Trinuclear Gold Complexes Research Articles

Exploring the bonding and aromaticity of [Au3{C2H2N2E(L)2}3]+ (E = Si, Ge and L = –CH3, -H, -CF3, –NO2): Trinuclear gold superalkali complexes

Coinage metal [Cu, Ag, Au] complexes, with carbene analogous ligands, especially silylene, and germylene, have been getting attention in recent years for their potential applications, either in homogeneous catalysis or in photophysical properties. In this study, we have designed trinuclear gold complexes with different substituted silylene and germylene and observed that these trinuclear gold complexes are stable in cationic form and behave like a superalkali. Conceptual density functional theory (CDFT) based descriptors like electrophilicity give the idea about the reactivity of these superalkali complexes. Negative NICS values determine the aromatic nature of the trinuclear core of these complexes. Atom in molecules (AIM) study has been performed to gain a clear idea about the bonding nature of complexes. Energy decomposition analysis (EDA) suggests that electrostatic interaction stabilizes the complex. First-order hyperpolarizability calculation confirms their high nonlinear optical (NLO) properties.

Back Cover: Di- and Trinuclear Gold Complexes of Diphenylphosphinoethyl-Functionalised Imidazolium Salts and their N-Heterocyclic Carbenes: Synthesis and Photophysical Properties (Chem. Eur. J. 2/2015)

Back Cover: Di- and Trinuclear Gold Complexes of Diphenylphosphinoethyl-Functionalised Imidazolium Salts and their N-Heterocyclic Carbenes: Synthesis and Photophysical Properties (Chem. Eur. J. 2/2015)

Dispersion, solvent and metal effects in the binding of gold cations to alkynyl ligands: implications for Au(I) catalysis.

The coordination modes of the [Au(PPh3)](+) cation to metal alkynyl complexes have been investigated. On addition to ruthenium, a vinylidene complex, [Ru(η(5)-C5H5)(PPh3)2([double bond, length as m-dash]C[double bond, length as m-dash]CPh{AuPPh3})](+), is obtained while addition to a gold(iii) compound gives di- and trinuclear gold complexes depending on the conditions employed. In the trinuclear species, a gold(i) cation is sandwiched between two gold(iii) alkynyl complexes, suggesting that coordination of multiple C-C triple bonds to gold is facile.

Di- and trinuclear gold complexes of diphenylphosphinoethyl-functionalised imidazolium salts and their N-heterocyclic carbenes: synthesis and photophysical properties.

Diphenylphosphinoethyl-functionalised imidazolium salts and their silver-carbene complexes were used to synthesise a series of di- and trinuclear gold complexes through ligand exchange and transmetallation, respectively. Besides a few positively charged macrocyclic compounds with different anions (both with and without activation of the carbene function), we were able to obtain neutral polynuclear complexes by varying the gold precursor. The synthesised gold complexes show a variety of photophysical properties, including bright white photoluminescence at ambient temperature.

N-heterocyclic carbene stabilized phosphaalkenyl(chloro)stannylene

The new phosphaalkenyl(chloro)tin(II) compound NHC-Sn(Cl)[C(SiMe3)=PMes*] was isolated and fully characterized including molecular structure determination by a single crystal X-ray diffraction analysis. Its reaction with Me2SAuCl led to the formation of an unprecedented P=C-bridged trinuclear gold complex [AuC(SiMe3)=PMes*]3 through the transfer of the phosphaalkenyl substituent to the gold atom.

Planar tris-N-heterocyclic carbenes

To further explore the coordination chemistry of poly-carbene complexes, two triphenylene-based planar tridentate N-heterocyclic carbenes and their corresponding tri-gold complexes were synthesized. Molecular structures of the tert-butyl substituted tritopic free carbene and the tri-nuclear gold complex were determined experimentally. A silver-dicarbene organometallic polymer was also prepared with the newly synthesized tris-NHC.

Luminescent heterometallic gold–copper alkynyl complexes stabilized by tridentate phosphine

The reactions between trinuclear gold complex tppmAu(3)Cl(3) (tppm = tris(diphenylphosphino)methane), arylacetylenes HC(2)C(6)H(4)X and Cu(+) under basic conditions result in formation of the heterometallic complexes [tppm(AuC(2)C(6)H(4)X)(3)Cu](+), X = H (1), COOMe (2), CN (3), OMe (4), NH(2) (5). These compounds belong to one structural motif and consist of the heterometallic {(AuC(2)C(6)H(4)X)(3)Cu} core stabilized by the tridentate phosphine. Compounds 1-5 were characterized by polynuclear NMR and IR spectroscopy, ESI-MS and single-crystal X-ray analysis. Luminescence properties of these complexes have been studied and revealed a substantial red shift of the emission maxima with the increase in the electron donicity of the alkynyl ligands substituents in the 550-680 nm range. The theoretical calculations of the electronic structures showed that variations of the substituents on the alkynyl ligands display very little effect on the molecular structural parameters but show appreciable influence on the orbital energies and luminescence characteristics of the compounds under study.

Salt‐like Structures of Oligomeric Gold Complexes and Polyoxometalates

AbstractBy cleaving large gold clusters, dimeric and trimeric cationic gold complexes were generated and combined with polyoxometalates to form salt‐like intercluster compounds. Four of them comprise binuclear gold complexes [Au2(dppx)2]2+ with dppx = Ph2P(CH2)nPPh2 with n = 1–3. Short chain lengths with n = 1 and 2, respectively, either enforce, or allow for short gold–gold distances. With n = 3 the gold atoms are kept at distances not allowing significant metallophilic interactions. The overall packing of these compounds can be related to the anti‐As2O3, CsCl, anti‐CaCl2 type. (nBu4N)2[Au3dppm2Cl2][PW12O40] contains a trinuclear gold complex and realizes a distorted Li3Bi‐type of topology.

Intermolecular aurophilic interactions facilitate assembly of a complex rotaxane in solution

We describe the formation of a complex [2]rotaxane both in solution and in the solid state. The rotaxane ring is composed of a cyclic trinuclear gold complex and the Au(PMe(3))(2)(+) rod is held in place by three aurophilic interactions to the ring Au atoms. The existence of the [2]rotaxane in solution is confirmed by VT-NMR and MS analysis.

Preparation, Structure and Gold(I) Complexation of p-Xylylene-1,4-diphosphines

1,4-Dimethyl-2,5-di(phosphinyl)benzene (1) was prepared in high yield in a four-step synthesis from 1,4-dibromo-2,5-dimethyl-benzene. The intermediates with (Et2N)2P and Cl2P groups (2, 3) with the corresponding substitution pattern have been isolated and structurally characterized. All three compounds (1 - 3) adopt a centrosymmetrical conformation with one of the P-X bonds of each X2P group located in the ring plane while the other reaches out from this plane in a roughly perpendicular orientation. Distortions of the ring and its substituents from a standard planar hexagonal geometry are readily explained by invoking steric and inductive effects. The crystal structure of 1,4-dibromo-2,5-dimethyl-benzene has also been determined for reference purposes. Compound 1 was employed as a substrate for auration by tri(gold)oxonium salts of the type {[(R3P)Au]3O}BF4. Hexanuclear complex salts of the type {[(R3P)Au]3P(C6H2Me2)P[Au(PR3)]3}(BF4)2 were obtained in almost quantitative yield with R3P = tBu3P (4) and Ph3P (5). The former (4) has the higher thermal stability, it could be crystallized and its structure determined. It features a conformation in which the xylene plane bisects one of the Au-P-Au angles at both tetrahedrally coordinated central phosphorus atoms placing its methyl groups in sterically least hindered positions. Compound 5 is labile in solution and shows rapid ligand exchange on the NMR time scale. The limited stability has also been confirmed by mass spectrometry. Similar structural details and differences in stability were observed in the related trinuclear gold complexes based on 1-naphthyl-phosphine, which were prepared as reference materials using the same preparative procedure. Of the two compounds {(1-C10H7)- P[Au(PR3)]3}BF4, with R3P = tBu3P (6) and Ph3P (7), the former is the more stable species. In the solid state the cation approaches mirror symmetry in a conformation comparable to that of 4. Compound 7 is thermally labile and shows a rapid ligand exchange in solution.

Aurophilicity-based one-dimensional arrays of gold(I) phenylene-1,3- and -1,4-dithiolates.

Phenylene-1,3-dithiol is converted into a trinuclear gold complex by treatment with 1 equiv of [[(Ph(3)P)Au](3)O](+)BF(4)(-). In the product, the phenylene unit bears one gold thiolate and one di(gold)sulfonium function. These components aggregate into one-dimensional arrays through head-to-tail aurophilic contacts between the two functions. In the association process, the Au[bond]S[bond]Au angle of the sulfonium group is opened up to accommodate the incoming gold atom between its metal centers. A similar mode of aggregation is found for the triply aurated biphenylene-4,4'-dithiol obtained using the tri(gold)oxonium salt with tri(p-tolyl)phosphine ligands. Probably for steric reasons, in this oligomerization process, the gold(I) thiolate unit is attached side-on to the digold sulfonium unit with retention of the small Au[bond]S[bond]Au angle. Under similar reaction conditions, and with the same molar ratio of the components, phenylene-1,4-dithiol is converted into the bis-sulfonium salt: 1,4-[[(p-Tol)(3)PAu](2)S](2)C(6)H(4)(BF(4))(2), the dications of which also associate into chains. Along the chains, the phenylene spacers alternate with tetranuclear gold clusters which arise from intimate aggregation of pairs of gold atoms. Together with previous findings, the present results show that gold thiolate (-SAuL) and digold sulfonium functions [-S(AuL)(2)(+)] in proper orientation at an arene unit (alpha-omega) can be considered as "soldering" points which can be used for joining up the molecular units into one-dimensional arrays solely through metal-metal contacts, which appear to be operative even against Coulomb repulsion between cations. The reaction of biphenylene-4,4'-dithiol with 2 equiv of sodium methoxide and [tri(c-hexyl)phosphine]gold chloride gives only neutral digold dithiolate complex 4 which is not associated owing to the steric bulk of the tri(c-hexyl)phosphine ligands.

Supramolecular Chain Assemblies Formed by Interaction of a π Molecular Acid Complex of Mercury with π-Base Trinuclear Gold Complexes

Dipartimento di Scienze Chimiche dell’ UniVersita`Via S. Agostino 1, I-62032 Camerino, ItalyDepartment of Chemistry and Laboratory for MolecularStructure and Bonding, Texas A&M UniVersityCollege Station, Texas 77843Department of Chemistry and Chemical BiologyHarVard UniVersity, 12 Oxford StreetCambridge, Massachusetts 02138ReceiVed July 11, 2000The trinuclear cyclic Au

Theoretical study of the electronic structure and luminescence of trinuclear gold complex

The luminescence of the trimeric organometallic complex [Au 3(CH 3NCOCH 3) 3] in solution has been reported recently. To explain this phenomenon, we have carried out theoretical calculations of the complex in gas phase and in chloroform solution at B3LYP/6-31++G level. The calculated structure and the vibrational frequencies are in good agreement with the experimental results. Calculation of the triplet as the excited state gives an emission transition equal to 2.34 eV in gas phase and 2.36 eV in solution. With these results, a possible explanation of the luminescence of this compound is given.

Synthesis, Structure, Luminescence, and Raman-Determined Excited State Distortions of a Trinuclear Gold(I) Phosphine Thiolate Complex

The synthesis, crystal structure and spectroscopic properties of a new luminescent trinuclear gold complex, bis(triethylphosphine)gold(I) [μ-(1,1-dicyanoethylene-2,2-dithiolato-1κS:2κS‘)][μ-(1,1-dicyanoethylene-2,2-dithiolato-2κS2:3κS‘)](triethylphosphine-1κP)(triethylphosphine-3κP)triaurate(I), 1, are reported. The structure contains a linear array of three gold atoms, the central gold on an inversion center. 1 crystallizes in the P21/n space group with a = 13.681(1) A, b = 11.433(1) A, c = 15.608(1) A, β = 106.93(1)°, V=2335.4(3) A3, and Z = 2. The luminescence spectrum is centered at 19 600 cm-1 and displays poorly resolved vibronic structure with a spacing of 470 cm-1, characteristic of a normal mode primarily Au−S in character. The transition is assigned to a dithiolate to gold charge transfer. The vibrational frequencies and intensities obtained from the preresonance Raman spectra are used to calculate the distortions the molecule undergoes when excited to its emissive charge transfer excited state....

Ylide Transfer Reactions Used for the Synthesis of Di- and Trinuclear Gold Complexes. X-ray Structure of [Au3(.mu.2-CH2PPh2CH2)2(PPh3)2]TCNQ (TCNQ = 7,7',8,8'-Tetracyanoquinodimethane)

Ylide Transfer Reactions Used for the Synthesis of Di- and Trinuclear Gold Complexes. X-ray Structure of [Au3(.mu.2-CH2PPh2CH2)2(PPh3)2]TCNQ (TCNQ = 7,7',8,8'-Tetracyanoquinodimethane)