Trifluoromethylation of [AuF3(SIMes)]: Preparation and Characterization of [Au(CF3)xF3−x(SIMes)] (x=1–3) Complexes

Trifluoromethylation of [AuF₃(SIMes)] with the Ruppert–Prakash reagent TMSCF₃ in the presence of CsF yields the product series [Au(CF₃)_xF_3−x(SIMes)] (x=1–3). The degree of trifluoromethylation is solvent dependent and the ratio of the species can be controlled by varying the stoichiometry of the reaction, as evidenced from the ¹⁹F NMR spectra of the corresponding reaction mixtures. The molecular structures in the solid state of trans-[Au(CF₃)F₂(SIMes)] and [Au(CF₃)₃(SIMes)] are presented, together with a selective route for the synthesis of the latter complex. Correlation of the calculated SIMes affinity with the carbene carbon chemical shift in the ¹³C NMR spectrum reveals that trans-[Au(CF₃)F₂(SIMes)] and [Au(CF₃)₃(SIMes)] nicely follow the trend in Lewis acidities of related organo gold(III) complexes. Furthermore, a new correlation between the Au−C_carbene bond length of the molecular structure in the solid state and the chemical shift of the carbene carbon in the ¹³C NMR spectrum is presented.     

ChemInform Abstract: Theoretical Study on Electronic Structures of AuF6 and Its Anions.

SCF-MO and CI calculations on AuFn6^- (n = 0-3) (model potential method) show that the AuF₆^- anion has the lowest minimum energy in this series and the energy of the AuF₆^3- anion is ∼ 4 eV higher than that of AuF₆^- and AuF₆^2- at their equilibrium positions.     

Th2F7[AuF4] – das erste „fluorobasische”︁ Tetrafluoroaurat(III) im System ThF4/AuF3

Th₂F₇[AuF₄] – the First Fluoroaurate in the System MF₄/AuF₃ We observed for the first time single crystals of Th₂F₇[AuF₄] [1] in attempts to synthesize ternary fluoroaurates with tetravalent cations. Concerning to X‐Ray‐data (Mo–Kα), the light‐yellow compound crystallizes tetragonal in the space group I4/mcm (No. 140) with a = 1130.6(1) pm, c = 631.34(7) pm and Z = 4.     

An Organogold(III) Difluoride with a trans Arrangement

The trans isomer of the organogold(III) difluoride complex [PPh₄][(CF₃)₂AuF₂] has been obtained in a stereoselective way and in excellent yield by reaction of [PPh₄][CF₃AuCF₃] 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)₂Au(CN)₂]. The organogold fluoride complexes [CF₃AuF_x]^? (x=1, 2, 3) have been experimentally detected to arise upon collision‐induced dissociation of the [trans‐(CF₃)₂AuF₂]^? anion in the gas phase. Their structures have been calculated by DFT methods. In the isomeric forms identified for the open‐shell species [CF₃AuF₂]^?, 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.     

Synthese und Struktur neuer Tetrafluoroaurate(III), TlF2[AuF4], M2F[AuF4]5 (M = Bi,La, Y) und Sm[AuF4]3

Synthesis and Structure of Tetrafluoroaurates(III), TlF₂[AuF₄], M₂F[AuF₄]₅ (M = Y, La, Bi), Sm[AuF₄]₃ with an Appendix on Sm[AuF₄]₂ In the system MF₃/AuF₃ the structures of several yellow Tetrafluoroaurates(III) have been determinated. TlF₂[AuF₄] crystallizes tetragonal, space group P4₁2₁2 – D (Nr. 92) with a = 573.17(4) pm, c = 2780.4(3) pm, Z = 8; M₂F[AuF₄]₅ (M = Bi, La) tetragonal, space group P4₁2₁2 – D (Nr. 92) with a = 822.89(5) pm, c = 2557.1(3) pm, Z = 4 (Bi); with a = 836.80(3) pm, c = 2602.2(2) pm, Z = 4 (La); Y₂F[AuF₄]₅ monoclin, space group P2/n – C (Nr. 13) with a = 1188.9(3) pm, b = 797.4(2) pm, c = 895.7(3) pm, β = 89.18(3), Z = 4 and Sm[AuF₄]₃ trigonal, space group R3c – D (Nr. 167) with a = 1034.5(1) pm, c = 1614.1(3) pm, Z = 6. All these yellow crystals have been obtained by solid state reactions in autoclaves or sealed goldtubes.     

Synthese und Struktur von MII[AuF4]2 (MII  Cd,Hg)

Synthesis and Structure of M^II[AuF₄]₂ (M^II ? Cd, Hg) Cd[AuF₄]₂ and the isotypic compound Hg[AuF₄]₂, both are yellow, crystallize tetragonal in the space-group P4/mcc-D (No. 124) with a = 575.0/575.6 pm, c = 1034.8/1042.3 pm and Z = 2. The single-crystals were obtained by solid-state reactions in goldtubes.     

Zur Kristallstruktur von La[AuF4]3, dem Anfangsglied der Reihe M[AuF4]3−xFx (x = 0, 0,5 und 1)

On the Crystal Structure of La[AuF₄]₃, the Final Link in the Series M[AuF₄]_3?xF_x (x = 0, 0.5 and 1) Yellow La(AuF₄)₃ was prepared for the first time in form of single crystals and investigated by X-ray methods. It crystallizes in space group R3 c-D (Nr. 167) with a = 1056.2(2) pm, c = 1633.7(8) pm, Z = 6.     

Darstellung und Struktur der Tetrafluoroaurate(III) MI[AuF4] mit MI = Li,Rb

Synthesis and Structure of Tetrafluoroaurates(III) M^I[AuF₄] with M^I = Li, Rb Single crystal investigations on Rb[AuF₄], light yellow, confirm the tetragonal unit cell (K[BrF₄]-type) with a = 618.2(1) and c = 1191(1) pm, Z = 4, space group I 4/mcm-D (No. 140). Li[AuF₄], light yellow too, crystallizes monoclinic with a = 485.32(7), b = 634.29(8), c = 1004.43(13) pm, β = 92.759(12), Z = 4; space group P 2/c-C (No. 13). The structure of Li[AuF₄] is related to the Rb[AuF₄]-type of structure.     

Synthese und Struktur von Silber(II)-tetrafluoroaurat(III) Ag[AuF4]2

Synthesis and Structure of Silver(II) Tetrafluoroaurate(III) Ag[AuF₄]₂ Intensive green single crystals of Ag[AuF₄]₂ can be obtained by heating up micro crystalline Ag[AuF₄]₂ in autoclaves (p(F₂) ～ 200 bar, T ～ 400°C, t ～ 14 d). It crystallizes monoclinic, space group P2₁/n ? C; (No. 14) with a = 522.3(1), b = 1101.3(3), c = 550.5(2) pm, β = 94.98(3), Z = 2 and is isotypic with Pd[AuF₄]₂.     

Crystal Growth and Crystal Structures of Gold(V) Compounds: Cu(AuF6)2, Ag(AuF6)2, and O2(CuF)3(AuF6)4 ⋅ HF

Crystal growth from anhydrous hydrogen fluoride solutions of M²⁺ (M=Cu, Ag) and [AuF₆]⁻ gave M(AuF₆)₂ salts (M=Cu, Ag). Similar attempts to prepare single crystals of the corresponding nickel, zinc and magnesium salts failed. The crystal structure of Cu(AuF₆)₂ consists of layers of Cu²⁺ cations connected by [AuF₆]⁻ anions, thus forming slabs. Only van der Waals interactions exist between adjacent slabs. The crystal structure of Ag(AuF₆)₂ consists of a three-dimensional framework in which Ag⁺ cations are linked by [AuF₆]⁻ anions. Both structures are members of the M^II(X^VF₆)₂ family, in which seven different structure types have been observed to date. In the crystal structure of O₂(CuF)₃(AuF₆)₄ ⋅ HF, the bridging AuF₆ units connect [−Cu−F−Cu−F−]_∞ chains to form stacks between which O₂⁺ cations and HF molecules are located.     

The Reduction of AuF3 in Super Acidic Solution

AuF₃ is reduced in superacidic HF/SbF₅ solutions giving three products. 1. Orange [Au₃F₈·2SbF₅]. It has a layered structure built up by square planar Au^IIF₄ and Au^IIIF₄ units: Crystal structure: space group P2₁/c, a = 9.049(2), b = 8.424(1), c = 9.645(1)Å, β = 115.08(1)°. 2. Black [Au₃F₇·3SbF₅] has a ribbon structure, similarly built up by square planar Au^IIF₄ and Au^IIIF₄ units: Crystal structure: space group Pc, a = 9.991(1), b = 10.728(1), c = 15.222(1)Å, β = 95.304(2)°. 3. Yellow green [(Au(HF)₂] (SbF₆)₂·2HF with square planar Au^IIF₄ units that are formed by two fluorine atoms of the anions and two HF molecules as complex ligands. Crystal structure: Space group P¯, a = 5.482(1), b = 5.848(1), c = 9.309(2)Å, α = 89.522(4), β = 85.635(4), γ = 87.509(4)°.     

The Distorted Structure of [Au(GeCl3)3]2–

It is well known that [Au(PR₃)₃]⁺ compounds (R any organic ligand) adopt a trigonal planar AuP₃ arrangement, small distortions being only due to steric repulsion between the ligands R. This is supported by relativistic MP2 geometry optimizations for the free gas phase species which yield the ideal trigonal planar AuP₃ structure for the model compound [Au(PH₃)₃]⁺. Model calculations on the recently synthesized compound [Au(GeCl₃)₃]^2– which is isoelectronic to [Au(PR₃)₃]⁺ also reveal a trigonal planar AuGe₃ structure. However, the recently determined X‐ray structure of [Au₂(dppm)₂][Au(GeCl₃)₃] shows a T‐shaped AuGe₃ arrangement. We demonstrate that this distortion is caused by solid state effects, that is the influence of the counter cations are necessary in order to obtain the observed symmetry breaking. However, unlike AuF₃ which has recently been determined by electron diffraction to be T‐shaped in the gas phase caused by a first‐order Jahn‐Teller effect, this distortion cannot be so easily rationalized by a similar AuGe₃ Jahn‐Teller effect along the e′ distortion mode. Model calculations on Na₂[Au(GeCl₃)₃] show that the strong Coulomb interaction between the negatively charged chlorine atoms and the Na⁺ ions leads to a distortion from a trigonal planar to the T‐shaped AuGe₃ arrangement lowering the energy by 137 kJ mol^–1.     

A New Class of Remote N‐Heterocyclic Carbenes with Exceptionally Strong σ‐Donor Properties: Introducing Benzo[c]quinolin‐6‐ylidene

We make the case for benzo[c]quinolin‐6‐ylidene ( 1 ) as a strongly electron‐donating carbene ligand. The facile synthesis of 6‐trifluoromethanesulfonylbenzo[c]quinolizinium trifluoromethanesulfonate ( 2 ) gives straightforward access to a useful precursor for oxidative addition to low‐valent metals, to yield the desired carbene complexes. This concept has been achieved in the case of [Mn(benzo[c]quinolin‐6‐ylidene)(CO)₅]⁺ ( 15 ) and [Pd(benzo[c]quinolin‐6‐ylidene)(PPh₃)₂(L)]²⁺ L=THF ( 21 ), OTf ( 22 ) or pyridine ( 23 ). Attempts to coordinate to nickel result in coupling products from two carbene precursor fragments. The CO IR‐stretching‐frequency data for the manganese compound suggests benzo[c]quinolin‐6‐ylidene is at least as strong a donor as any heteroatom‐stabilised carbene ligand reported.     

Investigation of Molecular Alkali Tetrafluorido Aurates by Matrix-Isolation Spectroscopy

Molecular alkali tetrafluorido aurate ion pairs M[AuF₄] (M=K, Rb, Cs) are produced by co-deposition of IR laser-ablated AuF₃ and MF in solid neon under cryogenic conditions. This method also yields molecular AuF₃ and its dimer Au₂F₆. The products are characterized by their Au–F stretching bands and high-level quantum-chemical calculations at the CCSD(T)/triple-ζ level of theory. Structural changes in AuF₄⁻ associated with the coordination of the anion to different alkali cations are proven spectroscopically and discussed.     

Vibrational spectra of AuF5 complexes with nitrogen fluorides and oxofluorides

Vibrational spectra and structural features of AuF₅ complexes with nitrogen fluorides (NF₃, N₂F₄) and oxofluorides (FNO, NF₃O) are investigated. Vibrational frequency assignment in the solid phase and in solution of anhydrous HF was made. Distinctive features of vibrational spectra of X⁺AuF₆ ^? (X = NF₄ ⁺, N₂F₃ ⁺, NO⁺, NOF₂ ⁺) related to structural transformations of cations and hexafluoroaurate anion due to the influence of the crystal field and cation-anion interactions are discussed.     

Magnetism and crystal structure of an N3O3‐coordinated iron(II) complex

The reaction of [FeL(MeOH)₂] {where L is the tetradentate N₂O₂‐coordinating Schiff base‐like ligand (E,E)‐diethyl 2,2′‐[1,2‐phenylenebis(nitrilomethylidyne)]bis(3‐oxobutanoate)(2−) and MeOH is methanol} with 3‐aminopyridine (3‐apy) in methanol results in the formation of the octahedral complex (3‐aminopyridine‐κN¹){(E,E)‐diethyl 2,2′‐[1,2‐phenylenebis(nitrilomethylidyne)]bis(3‐oxobutanoato)(2−)‐κ⁴O³,N,N′,O^3′}(methanol‐κO)iron(II), [Fe(C₂₀H₂₂N₂O₆)(C₅H₆N₂)(CH₄O)] or [FeL(3‐apy)(MeOH)], in which the Fe^II ion is centered in an N₃O₃ coordination environment with two different axial ligands. This is the first example of an octahedral complex of this multidentate ligand type with two different axial ligands, and the title compound can be considered as a precursor for a new class of complexes with potential spin‐crossover behavior. An infinite two‐dimensional hydrogen‐bond network is formed, involving the amine NH group, the methanol OH group and the carbonyl O atoms of the equatorial ligand. T‐dependent susceptibility measurements revealed that the complex remains in the high‐spin state over the entire temperature range investigated.     

An iron (II) guanidinate compound: Synthesis,characterization, thermal properties and its application as a CVD precursor for iron oxide film

An iron compound containing guanidinate ligand [Fe((SiMe₃)₂NC(ⁱPrN)₂)₂] was synthesized using a conventional lithium‐salt‐elimination reaction, and its chemical structure was characterized through elemental analysis, ¹H‐NMR and single‐crystal X‐ray diffraction, respectively. The thermal properties of the compound were examined through thermogravimetric analysis (TGA), and the TGA results demonstrated that the compound possessed sufficient volatility and suitable thermal stability for the CVD process. Moreover, the deposition experiments were conducted using the synthesized compound as a precursor and O₂ as an oxygen source to confirm its applicability as a CVD precursor, and α‐Fe₂O₃ films were successfully deposited at a relatively low deposition temperature (300°C).     

Synthesis and Catalytic Use of Gold(I) Complexes Containing a Hemilabile Phosphanylferrocene Nitrile Donor

Removal of the chloride ligand from [AuCl( 1 ‐κP)] ( 2 ) containing a P‐monodentate 1′‐(diphenylphosphanyl)‐1‐cyanoferrocene ligand ( 1 ), by using silver(I) salts affords cationic complexes of the type [Au( 1 )]X, which exist either as cyclic dimers [Au( 1 )]₂X₂ ( 3 a , X=SbF₆; 3 c , X=NTf₂) or linear coordination polymers [Au( 1 )]_nX_n ( 3 a′ , X=SbF₆; 3 b′ , X=ClO₄), depending on anion X and the isolation procedure. As demonstrated for 3 a′ , the polymers can be readily cleaved by the addition of donors, such as Cl^?, tetrahydrothiophene (tht) or 1 , giving rise to the parent compound 2 , [Au(tht)( 1 ‐κP)][SbF₆] ( 5 a ) or [Au( 1 ‐κP)₂][SbF₆] ( 4 a ), respectively, of which the last two compounds can also be prepared by stepwise replacement of tht in [Au( 1 ‐κP)₂][SbF₆]. The particular combination of a firmly coordinated (phosphane) and a dissociable (nitrile) donor moieties renders complexes 3/3′ attractive for catalysis because they can serve as shelf‐stable precursors of coordinatively unsaturated Au^I fragments, analogous to those that result from the widely used [Au(PR₃)(RCN)]X catalysts. The catalytic properties of the Au‐ 1 complexes were evaluated in model annulation reactions, such as the synthesis of 2,3‐dimethylfuran from (Z)‐3‐methylpent‐2‐en‐4‐yn‐1‐ol and oxidative cyclisation of alkynes with nitriles to produce 2,5‐disubstituted 1,3‐oxazoles. Of the compounds tested ( 2 , 3 a′ , 3 b′ , 3 a , 4 a and 5 a ), the best results were consistently achieved with dimer 3 c , which has good solubility in organic solvents and only one firmly bound donor at the gold atom. This compound was advantageously used in the key steps of annuloline and rosefuran syntheses.     

A three‐dimensional metal–organic polymer: poly[bis(μ2‐pyrimidine‐2‐thiolato‐κ4N1,S:S,N3)lead(II)]

The title compound, [Pb(C₄H₃N₂S)₂]_n, was prepared by the reaction of [Pb(OAc)₂]·3H₂O (OAc is acetate) with pyrimidine‐2‐thione in the presence of triethylamine in methanol. In the crystal structure, the Pb^II atom has an N₄S₄ coordination environment with four ligands coordinated by N‐ and S‐donor atoms. This compound shows that the pyrimidine‐2‐thiolate anion can lead to a three‐dimensional network when the coordination number of the metal ion can be higher than 6, as is the case with the Pb^II ion. This compound presents only covalent bonds, showing that despite the possibility of the hemidirected geometries of Pb^II, the eight‐coordinated ion does not allow the formation of an isolated molecular structure with pyrimidine‐2‐thiolate as the ligand.     

Stabilization of the Triphosphallyl Ligand η3‐P3{P(O)H} at Iridium via Alkaline Activation of P4

The selective functionalization of the polyphosphorus moiety Ph₂PCH₂PPh₂PPPP present as a tetrahapto‐ligand in complex [Ir(dppm)(Ph₂PCH₂PPh₂PPPP)]⁺ ( 1 , dppm=Ph₂PCH₂PPh₂) was obtained by reaction of 1 with water under basic conditions at room temperature. The formation of the new triphosphaallyl moiety η³‐P₃{P(O)H} was determined in solution by NMR spectroscopy, and confirmed in the solid state by a single‐crystal X‐ray structure of the stable product [Ir(κ²‐dppm)(κ¹‐dppm)(η³‐P₃{P(O)H})] ( 2 ). In solution, 2 has a fluxional behavior attributable to the four P atoms belonging to the tetraphosphorus moiety in 1 and exhibits a chemical exchange process involving the two PPh₂ moieties of the same bidentate ligand, as determined by 1D and 2D NMR spectroscopy experiments carried out at variable temperature. The mechanism of the reaction was investigated at the DFT level, which suggested a selective attack of an in‐situ generated OH^? anion on one of the non‐coordinated phosphorus atoms of the P₄ moiety. The reaction then evolves through an acid‐assisted tautomerization, which leads to the final compound 2 . Bonding analysis pointed out that the new unsubstituted P₃‐unit in the η³‐P₃{P(O)H} moiety behaves as a triphosphallyl ligand.