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[Au(CF3)(CO)]: A Gold Carbonyl Compound Stabilized by a Trifluoromethyl Group

This work was supported by the Spanish MICINN (DGPTC)/FEDER (Project CTQ2008-06669-C02-01/BQU) and the Gobierno de Aragon (Grupo Consolidado 21: Quimica Inorganica y de los Compuestos Organometalicos).

The first mononuclear PtIII complex. Molecular structures of (NBu4)[PtIII(C6Cl5)4] and of its parent compound {NBu4}2[PtII(C6Cl5)4]·2CH2Cl2

(NBu4)[PtIII(C6Cl5)4], fully characterized by crystallographic, spectral, and magnetic measurements has been isolated by oxidation with halogens or TICl3 of the parent compound (NBu4)2[PtII(C6CL5)4], which has also been analysed by X-ray crystallography.

Preparation of cis-bis-acetylene-bis(pentafluorophenyl)-palladium(II) and -platinum(II) complexes, crystal structure of cis-[Pt(C6F5)2 (PhCCPh)2]

Abstract Treatment of cis-[M(C6F5)2(THF)2] (M = Pd, Pt; THF = tetrahydrofuran) with PhCCPh has given the novel bis-acetylene-palladium(II) and -platinum(II) complexes cis-[M(C6F5)2(PhCCPh)2]; these are stable even though there seems to be no significant π-back bonding according to the X-ray structure of the platinum complex.

Synthesis of neutral and cationic pentafluorophenylpalladium(I) derivatives. Insertion versus coordination of isocyanides in binuclear palladium(I) complexes

Abstract Reaction between PdX(C6F5)(dpm)2 (dpm = bis(diphenylphosphino)methane; X = Cl, Br, I, CNO or C6F5) and Pd2(dba)3CHCl3 (dba = dibenzylideneacetone) gives, the pentafluorophenyl palladium(I) derivatives [XPd(μ-dpm)2Pd(C6F5)]. Treatment of [ClPd(μ-dpm)2Pd(C6F5)] with an excess of the ligand L, and in the presence of NaBPh4 gives the cationic complexes [LPd(μ-dpm)2Pd(C6F5)]BPh4 (L = PPh3, P(OPh)3, pyridine or tetrahydrothiophene (tht)). Reaction with isocyanides RNC leads to three different types of compounds: (a) products with the isocyanide groups inserted into the PdPd bond [(μ-RNC){;XPd(μ-dpm)2Pd(C6F5)};] (X = C6F5; R = p-tolyl; X = Cl, R = p-tolyl or Cy); (b) cationic complexes with terminal isocyanides [(RNC)Pd(μ-dpm)2Pd(C6F5)]X (X = Cl; R = t-Bu; X = BPh4, R = p-tolyl, Cy or t-Bu) and (c) complexes which contain both bridging and terminal isocyanides, [(μ-RNC){;(RNC)Pd(μ-dpm)2Pd(C6F5};BPh4] (R = p-tolyl or cyclohexyl). Addition of NaBPh4 to solutions of complexes of type a (X = Cl) results in deinsertion of the isocyanide to give complexes of type b. IR spectroscopy reveals that [(μ-CyNC){;ClPd(μ-dpm)2Pd(C6F5)};] isomerizes in CH2Cl2 to give [(CyNC)Pd(μ-dpm)2pd(C6F5)]Cl, which upon recrystallization regenerates the former complex, showing that in this case the insertion-deinsertion process is reversible.

Stereochemistry of complexes with double and triple metal-Ligand bonds: A continuous shape measures analysis

To each coordination polyhedron we can associate a normalized coordination polyhedron that retains the angular orientation of the central atom-ligand bonds but has all the vertices at the same distance from the center. The use of shape measures of these normalized coordination polyhedra provides a simple and efficient way of discriminating angular and bond distance distortions from an ideal polyhedron. In this paper we explore the applications of such an approach to analyses of several stereochemical problems. Among others, we discuss how to discern the off-center displacement of the metal from metal-ligand bond shortening distortions in families of square planar biscarbene and octahedral dioxo complexes. The normalized polyhedron approach is also shown to be very useful to understand stereochemical trends with the help of shape maps, minimal distortion pathways, and ligand association/dissociation pathways, illustrated by the Berry and anti Berry distortions of triple-bonded [X≡ML4] complexes, the square pyramidal geometries of Mo coordination polyhedra in oxido-reductases, the coordination geometries of actinyl complexes, and the tetrahedricity of heavy atom-substituted carbon centers.

Tri- and tetra-nuclear homo- or hetero-metallic palladium(II) and platinum(II) complexes with double halide bridges. Molecular structure of [NBu4]2[(C6F5)2Pt(µ-Cl)2Pt(µ-Cl)2Pt(C6F5)2]

By treating cis-[M(C6X5)2(thf)2](M = Pd or Pt, X = F or Cl, thf = tetrahydrofuran) with [M′X′4]2– or [M′2(µ-X′)2X′4]2–(M′= Pd or Pt; X′= Cl or Br) in a 2:1 ratio tri- or tetra-nuclear, homo- or heterometallic complexes of the types [NBu4]2[(C6X5)2M(µ-X′)2M′(µ-X′)2M(C6X5)2] or [NBu4]2[(C6X5)2M(µ-X′)2M′(µ-X′)2M′(µ-X′)2M(C6X5)2] can be obtained. The molecular structure of the trinuclear anion with M = M′= Pt, X = F, X′= Cl has been established by single-crystal X-ray crystallography. The anion is centrosymmetric, showing a square-planar PtCl4 central unit embraced by two Pt(C6F5)2 terminal moieties bonded to the central platinum atom through double chloride bridges.

Anionic Derivatives of Perfluorinated Trimethylgold

The homoleptic compound [PPh4 ][CF3 AuCF3 ] cleanly undergoes photoinduced oxidative addition of CF3 I to afford the organogold(III) derivative [PPh4 ][(CF3 )3 AuI] in good yield and under mild conditions. This compound provides a convenient entry to the chemistry of the perfluorinated (CF3 )3 Au fragment, the properties of which were analyzed with the aid of DFT methods and compared with those of the homologous non-fluorinated (CH3 )3 Au moiety. It was found that reductive elimination of CX3 -CX3 in the former (X=F) requires a much higher energy barrier than in the latter (X=H) and is therefore considerably less favored. This can be considered as one of the main features underlying the significantly higher stability associated to the (CF3 )3 Au fragment and its derivatives. This unsaturated, 14-electron species can be stabilized by coordination of any of the halide ligands, including fluoride. In fact, the whole series of anionic [PPh4 ][(CF3 )3 AuX] complexes (X=F, Cl, Br, I, CN) has now been isolated and conveniently characterized. Evidence for intermolecular decomposition pathways upon thermolysis in the condensed phase is presented.

Gold(I) fluorohalides: theory and experiment

The anionic trifluoromethylgold(I) derivatives [CF3 AuX]- , which have been prepared and isolated as their [PPh4 ]+ salts in good yield, undergo thermally induced difluorocarbene extrusion in the gas phase, giving rise to the mixed gold(I) fluorohalide complexes [F-Au-X]- (X=Cl, Br, I). These triatomic species have been detected by tandem mass spectrometry (MS2) experiments and their properties have been analyzed by DFT methods. The CF2 extrusion mechanism from the Au-CF3 moiety serves as a model for the CF2 insertion into the Au-F bond, since both reactivity channels are connected by the microreversibility principle.

Solid‐State and Solution Structure of a Hypervalent AX5 Compound: Sb(C6F5)5

Eliminating restraints: a trigonal-bipyramidal structure has been found to be the energetically favored geometry of the hypervalent AX(5) molecule Sb(C(6)F(5))(5) in the solid state and also in fluid solution, where molecules move freely and no crystal packing effects operate.

An Organogold(III) Difluoride with a trans Arrangement

The trans isomer of the organogold(III) difluoride complex [PPh4 ][(CF3 )2 AuF2 ] has been obtained in a stereoselective way and in excellent yield by reaction of [PPh4 ][CF3 AuCF3 ] with XeF2 under mild conditions. The compound is both thermally stable and reactive. Thus, the fluoride ligands are stereospecifically replaced by any heavier halide or by cyanide, the cyanide affording [PPh4 ][trans-(CF3 )2 Au(CN)2 ]. The organogold fluoride complexes [CF3 AuFx ]- (x=1, 2, 3) have been experimentally detected to arise upon collision-induced dissociation of the [trans-(CF3 )2 AuF2 ]- anion in the gas phase. Their structures have been calculated by DFT methods. In the isomeric forms identified for the open-shell species [CF3 AuF2 ]- , the spin density residing on the metal center is found to strongly depend on the precise stereochemistry. Based on crystallographic evidence, it is concluded that Auiii and Agiii have similar covalent radii, at least in their most common square-planar geometry.