compounds.…”

Recent achievements in the synthesis and characterization of metal hexafluorantimonates and hexafluoroaurates

“…The previously reported X-ray single crystal analyses and the X-ray powder diffraction patterns indicate that three structural types are adopted by most of the known compounds with general formula M II (X V F 6 ) 2 (Table 7) [4,5,9,17,18,[28][29][30][31][32][33][34][35][36].…”

“…2) mixtures by elemental F 2 in aHF at room temperature. Pd(SbF 6 ) 2 was prepared from Pd metal, SbF 5 and F 2 in aHF as previously described for Pd(AsF 6 ) 2 [31].…”

Syntheses and Crystal Structures of [H3O]+/M2+ (M = Fe, Zn, Cu, Hg) Salts with [AsF6]–

“…[3,4] It was reported that PdO does not dissolve in an AsF 5 / aHF superacidic system. [5] In the following study it was investigated what kind of products are obtained after MO (M 2+ = Ti, V, Cu, Zn, Nb, Cd, Sn, Hg Pb) is dissolved in aHF/AsF 5 superacid. In addition, reactions between H 3 OAsF 6 and MF 2 (M = Fe, Cr, Ag) in aHF, which was acidified with a large excess of AsF 5 , were investigated.…”