金纳米颗粒在不同包裹介质中的超快等离子体动力学

Herein, we prepared four samples, namely gold/poly(sodium-p-styrenesulfonate) (Au/PSS), gold/silicon dioxide (Au/SiO₂), gold/titanium dioxide (Au/TiO₂), and gold/cuprous oxide (Au/Cu₂O) core/shell nanocomposites, to investigate how the surrounding medium affects the ultrafast plasmon dynamics of Au nanoparticles (NPs). We recorded femtosecond transient absorption spectra of Au NPs in Au/PSS, Au/SiO₂, Au/TiO₂, and Au/Cu₂O core/shell nanocomposites at various time delays. We found that the spectral features in the femtosecond transient absorption spectra of Au NPs in Au/TiO₂ and Au/Cu₂O core/shell nanocomposites were dramatically different from those of Au NPs in Au/PSS and Au/SiO₂ core/shell nanocomposites. A comprehensive analysis of the ultrafast plasmon dynamics of Au NPs in the core/shell nanocomposites revealed that following excitation of the resonance plasmon band of Au NPs, the exited electrons could be efficiently transferred into the conduction bands of TiO₂ and Cu₂O in Au/TiO₂ and Au/Cu₂O core/shell nanocomposites.     

银/金纳米线阵列表面增强拉曼基底的制备及对孔雀石绿的高灵敏度检测

利用种子介导的软模板生长方法制备了金纳米线(Au NWs)阵列, 通过调节生长温度控制Au NWs阵列的形貌, 最后在经硼氢化钠(NaBH₄)清洗过的Au NWs阵列上化学沉积银纳米颗粒(Ag NPs), 制得银/金纳米线(Ag/Au NWs)阵列作为表面增强拉曼散射(SERS)基底. 选用罗丹明6G(R6G)作为拉曼探针分子测定了Ag/Au NWs阵列的SERS性能. 结果表明, Ag/Au NWs阵列作为SERS基底具有高灵敏度、 优异的信号均匀性和良好的稳定性. 使用Ag/Au NWs阵列对孔雀石绿(MG)检测的检出限可低至1×10^-8 mol/L, 线性范围为 1×10^-8~1×10^-4 mol/L. NaBH₄可以在不影响SERS性能的情况下去除Ag/Au NWs阵列上吸附的分子, 使得 SERS基底可以重复使用. 使用Ag/Au NWs阵列对湖水中的MG进行检测, 得到了可靠的回收率, 证明Ag/Au NWs 阵列在检测环境水体中的孔雀石绿上具有应用潜力.     

L-半胱氨酸改性Fe3O4纳米粒子的水热合成及其应用

以L-半胱氨酸为表面改性剂与粒径调节剂,采用水热法制备具有良好分散稳定性的磁性Fe₃O₄纳米粒子。通过透射电镜（TEM）、扫描电镜（SEM）、X射线衍射仪（XRD）、比磁饱和强度测定仪（VSM）等对产物进行表征,研究L-半胱氨酸对磁性Fe₃O₄纳米粒子的形貌、粒径分布、晶型结构、分散稳定性等的影响,理论推导了L-半胱氨酸改性后的Fe₃O₄纳米粒子（L-Fe₃O₄纳米粒子）的生成机制,将该材料作为载体吸附金种后探讨其在催化对硝基苯酚方面的应用。结果表明：沉降22 h时,调节pH值为7.0制备的Fe₃O₄纳米粒子的沉降高度大约是L-Fe₃O₄纳米粒子的6.5倍;吸附金种后的L-Fe₃O₄纳米粒子催化效率大约是未改性Fe₃O₄纳米粒子的5倍。L-半胱氨酸有效的改善了Fe₃O₄纳米粒子与分散介质之间的相容性,保护并改善了纳米粒子的分散稳定性,在污水处理等方面有潜在的应用。     

Polypyrrole Hollow Nanotubes Loaded with Au and Fe3O4 Nanoparticles for Simultaneous Determination of Ascorbic Acid,Dopamine, and Uric Acid

An ultrasensitive electrochemical biosensor was fabricated for electroanalytical determination of ascorbic acid(AA), dopamine(DA) and uric acid(UA) individually and simultaneously based on polypyrrole hollow nanotubes loaded with Au and Fe₃O₄ nanoparticles(NPs) uniformly(PPy@Au-Fe₃O₄). The PPy@Au-Fe₃O₄ nanotubes were synthesized in one-pot using MoO₃ nanorods as templates and the polymerization of Py, the formation of Au and Fe₃O₄ NPs and the removel of MoO₃ templates took place stimultaneously. Electrochemical studies reveal that PPy@Au-Fe₃O₄modified glassy carbon electrode(GCE) possesses excellent electro-catalytic activities toward the oxidation of AA, DA and UA. Their oxidation peak currents increase linearly in the concentration ranges of 1-2000 μmol/L for AA, 0.01-25 and 25-300 μmol/L for DA and 0.1-300 μmol/L for UA. Their detection limit values(S/N=3) were calculated as 0.45, 0.0049, and 0.051 μmol/L for AA, DA and UA in the individual detection. By changing the concentrations simultaneously, the calibration curves showed linearity to 1000, 200, and 200 μmol/L with detection limit of 0.39, 0.0060, and 0.060 μmol/L for AA, DA, and UA, respectively. Finally, the obtained biosensor was successfully applied to the detection of AA, DA, and UA with satisfactory results on actual samples.     

Z型可见光催化剂Au NPs/g-C3N4/BiOBr的构建及其光催化性能

通过水热和原位还原法制备了一种新型Z型异质结三元复合材料Au NPs/g-C₃N₄/BiOBr,并通过X射线衍射、X射线光电子能谱、透射电子显微镜、紫外-可见漫反射光谱和光致发光发射光谱等技术对材料的形貌、结构进行了表征。通过在可见光下降解苯酚来评价光催化剂的活性。研究发现,Au NPs/g-C₃N₄/BiOBr显示出增强的光催化活性,对苯酚的降解能力是g-C₃N₄的3倍,是BiOBr的2.5倍。这可归因于三元复合材料的窄带隙（2.10eV）、Z型机理对光生电子-空穴对的有效分离和Au纳米颗粒的表面等离子体共振效应（SPR）。     

Determination of Amino Acids by Ru(bpy)_3~(2+) Cathodic Electrochemiluminescence with High Sensitivity

The unique cathodic electrochemiluminescence(ECL) emission of Ru(bpy)32+(bpy=2,2′-bipyridine) was observed via Nafion film at Au electrode[Au/Nafion/Ru(bpy)32+] at about 0.20 V(vs. Ag/AgCl) and applied to the determination of several amino acids without prior derivatization with high sensitivity. The cathodic electrochemilumi-nescence(ECL) exhibits the detection limits and linear ranges of several amino acids comparable to or better than those of capillary electrophoresis with conventional ECL detection method(at 1.10—1.20 V vs. Ag/AgCl) based on precolumn derivatization. The results suggest that the cathodic ECL is promising for the detection of amino acids in bioanalysis.     

Oxidation of highly unstable <4 nm diameter gold nanoparticles 850 mV negative of the bulk oxidation potential

Here we describe the oxidation of <4 nm diameter Au nanoparticles (NPs) attached to indium tin oxide-coated glass electrodes in Br(-) and Cl(-) solution. Borohydride reduction of AuCl(4)(-) in the presence of hexanethiol or trisodium citrate (15 min) led to Au NPs <4 nm in diameter. After electrochemical and ozone removal of the hexanthiolate ligands from the thiol-coated Au NPs, Au oxidation peaks appeared in the range 0-400 mV vs Ag/AgCl (1 M KCl), which is 850-450 mV negative of the bulk Au oxidation peak near 850 mV. The oxidation potential of citrate-coated Au NPs is in the 300-500 mV range and those of 4 and 12 nm diameter Au NPs in the 660-780 mV range. The large negative shift in potential agrees with theory for NPs in the 1-2 nm diameter range. The oxidation potential of Au in Cl(-) solution is positive of that in Br(-) solution, but the difference decreases dramatically as the NP size decreases, showing less dependence on the halide for smaller NPs.     

How bridging ligands and neighbouring groups tune the gold-gold bond strength

Gold-gold interactions in small polynuclear complexes are analysed using extended Hückel calculations. They are influenced by the nature of the ligand donor atoms, by the bridging ligands, but most by the formal oxidation state of the metal. Au---Au bonds are much stronger in complexes of Au(II) and Au(III), but a weak interaction between two d¹⁰ centres exists for Au(I) complexes, owing to mixing of the s and p orbitals with the d orbitals. Phosphines induce stronger metal-metal bonds when coordinated trans to the Au---Au bond in [Au(II)[(CH₂)₂PPh₂]L]₂ (Ph = phenyl), but have the opposite effect when bonded orthogonally to the metal-metal axis in Au(I) binuclear species. When two gold atoms are bridged by a single carbon atom, belonging either to mesityl (Mes = 2,4,6-Me₃C₆H₂) or CR₂, the former produces stronger Au(I)---Au(I) interactions, reflected in shorter distances. Formal oxidation states are proposed for the gold atoms in two mixed-valence clusters, [Au4(C₆F₅)₂((PPh₃)_{2CH})2(PPh3)2](ClO4)2 and [{(2,4,6-C6F3H2)Au(CH2PPh2CH2)2Au{in2}-Au(CH₂PPh₂CH₂)₂Au](ClO₄)₂. The results suggest a higher oxidation state for the outer gold atoms, in both the T-shaped tetranuclear cluster and the Au₆ linear chain.     

Silver overlayer-modified surface-enhanced Raman scattering-active gold substrates for potential applications in trace detection of biochemical species

Because Ag and Au nanoparticles (NPs) possess well-defined localized surface plasmon resonance (LSPR) they are popularly employed in the studies of surface-enhanced Raman scattering (SERS). As shown in the literature and in our previous studies, the advantage of SERS-active Ag NPs is their higher SERS enhancement over Au NPs. On the other hand, the disadvantage of SERS-active Ag NPs compared to Au NPs is their serious decay of SERS enhancement in ambient laboratory air. In this work, we develop a new strategy for preparing highly SERS-active Ag NPs deposited on a roughened Au substrate. This strategy is derived from the modification of electrochemical underpotential deposition (UPD) of metals. The coverage of Ag NPs on the roughened Au substrate can be as high as 0.95. Experimental results indicate that the SERS of Rhodamine 6G (R6G) observed on this developed substrate exhibits a higher intensity by ca. 50-fold of magnitude, as compared with that of R6G observed on the substrate without the deposition of Ag NPs. The limit of detection (LOD) for R6G measured on this substrate is markedly reduced to 2 × 10⁻¹⁵ M. Moreover, aging of SERS effect observed on this developed substrate is significantly depressed, as compared with that observed on a generally prepared SERS-active Ag substrate. These aging tests were performed in an atmosphere of 50% relative humidity (RH) and 20% (v/v) O₂ at 30 °C for 60 day. Also, the developed SERS-active substrate enables it practically applicable in the trace detection of monosodium urate (MSU)-containing solution in gouty arthritis without a further purification process.     

Using unmodified Au nanoparticles as colorimetric probes for TNT based on their competitive reactions with melamine

Gold nanoparticles(Au NPs) can serve as visualized colorimetric probes for various targets and modification-free sensing strategies are preferred.The donor–acceptor interaction between the electron-rich melamine(MA) and the electron-deficient trinitrotoluene(TNT) allows formation of a supramolecule in aqueous solution.Melamine alone makes the initially individual reddish Au NPs aggregate into gray/blue Au NP assemblies due to melamine forming multiple ligand sites toward the Au NPs.Interestingly,the preformed supramolecule of MA–TNT disenables aggregation of the Au NPs.Therefore the unmodified Au NPs provide facile colorimetric probes for TNT detection in aqueous solution.Rapid identification of TNT is established by naked eye inspection.By using spectrophotometer tools,quantification of TNT is accomplished with a linear range of 80 mmol Là1to 1.2 mmol Là1and a limit of detection(LOD) of 27 mmol Là1.In contrast to previous strategy with surface-modified Au NPs,here a modification-free sensing strategy for TNT assay has been developed with greater convenience,rapidity,and cost-effectiveness.     

Characterization and photocatalytic properties of silver and silver chloride doped TiO2 hollow nanoparticles

Using polystyrene（PSt） particles as template,PSt/TiO₂ composite particles with AgCl incorporation were prepared through hydrolysis of tetrabutyl titanate in the presence of AgNO₃ and NaCl.AgCl doped TiO₂ hollow particles were successfully prepared with the PSt/TiO₂ composite microspheres pretreated at 180℃followed by calcination.The morphology of PSt/TiO₂ particles and the crystal structures of the AgCl doped TiO₂ hollow particles were characterized.The photocatalytic activity of the doped TiO₂ hollow particles in degradation of Rhodamine B was tested under UV and visible lights and compared to that with Ag doped TiO₂ particles.The results showed that TiO₂ hollow particles,either doped with Ag or AgCl,demonstrated higher photocatalytic activity than the pure TiO₂ particles.This enhancement in photocatalytic activity was more significant with AgCl doped TiO₂ than that with Ag doped,and more distinct when the degradation was done under visible light than that under LTV light.     

pH和温度诱导双亲水嵌段共聚物聚甲基丙烯酸-b-聚N-(2-甲基丙烯酰氧乙基)吡咯烷酮水溶液的胶束化

基于可逆加成裂解链转移自由基(RAFT)聚合法开发了一系列新型双亲水嵌段共聚物——聚甲基丙烯酸-b-聚N-(2-甲基丙烯酰氧乙基)吡咯烷酮(PMAA-b-PNMP),并利用凝胶渗透色谱法(GPC)和¹H NMR对其结构进行了表征。光散射和冷冻电镜的结果表明,此类双亲水嵌段共聚物的水溶液具有pH和温度诱导胶束化的现象,而且PNMP的聚合度对胶束化的pH和温度影响都非常大。一般而言,PNMP的聚合度越大,胶束化的pH值越小,胶束化的温度则越高。pD相关的¹H NMR结果表明,PNMP与PMAA片段和水分子之间氢键的削弱以及PNMP与PMAA链之间相互作用的增强是pH诱导PMAA-b-PNMP胶束形成的主要原因,而PNMP片段与水分子之间氢键的削弱则是温度诱导PMAA-b-PNMP胶束形成的主要原因。此外,我们发现在PMAA-b-PNMP体系中制备的纳米金颗粒的大小可通过溶液pH进行可控调节。总体而言,pH值越高,金纳米颗粒的粒径越小。     

磁性印迹纳米粒子固定血红蛋白修饰磁性电极构建过氧化氢传感器

采用表面印迹技术,以磁性二氧化硅纳米粒子（Fe₃O₄@SiO₂ NPs）作为载体、血红蛋白（Hb）为模板分子、正硅酸乙酯（TEOS）为印迹聚合物单体,制备了Hb印迹Fe₃O₄@SiO₂的磁性印迹纳米粒子（MMIPs NPs）. MMIPs NPs具有磁性内核和血红蛋白印迹壳层的核壳结构,可以富集并固定Hb. 使用壳聚糖将MMIPs NPs固定于磁性电极表面,构建血红蛋白类酶生物传感器,研究了Hb对过氧化氢（H₂O₂）的催化活性. MMIPS NPS相比于磁性非印迹纳米粒子（MNIPS NPS）,催化电流增加了14.3%. 采用磁性电极,MMIPS NPS、Hb和O₂的顺磁性使得该类酶生物传感器对H₂O₂的催化电流增加了60.0%. 血红蛋白类酶生物传感器电流响应与H₂O₂浓度在25 ~ 200 μmol·L^-1间呈线性关系,检出限为3 μmol·L^-1（S/N=3）,表明该类酶传感器对H₂O₂具有良好的催化性能.     

A Comparative Toxicity Study of TiO2 Nanoparticles in Suspension and Adherent Culture Under the Dark Condition

The present study focused on the different acute toxicity of TiO₂ nanoparticles(TiO₂ NPs) towards the bacteria in suspension culture and adherent culture under the dark conditions. The study investigated the bacteria toxicity with TiO₂ NPs at different concentrations(1—2000 mg/L), sizes(10 nm, 35 nm) and specific surface areas in unit volume solution(0—224 m²/L) characterized by the cell viability, extracellular polymeric substances(EPS) release and biofilm formation. The bacteria in adherent culture was found to be more resistant against the toxicity of TiO₂ NPs compared to that in suspension culture. An NP dose and surface area dependent(rather than the size) bacterial viability was observed in suspension culture, specifically the surface area positively correlated with the toxicity of TiO₂ NPs. The size of TiO₂ NPs, however, played a more critical role in toxicity of TiO₂ NPs in adherent culture. Therefore, the surface area dependent toxicity of TiO₂ NPs is a comprehensive parameter describing the dose and size dependent toxicity of TiO₂ NPs. The electron microscopic(SEM, TEM, EDX) observations suggested the EPS release and biofilm formation, during aggregation of TiO₂ NPs on the bacteria after 12 h cultivation in adherent culture under the dark condition. A possible toxic mechanism could be that “effective surface areas” that directly contact with the bacterial membrane greatly contributed to the toxicity of TiO₂ NPs in both suspension culture and adherent culture. Therefore, as for the possible resistance mechanism, EPS secretion and subsequent biofilm formation may protect the bacteria against the toxicity of TiO₂ NPs.     

Fabrication of high performance thin films from metal fluorocomplex aqueous solution by the liquid phase deposition

The hetro-structured oxide thin films from metal fluorocomplex solution have been prepared by the liquid phase deposition (LPD) method. The Pt/Nb₂O₅ and Au/Nb₂O₅ composite films can be prepared from a mixed solution of niobium source, H₃BO₃, Pt(NH₃)₄Cl₂ and HAuCl₄ aqueous solutions under the ambient temperature and atmosphere. In the case of Au/SiO₂ composite film, (NH₄)₂SiF₆ solution is used as a mother solution. The Pt and Au ionic species are deposited in Nb₂O₅ and SiO₂ matrices. They are reduced to their metallic state after treatment above 200 °C. The size of dispersed particles can be controlled by heat treatment temperature. It is also clear that, gold nanoparticles are also found to interact with SiO₂, although the interaction is smaller than that with Nb₂O₅ showing the size of Au nanoparticles remain smaller in Nb₂O₅ that in SiO₂.     

通过g-C3N4担载MNi12 (Fe,Co, Cu,Zn)纳米团簇调节甲烷化

As a unique two-dimensional material, graphitic carbon nitride (g-C₃N₄) has received significant attention for its particular electronic structure and chemical performance. Its instinctive defect can provide a stable anchoring site for metals, potentially improving the surface reactivity. Ni-based catalysts are economical but their activity for CO₂ methanation is lower than that of noble metal catalysts. Ni nanoparticles (NPs) supported on a substrate can further enhance the stability and activity of catalysts. Based on the principles of strong metal-support interaction (SMSI) and the synergistic effect on an alloy, MNi₁₂/g-C₃N₄ composites as novel catalysts are expected to improve stability and catalytic performance of Ni-based catalysts. The configurations are established with core-shell structures of MNi₁₂ (M = Fe, Co, Cu, Zn) nanoparticles (NPs) supported on g-C₃N₄ in this work. In the CO₂ methanation reaction, the reactivity of CO on slab (E_CO) is a critical factor, which is relative to the catalytic activity. Thus, the catalytic reactivity of these complexes via CO adsorption were explored using density functional theory (DFT). The values of cohesive energy (E_coh) for MNi₁₂ NPs range from -39.90 eV to -34.82 eV, suggesting that the formation of these NPs is favored as per thermodynamics, and E_coh and partial density of state (PDOS) reveal that the central M atom with the less filled d-shell interacts more strongly with surface Ni atoms. Therefore, ZnNi₁₂ is the most unstable structure among all the studied alloy, and the synergistic effect is also the weakest among them. When MNi₁₂ NPs are supported on the g-C₃N₄ substrate, the binding energies (E_b) vary from -9.40 eV to -8.39 eV, indicating that g-C₃N₄ is indeed a good material for stabilizing these NPs. The PDOS analysis of pure g-C₃N₄ suggests the sp² dangling bonds of N atoms in g-C₃N₄ can stabilize these transition metal NPs. Furthermore, the results of CO adsorbed on MNi₁₂ NPs and MNi₁₂/g-C₃N₄ composites show that E_CO and d_CO reduced with the introduction of g-C₃N₄. According to the results of the analysis of the Hirshfeld charges and electrostatic potential (ESP), the reason is that CO obtains less electrons from MNi₁₂ NPs after deposition on the g-C₃N₄ substrate, which lowers the reactivity of CO on catalysts. Additionally, the deformation charge density is analyzed to investigate the interaction between the NPs and g-C₃N₄. With the introduction of g-C₃N₄, charge redistribution indicates the strong metal-support interaction, which further reduces the CO adsorption energy. In summary, MNi₁₂ supported on g-C₃N₄ exhibit not only high stability but also tunable reactivity in CO₂ methanation. These changes are beneficial for CO₂ methanation reaction.     

Pt/Au/Fe3O4的制备及其电化学性能

以制得的纳米Fe₃O₄颗粒作为载体,用还原法将还原出的Au与Pt分别负载到Fe₃O₄颗粒表面,制得纳米Pt/Au/Fe₃O₄复合材料。对Pt/Au/Fe₃O₄进行紫外可见光吸收光谱、透射电子显微镜、X射线衍射及光电子能谱等物理表征,结果表明,Au与Pt均匀地沉积到了Fe₃O₄纳米颗粒表面。对纳米Pt/Au/Fe₃O₄复合材料进行循环伏安扫描,当H₂PtCl₆的加入量达到8 mL时,Pt/Au/Fe₃O₄催化性能最佳;正扫电流峰i_p与扫描速率的平方根v^1/2线性相关,Pt/Au/Fe₃O₄催化氧化甲醇的过程受扩散控制;对催化剂进行201次循环伏安扫描,催化剂仍然能保持较好的催化性能且稳定性良好。因此,所合成催化剂Pt/Au/Fe₃O₄是一种具有良好化学稳定性的阳极催化剂材料。     

Organometallic complexes for nonlinear optics: Part 31. Cubic hyperpolarizabilities of ferrocenyl-linked gold and ruthenium complexes

The complexes [Fe{η-C₅H₄---(E)---CH=CH---4-C₆H₄CCX}₂] [X=SiMe₃ (1), H (2), Au(PCy₃) (3), Au(PPh₃) (4), Au(PMe₃) (5), RuCl(dppm)₂ (7), RuCl(dppe)₂ (8)] and [Fe{η-C₅H₄---(E)---CH=CH---4-C₆H₄CH=CRuCl(dppm)₂}₂](PF₆)₂ (6) have been prepared and the identities of 1 and 7 confirmed by single-crystal X-ray structural studies. Complexes 1–8 exhibit reversible oxidation waves in their cyclic voltammograms attributed to the Fe^II/III couple of the ferrocenyl groups, 6–8 also showing reversible (7, 8) or non-reversible (6) processes attributed to Ru-centered oxidation. Cubic nonlinearities at 800 nm by the Z-scan method are low for 1–5; in contrast, complexes 6 and 7 exhibit large negative γ_real and large γ_imag values. A factor of 4 difference in γ and two-photon absorption cross-section σ₂ values for 6 and 7 suggest that they have potential as protically switchable NLO materials.     

Aurophilic attraction: the additivity and the combination with hydrogen bonds

The coexistence of gold–gold contacts and hydrogen bonding is studied in the model system [H₂P(OH)AuCl]₂ and [H₂P(OH)AuPH₂(O)]₂. The two interactions are found to be comparable. The possible non-additivity of the aurophilic, Au(I)–Au(I) interaction is studied at MP2 level for the pentagonal [Au(SH)₂(AuSH)₅)]⁻ and hexagonal [Au(SH)₂(AuSH)₆]⁻ clusters. The possibilities of ‘mechanical cooperativity’ between different aurophilic attractions and of Au…S attractions are also considered.     

New organogold(I) complexes: Synthesis, structure, and dynamic behavior of the polynuclear organogold diphenylmethane and diphenylethane derivatives

Two organogold derivatives of diphenylmethane and diphenylethane, Ph₃PAu(o-C₆H₄)CH₂(C₆H₄-o)AuPPh₃ (1) and Ph₃PAu(o-C₆H₄)(CH₂)₂(C₆H₄-o)AuPPh₃ (2), have been synthesized by the reaction of ClAuPPh₃ with Li(o-C₆H₄)CH₂(C₆H₄-o)Li and Li(o-C₆H₄)(CH₂)₂(C₆H₄-o)Li respectively. The interaction of 1 with dppe results in the replacement of the two PPh₃ groups to give a macrocyclic compound (3) that includes an Au Au bond. Compounds 1 and 2 react with one or two equivalents of [Ph₃PAu]BF₄ to form new types of cationic complex [CH₂(C₆H₄-o)₂(AuPPh₃)₃]BF₄ (4), [CH₂(C₆H₄-o)₂(AuPPh₃)₄](BF₄)₂ (5), and [(CH₂)₂(C₆H₄-o)₂(AuPPh₃)₄](BF₄)₂ (6). Complexes 1–6 have been characterized by X-ray diffraction studies, FAB MS, and IR as well as by ¹H and ³¹P NMR spectroscopy. A complicated system of Au H-C agostic interactions, involving the bridging alkyl groups (—CH₂— and CH₂-CH₂—) of diphenylmethane and diphenylethane ligands, has been found to occur in complexes 1–3 and 6.