Theoretical probing of deltahedral closo-auroboranes B(x)Au(x)2- (x = 5-12)

Using density functional theory calculations, here we show that a series of B(x)Au(x)2- (x = 5-12) dianions possesses structure and bonding similar to the famous deltahedral closo-borane cages, B(x)H(x)2-. Effective atomic charges on Au in B(x)Au(x)2- are very similar to those on H in B(x)H(x)2-, indicating that Au in the closo-auroboranes is indeed analogous to H in the closo-boranes. The present theoretical predictions of B(x)Au(x)2- suggest that the closo-auroborane species are viable new chemical building blocks that may be synthesized in bulk. The Au atoms in the closo-auroboranes represent highly atomically dispersed Au and may potentially exhibit novel catalytic and chemical properties.     

A photoelectron spectroscopic and computational study of sodium auride clusters, NanAun- (n = 1-3)

Negatively charged sodium auride clusters, NanAun- (n = 1-3), have been investigated experimentally using photoelectron spectroscopy and ab initio calculations. Well-resolved electronic transitions were observed in the photoelectron spectra of NanAun- (n = 1-3) at several photon energies. Very large band gaps were observed in the photoelectron spectra of the anion clusters, indicating that the corresponding neutral clusters are stable closed-shell species. Calculations show that the global minimum of Na2Au2- is a quasi-linear species with Cs symmetry. A planar isomer of D2h symmetry is found to be 0.137 eV higher in energy. The two lowest energy isomers of Na3Au3- consist of three-dimensional structures of Cs symmetry. The global minimum of Na3Au3- has a bent-flake structure lying 0.077 eV below a more compact structure. The global minima of the sodium auride clusters are confirmed by the good agreement between the calculated electron detachment energies of the anions and the measured photoelectron spectra. The global minima of neutral Na2Au2 and Na3Au3 are found to possess higher symmetries with a planar four-membered ring (D2h) and a six-membered ring (D3h) structure, respectively. The chemical bonding in the sodium auride clusters is found to be highly ionic with Au acting as the electron acceptor.     

Observation of Au2H- impurity in pure gold clusters and implications for the anomalous Au-Au distances in gold nanowires

Au(2)H(-) was recognized and confirmed as a minor contamination to typical photoelectron spectra of Au(2) (-), produced by laser vaporization of a pure Au target using an ultrahigh purity helium carrier gas. The hydrogen source was shown to be from trace H impurities present in the bulk gold target. Carefully designed experiments using H(2)- and D(2)-seeded helium carrier gas were used to study the electronic structure of Au(2)H(-) and Au(2)D(-) using photoelectron spectroscopy and density functional calculations. Well-resolved photoelectron spectra with vibrational resolution were obtained for Au(2)H(-) and Au(2)D(-). Two isomers were observed both experimentally and theoretically. The ground state of Au(2)H(-) turned out to be linear with a terminal H atom [Au-Au-H](-) ((1)A(1),C(infinity v)), whereas a linear [Au-H-Au](-) ((1)A(1),D(infinity h)) structure with a bridging H atom was found to be a minor isomer 0.6 eV higher in energy. Calculated electron detachment energies for both isomers agree well with the experimental spectra, confirming their existence in the cluster beam. The observation and confirmation of H impurity in pure gold clusters and the 3.44 A Au-Au distance in the [Au-H-Au](-) isomer presented in the current work provide indirect experimental evidence that the anomalous 3.6 A Au-Au distances observed in gold nanowires is due to an "invisible" hydrogen impurity atom.     

On the chemical bonding of gold in auro-boron oxide clusters AunBO- (n = 1-3)

During experiment on Au-B alloy clusters, an auro-boron oxide cluster Au2BO- was observed to be an intense peak dominating the Au-B mass spectra, along with weaker signals for AuBO- and Au3BO-. Well-resolved photoelectron spectra have been obtained for the three new oxide clusters, which exhibit an odd-even effect in electron affinities. Au2BO- is shown to be a closed shell molecule with a very high electron detachment energy, whereas AuBO and Au3BO neutrals are shown to be closed shell species with large HOMO-LUMO gaps, resulting in relatively low electron affinities. Density functional calculations were performed for both AunBO- (n = 1-3) and the corresponding HnBO- species to evaluate the analogy between bonding of gold and hydrogen in these clusters. The combination of experiment and theory allowed us to establish the structures and chemical bonding of these tertiary clusters. We find that the first gold atom does mimic hydrogen and interacts with the BO unit to produce a linear AuBO structure. This unit preserves its identity when interacting with additional gold atoms: a linear Au-[AuBO] complex is formed when adding one extra Au atom and two isomeric Au2-[AuBO] complexes are formed when adding two extra Au atoms. Since BO- is isoelectronic to CO, the AunBO- species can be alternatively viewed as Aun interacting with a BO- unit. The structures and chemical bonding in AunBO- are compared to those in the corresponding AunCO complexes.     

On the analogy of B-BO and B-Au chemical bonding in B11O- and B10Au- clusters

During photoelectron spectroscopy experiments, the spectra of B(11)O(-) and B(10)Au(-) clusters are found to exhibit similar patterns except for a systematic spectral shift of ～0.5 eV, hinting that they possess similar geometric structures. The electron affinities are measured to be 4.02 ± 0.04 eV for B(11)O and 3.55 ± 0.02 eV for B(10)Au. DFT calculations at the B3LYP level show that B(11)O(-) and B(10)Au(-) adopt similar C(1) ((1)A) ground states, which are based on the quasiplanar B(10) cluster interacting with a BO unit and Au, respectively. The B(11)O(-) and B(10)Au(-) clusters are thus valent isoelectronic because both BO and Au can be viewed as monovalent units, forming highly covalent B-BO and B-Au bonds analogous to the B-H bond in B(10)H(-). For B(10)Au(-), we also find a highly symmetric D(10h) ((1)A(1g)) planar molecular wheel as a minimum on the potential energy surface. However, it is 45 kcal/mol above the ground state at the B3LYP level and not viable for experimental observation. Natural bond orbital analyses reveal interesting covalent versus ionic B-Au bonding in the C(1) B(10)Au(-) and D(10h) B(10)Au(-) structures, respectively, providing insight for the design of D(nh) MB(n) molecular wheels.     

Planarization of B7- and B12- clusters by isoelectronic substitution: AlB6- and AlB11-

Small boron clusters have been shown to be planar from a series of combined photoelectron spectroscopy and theoretical studies. However, a number of boron clusters are quasiplanar, such as B(7)(-) and B(12)(-). To elucidate the nature of the nonplanarity in these clusters, we have investigated the electronic structure and chemical bonding of two isoelectronic Al-doped boron clusters, AlB(6)(-) and AlB(11)(-). Vibrationally resolved photoelectron spectra were obtained for AlB(6)(-), resulting in an accurate electron affinity (EA) for AlB(6) of 2.49 ± 0.03 eV. The photoelectron spectra of AlB(11)(-) revealed the presence of two isomers with EAs of 2.16 ± 0.03 and 2.33 ± 0.03 eV, respectively. Global minimum structures of both AlB(6)(-) and AlB(11)(-) were established from unbiased searches and comparison with the experimental data. The global minimum of AlB(6)(-) is nearly planar with a central B atom and an AlB(5) six membered ring, in contrast to that of B(7)(-), which possesses a C(2v) structure with a large distortion from planarity. Two nearly degenerate structures were found for AlB(11)(-) competing for the global minimum, in agreement with the experimental observation. One of these isomers with the lower EA can be viewed as substituting a peripheral B atom by Al in B(12)(-), which has a bowl shape with a B(9) outer ring and an out-of-plane inner B(3) triangle. The second isomer of AlB(11)(-) can be viewed as an Al atom interacting with a B(11)(-) cluster. Both isomers of AlB(11)(-) are perfectly planar. It is shown that Al substitution of a peripheral B atom in B(7)(-) and B(12)(-) induces planarization by slightly expanding the outer ring due to the larger size of Al.     

Gold derivatives of eight rare-earth-metal-rich tellurides: monoclinic R7Au2Te2 and orthorhombic R6AuTe2 types

Two series of rare-earth-metal (R) compounds, R(7)Au(2)Te(2) (R = Tb, Dy, Ho) and R(6)AuTe(2) (R = Sc, Y, Dy, Ho, Lu), have been synthesized by high-temperature techniques and characterized by X-ray diffraction analyses as monoclinic Er(7)Au(2)Te(2)-type and orthorhombic Sc(6)PdTe(2)-type structures, respectively. Single-crystal diffraction results are reported for Ho(7)Au(2)Te(2), Lu(6)AuTe(2), Sc(6)Au(0.856(2))Te(2), and Sc(6)Au(0.892(3))Te(2). The structure of Ho(7)Au(2)Te(2) consists of columns of Au-centered tricapped trigonal prisms (TCTPs) of Ho condensed into 2D zigzag sheets that are interbridged by Te and additional Ho to form the 3D network. The structure of Lu(6)AuTe(2) is built of pairs of Au-centered Lu TCTP chains condensed with double Lu octahedra in chains into 2D zigzag sheets that are separated by Te atoms. Tight binding-linear muffin-tin orbital-atomic sphere approximation electronic structure calculations on Lu(6)AuTe(2) indicate a metallic property. The principal polar Lu-Au and Lu-Te interactions constitute 75% of the total Hamilton populations, in contrast to the small values for Lu-Lu bonding even though these comprise the majority of the atoms. A comparison of the theoretical results for Lu(6)AuTe(2) with those for isotypic Lu(6)AgTe(2) and Lu(6)CuTe(2) provides clear evidence of the greater relativistic effects in the bonding of Au. The parallels and noteworthy contrasts between Ho(7)Au(2)Te(2) (35 valence electrons) and the isotypic but much electron-richer Nb(7)P(4) (55 valence electrons) are analyzed and discussed.     

Gold as hydrogen. An experimental and theoretical study of the structures and bonding in disilicon gold clusters Si2Au(n)- and Si2Au(n) (n = 2 and 4) and comparisons to Si2H2 and Si2H4

In a previous communication, we showed that a single Au atom behaves like H in its bonding to Si in a series of Si-Au clusters, SiAu(n) (n = 2-4) (Kiran et al. Angew. Chem., Int. Ed. 2004, 43, 2125). In this article, we show that the H analogy of Au is more general. We find that the chemical bonding and potential energy surfaces of two disilicon Au clusters, Si(2)Au(2) and Si(2)Au(4), are analogous to Si(2)H(2) and Si(2)H(4), respectively. Photoelectron spectroscopy and ab initio calculations are used to investigate the geometrical and electronic structures of Si(2)Au(2)(-), Si(2)Au(4)(-), and their neutral species. The most stable structures for both Si(2)Au(2) and Si(2)Au(2)(-) are found to be C(2)(v), in which each Au bridges the two Si atoms. For Si(2)Au(4)(-), two nearly degenerate dibridged structures in a cis (C(2)(h)) and a trans (C(2)(v)) configuration are found to be the most stable isomers. However, in the neural potential energy surface of Si(2)Au(4), a monobridged isomer is the global minimum. The ground-state structures of Si(2)Au(2)(-) and Si(2)Au(4)(-) are confirmed by comparing the computed vertical detachment energies with the experimental data. The various stable isomers found for Si(2)Au(2) and Si(2)Au(4) are similar to those known for Si(2)H(2) and Si(2)H(4), respectively. Geometrical and electronic structure comparisons with the corresponding silicon hydrides are made to further establish the isolobal analogy between a gold atom and a hydrogen atom.     

A photoelectron spectroscopic and theoretical study of B16- and B16(2-): an all-boron naphthalene

The structure and chemical bonding of B16- were studied using ab initio calculations and photoelectron spectroscopy. Its global minimum is found to be a quasi-planar and elongated structure (C2h). Addition of an electron to B16- resulted in a perfectly planar and closed shell B16(2-) (D2h), which is shown to possess 10 pi electrons with a pi-bonding pattern similar to that of naphthalene and can thus be considered as an "all-boron naphthalene", a new member in the growing family of hydrocarbon analogues of boron clusters.     

Relativistic effects and gold site distributions: synthesis, structure, and bonding in a polar intermetallic Na6Cd16Au7

Na(6)Cd(16)Au(7) has been synthesized via typical high-temperature reactions, and its structure refined by single crystal X-ray diffraction as cubic, Fm ?3m, a = 13.589(1) ?, Z = 4. The structure consists of Cd(8) tetrahedral star (TS) building blocks that are face capped by six shared gold (Au2) vertexes and further diagonally bridged via Au1 to generate an orthogonal, three-dimensional framework [Cd(8)(Au2)(6/2)(Au1)(4/8)], an ordered ternary derivative of Mn(6)Th(23). Linear muffin-tin-orbital (LMTO)-atomic sphere approximation (ASA) electronic structure calculations indicate that Na(6)Cd(16)Au(7) is metallic and that ～76% of the total crystal orbital Hamilton populations (-ICOHP) originate from polar Cd-Au bonding with 18% more from fewer Cd-Cd contacts. Na(6)Cd(16)Au(7) (45 valence electron count (vec)) is isotypic with the older electron-richer Mg(6)Cu(16)Si(7) (56 vec) in which the atom types are switched and bonding characteristics among the network elements are altered considerably (Si for Au, Cu for Cd, Mg for Na). The earlier and more electronegative element Au now occupies the Si site, in accord with the larger relativistic bonding contributions from polar Cd-Au versus Cu-Si bonds with the neighboring Cd in the former Cu positions. Substantial electronic differences in partial densities-of-states (PDOS) and COHP data for all atoms emphasize these. Strong contributions of nearby Au 5d(10) to bonding states without altering the formal vec are the likely origin of these effects.     

Probing the electronic structure and chemical bonding of gold oxides and sulfides in AuOn(-) and AuSn(-) (n = 1, 2)

The Au-O and Au-S interactions are essential in nanogold catalysis and nanotechnology, for which monogold oxide and sulfide clusters serve as the simplest molecular models. We report a combined photoelectron spectroscopy and ab initio study on AuO (-) and AuO 2 (-) and their valent isoelectronic AuS (-) and AuS 2 (-) species to probe their electronic structure and to elucidate the Au-O and Au-S chemical bonding. Vibrationally resolved spectra were obtained at different photon energies, providing a wealth of electronic structure information for each species. Similar spectra were observed for AuO (-) and AuS (-) and for the linear OAuO (-) and SAuS (-) species. A bent isomer was also observed as Au(S 2) (-) in the AuS 2 (-) spectra, whereas a similar Au(O 2) (-) complex was not observed in the case of AuO 2 (-). High-level ab initio calculations were conducted to aid spectral assignments and provide insight into the chemical bonding in the AuX (-) and AuX 2 (-) molecules. Excellent agreement is achieved between the calculated electronic excitations and the observed spectra. Configuration interactions and spin-orbit couplings were shown to be important and were necessary to achieve good agreement between theory and experiment. Strong covalent bonding was found in both the AuX (-) and the XAuX (-) species with multiple bonding characters. While Au(S 2) (-) was found to be a low-lying isomer with a significant binding energy, Au(O 2) (-) was shown to be unbound consistent with the experimental observation. The latter is understood in the context of the size-dependent reactivity of Au n (-) clusters with O 2.     

A photoelectron spectroscopy and ab initio study of B21-: negatively charged boron clusters continue to be planar at 21

The structures and chemical bonding of the B(21)(-) cluster have been investigated by a combined photoelectron spectroscopy and ab initio study. The photoelectron spectrum at 193 nm revealed a very high adiabatic electron binding energy of 4.38 eV for B(21)(-) and a congested spectral pattern. Extensive global minimum searches were conducted using two different methods, followed by high-level calculations of the low-lying isomers. The global minimum of B(21)(-) was found to be a quasiplanar structure with the next low-lying planar isomer only 1.9 kcal/mol higher in energy at the CCSD(T)/6-311-G* level of theory. The calculated vertical detachment energies for the two isomers were found to be in good agreement with the experimental spectrum, suggesting that they were both present experimentally and contributed to the observed spectrum. Chemical bonding analyses showed that both isomers consist of a 14-atom periphery, which is bonded by classical two-center two-electron bonds, and seven interior atoms in the planar structures. A localized two-center two-electron bond is found in the interior of the two planar isomers, in addition to delocalized multi-center σ and π bonds. The structures and the delocalized bonding of the two lowest lying isomers of B(21)(-) were found to be similar to those in the two lowest energy isomers in B(19)(-).     

Photoelectron spectroscopy and ab initio study of the doubly antiaromatic B(6) (2-) dianion in the LiB(6) (-) cluster

A metal-boron mixed cluster LiB(6) (-) was produced and characterized by photoelectron spectroscopy and ab initio calculations. A number of electronic transitions were observed and used to compare with theoretical calculations. An extensive search for the global minimum of LiB(6) (-) was carried out via an ab initio genetic algorithm technique. The pyramidal C(2v) ((1)A(1)) molecule was found to be the most stable at all levels of theory. The nearest low-lying isomer was found to be a triplet C(2) ((3)B) structure, 9.2 kcal/mol higher in energy. Comparison of calculated detachment transitions from LiB(6) (-) and the experimental photoelectron spectra confirmed the C(2v) pyramidal global minimum structure. Natural population calculation revealed that LiB(6) (-) is a charge-transfer complex, Li(+)B(6) (2-), in which Li(+) and B(6) (2-) interact in a primarily ionic manner. Analyses of the molecular orbitals and chemical bonding of B(6) (2-) showed that the planar cluster is twofold (pi- and sigma-) antiaromatic, which can be viewed as the fusion of two aromatic B(3) (-) units.     

Probing the structures and chemical bonding of boron-boronyl clusters using photoelectron spectroscopy and computational chemistry: B(4)(BO)(n) (-) (n = 1-3)

The electronic and structural properties of a series of boron oxide clusters, B(5)O(-), B(6)O(2) (-), and B(7)O(3) (-), are studied using photoelectron spectroscopy and density functional calculations. Vibrationally resolved photoelectron spectra are obtained, yielding electron affinities of 3.45, 3.54, and 4.94 eV for the corresponding neutrals, B(5)O, B(6)O(2), and B(7)O(3), respectively. Structural optimizations show that these oxide clusters can be formulated as B(4)(BO)(n) (-) (n = 1-3), which involve boronyls coordinated to a planar rhombic B(4) cluster. Chemical bonding analyses indicate that the B(4)(BO)(n) (-) clusters are all aromatic species with two π electrons.     

OH(3) (-) and O(2)H(5) (-) double Rydberg anions: predictions and comparisons with NH(4) (-) and N(2)H(7) (-)

A low barrier in the reaction pathway between the double Rydberg isomer of OH(3) (-) and a hydride-water complex indicates that the former species is more difficult to isolate and characterize through anion photoelectron spectroscopy than the well known double Rydberg anion (DRA), tetrahedral NH(4) (-). Electron propagator calculations of vertical electron detachment energies (VEDEs) and isosurface plots of the electron localization function disclose that the transition state's electronic structure more closely resembles that of the DRA than that of the hydride-water complex. Possible stabilization of the OH(3) (-) DRA through hydrogen bonding or ion-dipole interactions is examined through calculations on O(2)H(5) (-) species. Three O(2)H(5) (-) minima with H(-)(H(2)O)(2), hydrogen-bridged, and DRA-molecule structures resemble previously discovered N(2)H(7) (-) species and have well separated VEDEs that may be observable in anion photoelectron spectra.     

Observation of a mixed-metal transition in heterobimetallic Au/Ag dicyanide systems

Crystals of the mixed-metal heterobimetallic Au/Ag dicyanide complex, K[AuxAg1-x(CN)2] (x = 0-->1), were obtained by slow evaporation. The mixed-metal complex K[Au0.44Ag0.56(CN)2] crystallizes in a rhombohedral crystal system, space group R. The crystal structure consists of layers of linear chains of Au(CN)2- and Ag(CN)2- ions and K+ ions that connect the layers through the N atoms. The excitation and emission spectra of single crystals of K[AuxAg1-x(CN)2] were recorded at 4.2-180 K using excitation wavelengths between 230 and 260 nm. Two emission bands due to Ag-Au interactions were observed at 343 and 372 nm. Lifetime measurements indicate the shorter-wavelength emission corresponds to fluorescence and the longer-wavelength band is phosphorescence. These new emission bands are not seen in the pure K[Ag(CN)2] or pure K[Au(CN)2] crystals. Extended Hückel calculations show that the LUMO of the mixed-metal system is bonding while the HOMO is antibonding or very weakly bonding. Moreover, excited-state extended Hückel calculations indicate the formation of exciplexes with shorter metal-metal distances and higher metal-metal overlap populations than the corresponding ground-state oligomers. The luminescence is assigned to a mixed-metal transition from a molecular orbital with Au character to a molecular orbital with Ag character.     

Valence isoelectronic substitution in the B8(-) and B9(-) molecular wheels by an Al dopant atom: umbrella-like structures of AlB7(-) and AlB8(-)

The structures and the electronic properties of two aluminum-doped boron clusters, AlB(7)(-) and AlB(8)(-), were investigated using photoelectron spectroscopy and ab initio calculations. The photoelectron spectra of AlB(7)(-) and AlB(8)(-) are both broad, suggesting significant geometry changes between the ground states of the anions and the neutrals. Unbiased global minimum searches were carried out and the calculated vertical electron detachment energies were used to compare with the experimental data. We found that the Al atom does not simply replace a B atom in the parent B(8)(-) and B(9)(-) planar clusters in AlB(7)(-) and AlB(8)(-). Instead, the global minima of the two doped-clusters are of umbrella shapes, featuring an Al atom interacting ionically with a hexagonal and heptagonal pyramidal B(7) (C(6v)) and B(8) (C(7v)) fragment, respectively. These unique umbrella-type structures are understood on the basis of the special stability of the quasi-planar B(7)(3-) and planar B(8)(2-) molecular wheels derived from double aromaticity.     

H2O nucleation around Au+

First principles electronic structure calculations have been carried out to investigate the ground state geometry, electronic structure, and the binding energy of [Au(H2O)n]+ clusters containing up to 10 H2O molecules. It is shown that the first coordination shell of Au+ contains two H2O molecules forming a H2O-Au+-H2O structure with C2 symmetry. Subsequent H2O molecules bind to the previous H2O molecules forming stable and fairly rigid rings, each composed of 4 H2O molecules, and leading to a dumbbell structure at [Au(H2O)8]+. The 9th and the 10th H2O molecules occupy locations above the Au+ cation mainly bonded to one H2O from each ring, leading to structures where the side rings are partially distorted and forming structures that resemble droplet formation around the Au+ cation. The investigations highlight quantum effects in nucleation at small sizes and provide a microscopic understanding of the observed incremental binding energy deduced from collision induced dissociation that indicates that [Au(H2O)n]+ clusters with 7-10 H2O molecules have comparable binding energy. The charge on the Au+ is shown to migrate to the outside H2O molecules, suggesting an interesting screening phenomenon.     

Toward rational construction of gold, gold-silver, and gold-mercury string complexes: syntheses, structures, and properties of [Au(Tab)2]2L2 (L = I and PF6), {[(Tab)2M][Au(CN)2]}2 (M = Au and Ag), and {[Hg(Tab)2][Au(CN)2]2} [Tab = 4-(trimethylammonio)benzenethiolate

The reaction of AuI with 2 equiv of TabHPF6 [TabH = 4-(trimethylammonio)benzenethiol] in the presence of excess Et3N in dimethylformamide (DMF)/MeOH afforded a binuclear gold(I) complex [Au(Tab)2]2I2.2H2O (1). Anion exchange of 1 with NH4PF6 in DMF gave rise to the more soluble complex [Au(Tab)2]2(PF6)2 (2). Treatment of 2 with K[Au(CN)2] produced a tetranuclear gold(I) complex {[(Tab)2Au][Au(CN)2]}2 (3). Analogous reactions of two known mononuclear complexes [Ag(Tab)2](PF6) (4) and [Hg(Tab)2](PF6)2 (5) with 1 or 2 equiv of K[Au(CN)2] generated one Ag2Au2 complex {[(Tab)2Ag][Au(CN)2]}2 (6) and one Au/Hg complex {[Hg(Tab)2][Au(CN)2]2} (7), respectively. Compounds 1-3, 6, and 7 were fully characterized by elemental analysis, IR spectra, UV-vis spectra, 1H NMR, and single-crystal X-ray crystallography. 1 and 2 have a similar [Au(Tab)2]2(2+) dimeric structure in which the two [Au(Tab)2]+ cations are connected via one Au-Au aurophilic interaction. In the structure of 3 or 6, each of the two pairs of [M(Tab)2]+ cation and [Au(CN)2]- anion is held together via ionic interactions to form a {[(Tab)2M][Au(CN)2]} species (M = Au, 3; Ag, 6). Two such species are further connected by one Au-Au aurophilic bonding interaction to form an uncommon Au(4) or Ag2Au2 linear string structure with three ligand-unsupported metal-metal bonds. For 7, the [Hg(Tab)2]2+ dication and the [Au(CN)2]2(2-) dianion are interconnected by the secondary Hg...N(CN) interactions to form a 1D chain structure. The thermal and luminescent properties of 1-3, 6, and 7 in solid state were also investigated.     

Au(II)化合物[Au(CH2)2PH2]2X2 (X＝F, Cl, Br, I)的量子化学理论研究

采用从头计算HF, MP2方法和密度泛函理论, 对Au(II)系列化合物[Au(CH₂)₂PH₂]₂X₂ (X＝F, Cl, Br, I)的几何结构、电子结构和振动频率进行了研究. 研究表明Au的5d和6s电子参与Au—Au以及Au—X之间的成键. Au—Au, Au—X键强烈的电子相关作用使HF方法不适于该体系的研究, BP86和B3LYP两种泛函给出较大的Au—Au和Au—X键长, 而MP2方法和局域的密度泛函方法则给出了合理的结构参数. 局域密度泛函方法计算得到的Au—Au键和 Au—X键振动频率也与实验数据符合较好. 还运用含时密度泛函理论计算了[Au(CH₂)₂PH₂]₂X₂的电子激发能, 对分子在紫外-可见光谱范围内的电子跃迁进行了分析, 考察了卤素配体对激发能的影响, 并结合分子轨道能级的变化对此给予了解释.