Preparation and NMR Spectra of the (Trifluoromethyl)argentates(III) [Ag(CF3) n X4-n ]-, with X = CN (n = 1−3), CH3, C⋮CC6H11, Cl, Br (n = 2, 3), and I (n = 3), and of Related Silver(III) Compounds. Structures of [PPh4][trans-Ag(CF3)2(CN)2] and [PPh4][Ag(CF3)3(CH3)]

Trifluoromethylation of [Ag(CN)2]- with (CF3)2Cd·diglyme yields [Ag(CF3)(CN)]-. The anion is readily oxidized by bromine to the argentates(III), [Ag(CF3)n(CN)4-n ]-, n = 1−4. The stability of these species decreases with an increasing number of CN groups. Halogenation of these complexes with acetyl chloride or with bromine affords the moderately stable (n = 3) or unstable (n = 2) haloargentates of the type [Ag(CF3) n X4-n ]-, X = Cl or Br. Their dehalogenation with AgNO3 in a donor solvent D gives the adducts [Ag(CF3)3D] and [Ag(CF3)2D2]+, respectively. Decomposition of most argentates(III) proceeds by reductive elimination of CF3X (X = Cl, Br, or CN), but ligand exchange with participation of the CF3 groups is also observed. The latter is used to prepare Ag(CF3)3 derivatives from the readily accessible [trans-Ag(CF3)2(CN)2]- anion. The syntheses of methyl(trifluoromethyl)argentates(III) and of (cyclohexylethynyl)(trifluoromethyl)argentates(III) are accomplished by reaction of the cyanoargentates (n = 2, 3) with CH3MgCl or LiC⋮CC6H11, respectively. Often multinuclear (109Ag, 19F, 13C, 1H) NMR data of transient and stable Ag(III) species establish unambiguously not only their constitution but also the square-planar coordination of the metal. Couplings to the spin-1/2 silver nuclei are interpreted on the basis of 5s(Ag) orbital participation in competition with 4d orbital contributions to Ag−CF3 bonding. Crystals of [PPh4][Ag(CF3)2(CN)2] belong to the monoclinic space group C2/c, with a = 18.174(2) Å, b = 7.8881(8) Å, c = 18.881(2) Å, β = 93.036(8)°, and Z = 4, whereas [PPh4][Ag(CF3)3(CH3)] crystallizes in the orthorhombic space group Pca21, with a = 24.941(3) Å, b = 7.2629(6) Å, c = 14.9985(14) Å, and Z = 4. The coordination environments of these two argentates are approximately square planar. The Ag-CF3 bonds in the dicyano complex (2.105(4) Å) are distinctly longer than the Ag−CN linkages (2.013(3) Å). In the [Ag(CF3)3(CH3)]- anion, the Ag−CH3 distance (2.097(5) Å) is slightly shorter than the average Ag−CF3 bond lengths (2.119(10) Å).