Room temperature syntheses of AuF6- and PtF6- salts, Ag+AuF6-, Ag2+PtF62-,and Ag2+PdF62- and an estimate for E(MF6-) [M = Pt, Pd]

Solutions of AuF4- or PtF62- salts, prepared from the metals at similar to 20 degrees C, in liquid anhydrous hydrogen fluoride (aHF), made basic with alkali fluorides, are further oxidized by photodissociated F-2 (visible or near-UV Light) to give AuF6- or PtF6- salts, including O2+AuF6- (with O-2 i n the F-2). Similar photochemical oxidation of PdF62- salts does not occur. This new synthetic approach has provided LiAuF6 and LiPtF6 for the first t ime, each of which has the LiSbF6 type (<R(3)over bar>) structure with (hex agonal cell): LiAuF6, a = 4.9953(9) Angstrom, c = 13.704(3) Angstrom, V/Z = 98.71(6) Angstrom(3); LiPtF6, a = 5.0236(7) Angstrom, c = 13.623(2) Angstr om, V/Z = 99.25(5) Angstrom(3). Interaction of AuF6- with Ag+ gives Ag+AuF6 - (<R(3)over bar>, a = 5.283(3) Angstrom, c = 15.053 Angstrom, V/Z = 121.3( 2) Angstrom(3)), whereas PtF62- or PdF62- stabilize Ag2+ as Ag2+Pt(Pd)F-6(2 -) (<R(3)over bar>; AgPtF6: a = 5.049(8) Angstrom, c = 14.46(2) Angstrom, V /Z = 106.4(5) Angstrom(3); and AgPdF6, a = 5.00(4) Angstrom, c = 14.6(2) An gstrom, V/Z = 105(3) Angstrom(3)). New cubic modifications (probable space group Ia3) have been found for AgMF6 (M, a value, Angstrom): Ru, 9.653(10); Os, 9.7318(9); Ir, 9.704(2). The preference for Ag2+Pt(Pd)F-6(2-) over AgPt(Pd)F-6(-) is attributed to a second electron affinity of Pt(Pd)F-6, E(Pt (Pd)F-6(-)) > 60 kcal mol(-1).