Die Pyridinaddukte der Goldhalogenide. 1. Darstellung und Struktur von [Hpy][AuCl4], AuCl3 · py, [AuCl2(py)2]Cl · H2O und [AuCl2(py)2][AuCl2]

Pyridine Adducts of the Gold Halides. 1. Synthesis and Structure of [Hpy][AuCl₄], AuC1₃ · py, [AuCl₂(py)₂]Cl · H₂O, and [AuCl₂(py)₂] [AuCl₂] HAuCl₄ reacts with pyridine in aqueous solution to form sparingly soluble [Hpy] [AuCl₄]. This goes into solution as [AuCl₂(py)₂]⁺ on adding an excess of pyridine. [Hpy][AuCl₄] decomposes above 195°C to HCl and AuCl₃ · py, which can also be obtained from NaAuCl₄ and pyridine. AuCl₂ · py is formed by the reaction of AuCl₂ · S(CH₂C₆H₄)₂ with pyridine in CHCl₃. According to the vibrational spectrum the complex is built up of trans[AuCl₂(py)₂]⁺ cations and [AuCl₂]^? anions. The IR spectra of [Hpy][AuCl₄], AuCl₃ · py, and [AuCl₂(py)₂]Cl · H₂O are discussed and assigned with respect to the crystal structures. [Hpy][AuCl₄] crystallizes monoclinic in the space group C2/m. In its structure alternating layers of [Hpy]⁺ cations and [AuCl₄]^? anions are observed. The monoclinic AuCl₃ · py (space group C2/c) consists of molecular complexes, wherein the gold atom is surrounded by three Cl atoms and one pyridine molecule in a square planar arrangement. The coordination is completed to an elongated octahedron by two more distant Cl atoms of neighbouring complexes. [AuCl₂(py)₂]Cl · H₂O crystallizes in the monoclinic space group P2₁/n. It forms planar trans[AuCl₂(py)₂]⁺ cations, weakly coordinated with an additional Cl^? ion and one H₂O molecule. The Au? Cl bond lengths in the complexes under investigation are in the range of 227 to 229 pm, the Au? N distances are between 197 and 199 pm.     

Theoretical study of the reaction of alkynes with furan catalyzed by AuCl3 and AuCl

A general scheme for the endo‐ and exo‐cyclization of furan reactivity with [L ‐Au^{III, I}Cl_x] with (x = 3, 1 and L ‐acetylene and vinylidene) complexes is investigated using density functional theory (DFT) code. Two conceivable mechanisms via a [4 + 2] Diels–Alder process or carbene complex are analyzed. According to the activation energy values of the gold (III and I) catalyst, the first mechanism, which implies the Diels–Alder reaction of Au^III, is thermodynamically favored and gives more evidence of the intramolecular addition of the furan with the alkynes. The second mechanism, presumably assisted by the spontaneous formation of the exo‐vinylidene complexes and intermediates of gold (III, I) by forming the carbene complex, is kinetically favored. Additionally, we compare our results with other structures with intramolecular additions that exhibit the quasi‐similarity of gold analogue structures. Differences in activation energies are observed, according to the functional used. Finally, we probe the solvent effects, which decrease the energy barrier in the path. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2007     

AuCl3-Catalyzed Ring-Closing Carbonyl–Olefin Metathesis

Compared with the ripeness of olefin metathesis, exploration of the construction of carbon–carbon double bonds through the catalytic carbonyl–olefin metathesis reaction remains stagnant and has received scant attention. Herein, a highly efficient AuCl₃-catalyzed intramolecular ring-closing carbonyl–olefin metathesis reaction is described. This method features easily accessible starting materials, simple operation, good functional-group tolerance and short reaction times, and provides the target cyclopentenes, polycycles, benzocarbocycles, and N-heterocycle derivatives in good to excellent yields.     

Fermi level engineering of single-walled carbon nanotubes by AuCl3 doping

We investigated the modulation of optical properties of single-walled carbon nanotubes (SWCNTs) by AuCl 3 doping. The van Hove singularity transitions (E 11 (S), E 22 (S), E 11 (M)) in absorption spectroscopy disappeared gradually with an increasing doping concentration and a new peak appeared at a high doping concentration. The work function was downshifted up to 0.42 eV by a strong charge transfer from the SWCNTs to AuCl 3 by a high level of p-doping. We propose that this large work function shift forces the Fermi level of the SWCNTs to be located deep in the valence band, i.e., highly degenerate, creating empty van Hove singularity states, and hence the work function shift invokes a new asymmetric transition in the absorption spectroscopy from a deeper level to newly generated empty states.     

35Cl NQR Spectra of the complex AuCl3SCl2

Conclusions According to the NQR spectral data, in the complex AuCl₅S the Cl atoms at the Au atom are nonequivalent, which corresponds to the structure AuCl₃(SCl₂).Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1544–1545, July, 1986.     

Development of the Pictet-Spengler reaction catalyzed by AuCl3/AgOTf

Mild and efficient AuCl3/AgOTf-catalyzed Pictet-Spengler reactions were developed to afford in good yields a variety of tetrahydroisoquinoline and tetrahydro-beta-carboline ring systems, which constitute important motifs in biologically active natural and synthetic organic compounds.     

The Lewis acidities of gold(I) and gold(III) derivatives: a theoretical study of complexes of AuCl and AuCl3

Chloride complexes of gold(I) (seventeen) and gold(III) (seventeen) with different ligands (including H, C, N, O, P, S as interacting atoms) have been studied at the CCSD(T)/CBS level. The computed geometries were compared with those found in the Cambridge Structural Database and the dissociation energies related with those previously reported in the literature by Yamamoto et al. Some special processes catalysed by these gold complexes such as bond-breaking (dihydrogen, cyclopropane) and arenes reactivity were studied in detail.

     

A package compound of a metal atom with a hydrocarbon [4][4][4][4][3](1,2,3,4,5)ferrocenophane

Perbridged ferrocenes ($\text{9}$ and $\text{11}$: the title compound) have been synthesized and characterized by spectroscopies and X-ray diffraction, and an interesting rotational disorder has been found by the X-ray crystal analyses of both $\text{9}$ and $\text{11}$.     

Synthesis of catechins via thiourea/AuCl(3)-catalyzed cycloalkylation of aryl epoxides

A diversity-oriented approach for the synthesis of structurally diverse catechins was achieved in good yields via thiourea/AuCl(3)/AgOTf-catalyzed annulations of aryl epoxides under mild conditions. This new protocol provides a highly efficient entry to a library of catechins-derived natural products, notably anti-HIV agent 8-C-ascorbyl-(-)-epigallocatechin.     

AuCl_3催化2-丙炔基-苯胺和丙炔反应机理的研究

采用密度泛函理论方法B3PW91研究了AuCl3催化剂作用下2-丙炔基-苯胺和丙炔环加成生成吲哚衍生物的反应机理。研究结果表明,吲哚衍生物的生成需要经过六个步骤,其中氢迁移过程具有最高的活化自由能为214.22 kJ/mol,是反应的速率控制步骤。整个反应是强放热的,AuCl3催化下反应能够顺利进行,而且AuCl3易于从产物上离去,所以,对于该反应AuCl3是一种有效的催化剂。     

Synthesis and Crystal Structures of [TeI3][GaI4] and [TeI3][InI4]

The compounds [TeI₃][MI₄] (M = Ga, In) were obtained as air sensitive black crystals by the reactions of Te, I₂ and Ga or In in vacuum sealed ampoules. The gallium compound crystallizes in the structural type of [SCl₃][AlCl₄]: monoclinic system, space group Pc (No. 7), a = 7.211(11), b = 7.2340(9), c = 15.67(2) Å and β = 102.51(6)°. The indium derivative crystallizes in the orthorhombic space group Pna2₁ (No. 33), a = 14.752(2), b = 7.1915(6) and c = 23.391(5) Å, with two crystallographically independent formula units per asymmetric unit. The structures consist of tetrahedral GaI₄^– or InI₄^– and trigonal pyramidal TeI₃⁺ units. Additionally, in both structures the tellurium atoms establish three weak interactions with iodine atoms of the MI₄^– units to form a distorted octahedral Te_{3 + 3} coordination sphere.     

AuCl(3)-catalyzed benzannulation: synthesis of naphthyl ketone derivatives from o-alkynylbenzaldehydes with alkynes

The reaction of o-alkynylbenzaldehydes 1 and alkynes 2 in the presence of a catalytic amount of AuCl3 in (CH2Cl)2 at 80 degrees C gave naphthyl ketone products in high yields. The AuCl3-catalyzed formal [4 + 2] benzannulation proceeds most probably through the coordination of the triple bond of 1 to AuCl3, the formation of benzo[c]pyrylium auric ate complex via the nucleophilic addition of the carbonyl oxygen atom, the Diels-Alder addition of alkynes 2 to the auric ate complex, and subsequent bond rearrangement. Similarly, the AuCl3-catalyzed reactions of o-alkynylacetophenone and o-alkynylbenzophenone with phenylacetylene afforded the corresponding naphthyl ketone products in good yields.     

Distinguishing carbones from allenes by complexation to AuCl

Quantum chemical calculations have been performed for the dicoordinated carbon compounds C(PPh(3))(2), C(NHC(Me))(2), R(2) C=C=CR(2) (R = H, F, NMe(2)), C(3)O(2), C(CN)(2)(-) and N-methyl-substituted N-heterocyclic carbene (NHC(Me)). The geometries of the complexes in which the dicoordinated carbon molecules bind as ligands to one and two AuCl moieties have been optimized and the strength and nature of the metal-ligand interactions in the mono- and diaurated complexes were investigated by means of energy decomposition analysis. The goal of the study is to elucidate the differences in the chemical behavior between carbones, allenes and carbenes. The results show that carbones bind one and two AuCl species in η(1) fashion, whereas allenes bind them in η(2) fashion. Compounds with latent divalent carbon(0) character can coordinate in more than one way, with the dominant mode indicating the degree of carbone or allene character. The calculated structures of the mono- and diaurated tetraaminoallenes (TAAs) reveal that TAAs exhibit a chameleon-like behavior: The bonding situation in the equilibrium structure is best described as allene [(R(2)N)(2)]C=C=C[(NR(2))(2)] in which the central carbon atom is a tetravalent C(IV) species, but the reactivity suggests that TAAs should be considered as divalent C(0) compounds C{C[(NR(2))(2)]}(2), that is, as "hidden" carbones. Carbon suboxide binds one AuCl preferentially in the η(1) mode, whereas the equilibrium structures of the η(1)- and η(2)-bonded diaurated complex are energetically nearly degenerate. The doubly negatively charged isoelectronic carbone C(CN)(2)(2-) binds one and two AuCl very strongly in characteristic η(1) fashion. The N-heterocyclic carbene complex, [NHC(Me)(AuCl)], possesses a high bond dissociation energy (BDE) for the splitting off of AuCl. The diaurated NHC adduct, [NHC(Me)(AuCl)(2)], has two η(1)-bonded AuCl moieties that exhibit aurophilic attraction, which yield a moderate bond strength that might be large enough for synthesizing the complex. The BDE for the second AuCl in [NHC(Me)(AuCl)(2)] is clearly smaller than the values for the second AuCl in doubly aurated carbone complexes.