Preparation and NMR spectra of the (trifluoromethyl)argentates(III) [Ag(CF3)(n)X(4-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 [PPh(4)][trans-Ag(CF3)(2)(CN)(2)] and [PPh(4)][Ag(CF3)(3)(CH3)]

Trifluoromethylation of [Ag(CN)(2)](-) with (CF3)(2)Cd . 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)X(4-n)](-), X = Cl or Br. Their dehalogenation with AgNO3 in a donor solvent D gives the adducts [Ag(CF3)(3)D] and [Ag(CF3)(2)D-2](+), respectively. Decomposition of most argentates(III) proceeds by reductive elimination of CF(3)X (X = Cl, Br, or CN), but ligand exchange with participation of the CS 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 equivalent to CC6H11, respectively. Often multinuclear (Ag-109, F-19, C-13, H-1) 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 [PPh(4)][Ag(CF3)(2)(CN)(2)] belong to the monoclinic space group C2/c, with a 18.174(2) A, b = 7.8881(8) Angstrom, c = 18.881(2) Angstrom, beta = 93.036(8)degrees, and Z = 4, whereas [PPh(4)] [Ag(CF3)(3)(CH3)] crystallizes in the orthorhombic space group Pca2(1), with a = 24.941(3) Angstrom, b = 7.2629(6) Angstrom, c = 14.9985(14) Angstrom, 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) Angstrom) are distinctly longer than the Ag-CN linkages (2.013(3) Angstrom). In the [Ag(CF3)(3)(CH3)](-) anion, the Ag-CH3 distance (2.097(5) Angstrom) is slightly shorter than the average Ag-CF3 bond lengths (2.119(10) Angstrom).