Eujen Reint, Hoge Berthold, Brauer David J.
Anorganische Chemie, Fachbereich 9, Universität-GH, 42097 Wuppertal, Germany.
Inorg Chem. 1997 Mar 26;36(7):1464-1475. doi: 10.1021/ic9610445.
Trifluoromethylation of Ag(CN)(2) with (CF(3))(2)Cd.diglyme yields Ag(CF(3))(CN). The anion is readily oxidized by bromine to the argentates(III), Ag(CF(3))(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(CF(3))(n)X(4-n), X = Cl or Br. Their dehalogenation with AgNO(3) in a donor solvent D gives the adducts [Ag(CF(3))(3)D] and Ag(CF(3))(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 CF(3) groups is also observed. The latter is used to prepare Ag(CF(3))(3) derivatives from the readily accessible trans-Ag(CF(3))(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 CH(3)MgCl or LiC&tbd1;CC(6)H(11), respectively. Often multinuclear ((109)Ag, (19)F, (13)C, (1)H) 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-CF(3) bonding. Crystals of [PPh(4)][Ag(CF(3))(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, beta = 93.036(8) degrees, and Z = 4, whereas [PPh(4)][Ag(CF(3))(3)(CH(3))] crystallizes in the orthorhombic space group Pca2(1), 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-CF(3) bonds in the dicyano complex (2.105(4) Å) are distinctly longer than the Ag-CN linkages (2.013(3) Å). In the Ag(CF(3))(3)(CH(3)) anion, the Ag-CH(3) distance (2.097(5) Å) is slightly shorter than the average Ag-CF(3) bond lengths (2.119(10) Å).
[Ag(CN)₂]⁻与(CF₃)₂Cd·二甘醇二甲醚发生三氟甲基化反应生成[Ag(CF₃)(CN)]⁻。该阴离子很容易被溴氧化为三价银酸盐[Ag(CF₃)ₙ(CN)₄₋ₙ]⁻，n = 1 - 4。这些物种的稳定性随着氰基数量的增加而降低。用乙酰氯或溴对这些配合物进行卤化反应，可得到中等稳定性（n = 3）或不稳定（n = 2）的卤化银酸盐[Ag(CF₃)ₙX₄₋ₙ]⁻，X = Cl或Br。它们在给体溶剂D中与AgNO₃发生脱卤反应，分别生成加合物[Ag(CF₃)₃D]和[Ag(CF₃)₂D₂]⁺。大多数三价银酸盐的分解是通过CF₃X（X = Cl、Br或CN）的还原消除进行的，但也观察到了CF₃基团参与的配体交换。后者用于从易于获得的[反式-Ag(CF₃)₂(CN)₂]⁻阴离子制备Ag(CF₃)₃衍生物。甲基（三氟甲基）银酸盐（III）和（环己基乙炔基）（三氟甲基）银酸盐（III）的合成分别通过氰基银酸盐（n = 2, 3）与CH₃MgCl或LiC≡CC₆H₁₁反应来完成。通常，瞬态和稳定的Ag(III)物种的多核（¹⁰⁹Ag、¹⁹F、¹³C、¹H）NMR数据不仅明确确定了它们的结构，还确定了金属的平面正方形配位。与自旋-(1)/(2)银核的耦合是基于5s(Ag)轨道参与与4d轨道对Ag - CF₃键合的贡献竞争来解释的。[PPh₄][Ag(CF₃)₂(CN)₂]的晶体属于单斜空间群C2/c，a = 18.174(2) Å，b = 7.8881(8) Å，c = 18.881(2) Å，β = 93.036(8)°，Z = 4，而[PPh₄][Ag(CF₃)₃(CH₃)]结晶于正交空间群Pca2(1)，a = 24.941(3) Å，b = 7.2629(6) Å，c = 14.9985(14) Å，Z = 4。这两种银酸盐的配位环境近似为平面正方形。二氰基配合物中的Ag - CF₃键（2.105(4) Å）明显长于Ag - CN键（2.013(3) Å）。在[Ag(CF₃)₃(CH₃)]⁻阴离子中，Ag - CH₃距离（2.097(5) Å）略短于平均Ag - CF₃键长（2.119(10) Å）。
