Partitioning of unsaturated hydrophilic monomer in microemulsion media monitored by pyrene fluorescence method

The extent of intra‐ and interchain associations of (un)charged water‐soluble monomers in the homogeneous and micellar solutions was studied with steady‐state fluorescence spectroscopy. Fluorescence spectroscopic experiments were performed on uncharged (acryl amide) and charged hydrophilic monomers [zwitterionic 3‐dimethyl(methacryloyloxyethyl)ammonium propane sulfonate (DMAPS), etc.] with pyrene as a probe. In both the homogeneous and micellar solutions, linear Stern–Volmer plots were obtained that implied that the quenching process can be considered as totally dynamic. The Stern–Volmer constant (K_SV) for DMAPS decreased with an increasing dielectric constant of solvent and the concentration of simple electrolyte. An abrupt decrease in K_SV was observed in the presence of a small amount of anionic emulsifier [below the critical micelle concentration (cmc)]. The dependence of K_SV on pH for DMAPS was described by a curve with a maximum at about pH = 7. This was interpreted in terms of segregation of DMAPS and the variation of a optimal microenvironment for the probe and quencher with pH. The quenching rate in the micellar solutions strongly increased above the cmc but was lower than that in the homogeneous solutions. In the micellar solutions (above the cmc), the microenvironment for an interaction between the probe and quencher was suggested to be the whole microdroplet. The dependence of K_SV on pH for DMAPS is described by a curve with a maximum at about pH = 9.3. The synergistic effect arises from the segregation of charged quencher molecules within the microdroplets. The complex (or strong interaction) between quencher and additive(s) is supposed to increase the dynamic nature of microdroplets that provides an optimal microenvironment for probe and quencher. A good coemulsifier, however, removes quencher from the interface and creates a barrier for entering monomer (quencher) into the core of micelles; therefore, quenching is depressed. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 571–581, 2003     

Experimental and Theoretical Evidence of the Existence of Gold(I)⋅⋅⋅Mercury(II) Interactions in Solution through Fluorescence‐Quenching Measurements

Heteronuclear complexes {[Hg(R)₂][Au(R′)(PMe₃)]₂}_n (R=R′=C₆Cl₂F₃ ( 3 ); R=R′=C₆F₅ ( 4 ); R=C₆Cl₂F₃, R′=C₆F₅ ( 5 ); R=C₆F₅, R′=C₆Cl₂F₃ ( 6 )) were prepared by the treatment of the corresponding organomercury compounds, [Hg(C₆X₅)₂], with two equivalents of [Au(C₆X₅)(PMe₃)]. Their crystal structures, as determined by using X‐ray diffraction methods, display Au???Hg interactions. Although only compound 4 and 5 show luminescence in the solid state, all of these compounds quench the fluorescence of naphthalene in solution. Solution studies of these derivatives suggest a cooperative effect of the gold(I) center in switching on the quenching capabilities of the [Hg(C₆X₅)₂] synthon with naphthalene. Theoretical studies confirmed the quenching ability of the organomercury species in the presence of gold.     

Synthesis,characterization, and biological activities of a Cu(II) complex with the non-steroidal antiinflammatory drug flufenamic acid

[Cu^II(L)₂.C₁₂H₁₀N₂] with flufenamic acid (HL=C₁₄H₁₀F₃NO₂) and phenanthroline (C₁₂H₁₀N₂O) was synthesized and characterized by C, H and N elemental analysis, single-crystal X-ray diffraction and, IR spectra. The urease inhibitory and antibacterial activities of the complex were tested. The complex showed strong inhibitory activity against jack bean urease with an IC₅₀ value of 0.265 μM. Four bacteria, Bacillus subtilis, Escherichia coli, Staphylococcus aureus, and proteusbacillus vulgaris, were used in the antibacterial test. The complex showed strong inhibitory activity against the species with IC₅₀ values of 2.016, 35.037, 10.680, and 3.820 μM. The interactions of the complex with human serum albumin (HSA) were studied through fluorescence spectroscopy. By analyzing the experimental data, we concluded that the fluorescence quenching mechanism of the complex with serum albumin was static quenching. The binding mode of the complex with DNA through UV spectroscopy was electrostatic binding or groove.     

聚乙二醇增敏亚甲蓝-四苯硼化钠离子缔合物荧光探针荧光猝灭法测定痕量蛋白质

在KH2PO4- Na2HPO4缓冲溶液中，离子缔合物[MB]+·[B(C6H5)4]–可发射强而稳定的荧光，牛血清蛋白（BSA）能使[MB]+·[B(C6H5)4]–的荧光信号显著猝灭，聚乙二醇(PEG)对荧光信号猝灭的有强的增敏作用，加PEG比不加PEG时，ΔF（= F0－F，其中，F0与F分别为试剂空白和试液的荧光强度）值提高了9.1倍，且ΔF与BSA含量具有良好的线性关系，据此建立了新型荧光探针荧光猝灭法测定痕量蛋白质的新方法。本方法的线性范围为0.11 ~ 88.0 ag/mL，检出限：22.0 ag /mL BSA，灵敏度很高，并成功用于人血清样品中蛋白含量的测定。同时探讨了新方法的反应机理。在相同条件下，新方法可分别测定BSA、人血清白蛋白(human serum albumin，HAS)、卵蛋白(ovalbumin，OVA )、γ-球蛋白(γ-globulin，γ-G)及血清、脑脊液样品中蛋白质总量。     

Basicity of bisperhalophenyl aurates toward closed-shell metal ions: metallophilicity and additional interactions

The interaction of bisperhalophenyl aurates [AuR₂]^? (R?=?C₆F₅, C₆F₃Cl₂, and C₆Cl₅) with the closed-shell Ag⁺, Cu⁺, and Tl⁺ ions has been studied theoretically and compared with the experimentally known X-ray diffraction crystal structures. Initially, the aurates have been fully optimized at MP2 level of theory in a D _2h symmetry. The analysis of the basicity of the three aurates [AuR₂]^? (R?=?C₆F₅, C₆F₃Cl₂ and C₆Cl₅) against Ag⁺ ions in a C _2v symmetry has been calculated in point-by-point bsse-corrected interaction energy analysis at HF and MP2 levels of theory. Taking into account the experimental observation of additional interactions between the heterometals and C _ipso atoms at the perhalophenyl rings or halogen atoms at the ortho position of the perhalophenyl rings, dinuclear models of the type [AuR₂]^?···Ag⁺ (R?=?C₆Cl₅, and C₆F₅); [AuR₂]^?···Cu⁺ (R?=?C₆F₅, and C₆Cl₅) and [AuR₂]^?···Tl⁺ (R?=?C₆F₅, and C₆Cl₅) with a C _2v , C ₂ , and C _s symmetries have been optimized at DFT-B3LYP level. The interaction energies have been computed through bsse-corrected single point HF and MP2 calculations. The energy stabilization provided and the heterometal preference have been analyzed and compared with the experimental results.     

Supramolecular inclusion of a pillared double-layered host by an anion-directed second-sphere coordination

In this paper, we have illustrated the utilisation of a second-sphere coordination approach to construct supramolecular inclusion solids with varieties of guest molecules. A flexible molecule N,N,N′,N′-tetra-p-methylbenzyl-ethylenediamine (L1) bearing doubly protonated H-bond donors was designed, capable of forming N–H…Cl hydrogen bonds with a crystallographically unique chloride anion, to construct an anion-directed ligand. The pillared double-layered host framework was constructed by an anion-directed ligand and primary coordination sphere [CoCl₄]^2 ?  through weak C–H…Cl hydrogen-bonding interactions. A variety of guest molecules, such as p-anisaldehyde, 1,4-dimethoxy-2,5-bis(methoxymethyl)benzene, can be included, leading to the formation of novel supramolecular inclusion solids: [L1]·4[H]⁺·[CoCl₄]^2 ? ·2Cl^? ·1.5[C₈H₈O₂]·0.25[CH₃OH] (1) and [L1]·4[H]⁺·[CoCl₄]^2 ? ·2Cl^? ·1.5[C₁₂H₂₀O₄]·0.5[CH₃OH] (2).

We have presented herein the utilisation of a second-sphere coordination approach to construct supramolecular inclusion solids with a variety of guest molecules. A novel type of a pillared double-layered host framework was constructed by a second-sphere coordination between the anion-directed ligand (L1 = N,N,N′,N′-tetra-p-methylbenzyl-ethylenediamine) and [CoCl₄]^2 ?  through weak C–H…Cl hydrogen-bonding interaction, and a variety of guest molecules, such as p-anisaldehyde, 1,4-dimethoxy-2,5-bis(methoxymethyl)benzene, can be included, leading to the formation of supramolecular inclusion solids: [L1]·4[H]⁺·[CoCl₄]^2 ? ·2Cl^? ·1.5[C₈H₈O₂]·0.25[CH₃OH] (1) and [L1]·4[H]⁺·[CoCl₄]^2 ? ·2Cl^? ·1.5[C₁₂H₂₀O₄]·0.5[CH₃OH] (2)

     

Structural Dynamics of Isomorphic Substitution in N,N′-Diallylbenzimidazolium Copper Halide π-Complexes [C7H5N2(C3H5)2]+[Cu2Cl3?xBrx]? (x=0, 1.60, 2.33, 3)

Two new -complexes of copper(I) halides with the 1,3-diallylbenzimidazolium cation, [C₇H₅N₂(C₃H₅)₂]⁺[Cu₂Cl_1.40Br_1.60]^– and [C₇H₅N₂(C₃H₅)₂]⁺[Cu₂Br₃]^–, have been synthesized and structurally defined (space group P2 ₁/c for both; a = 22.094(6), b = 9.272(8), c = 9.22(1) , = 118.26(4)° and a = 22.267(5), b = 9.311(3), c = 9.263(2) , = 117.51(2)°). The mutual effects of chlorine–bromine substitution and the efficiency of -interactions are discussed based on XRD data for these two compounds and for the compounds [C₇H₅N₂(C₃H₅)₂]⁺[Cu₂Cl₃]^– and [C₇H₅N₂(C₃H₅)₂]⁺[Cu₂Cl_0.67Br_2.33]^– studied previously.     

Reactions of 3-(Polyfluoroalkyl)propane-1,2,3-trione-2-oximes with Diaminoarenes

Novel quinoxaline derivatives have been synthesized via the reaction of 3-trifhioromethyl-1,2,3-propanetrione-2-oximes with 1,2-diaminobenzene or 2,3-diaminonaphthalene: 2-trifluoromethyl-3-aroylquinoxaline and 2-trifluoromethyl-3-aroylbenzo[g]quinoxaline. Under similar conditions, 3-R^F-1,2,3-propanetrione-2-oximes [R^F = C₃F₇, H(CF₂)₄, C₄F₉, and C₆F₁₃] with the same diaminoarenes have given a mixture of the condensation and fragmentation products in different ratios. The structure of (4-methylphenyl)[3-(tri-fluoromethyl)benzo[g]quinoxalin-2-yl]methanone has been elucidated by means of X-ray diffraction analysis.

     

Exploring Reversible Quenching of Fluorescence from a Pyrazolo[3,4‐b]quinoline Derivative by Protonation

Pyrazolo[3,4‐b]quinoline derivatives are reported to be highly efficient organic fluorescent materials suitable for applications in light‐emitting devices. Although their fluorescence remains stable in organic solvents or in aqueous solution even in the presence of H₂O, halide salts (LiCl), alkali (NaOH) and weak acid (acetic acid), it suffers an efficient quenching process in the presence of protic acid (HCl) in aqueous or ethanolic solution. This quenching process is accompanied by a change in the UV spectrum, but it is reversible and can be fully recovered. Both steady‐state and transient fluorescence spectra of 1‐phenyl‐3,4‐dimethyl‐1H‐pyrazolo‐[3,4‐b]quinoline (PAQ5) during quenching are measured and analyzed. It is found that a combined dynamic and static quenching mechanism is responsible for the quenching processes. The ground‐state proton‐transfer complex [PAQ5 ??? H⁺] is responsible for static quenching. It changes linearly with proton concentration [H⁺] with a bimolecular association constant K_S=1.95 M ^?1 controlled by the equilibrium dissociation of HCl in ethanol. A dynamic quenching constant K_D=22.4 M ^?1 is obtained by fitting to the Stern–Volmer equation, with a bimolecular dynamic quenching rate constant k_d=1.03×10⁹ s^?1 M ^?1 under ambient conditions. A change in electron distribution is simulated and explains the experiment results.     

Electrochemiluminescence Quenching by Halide Ions at Bipolar Electrodes

Quenching of Ru(bpy)₃²⁺ electrochemiluminescence (ECL) by Cl^?, Br^?, and I^? ions was studied as a function of halide concentration in a bipolar electrochemical cell. All of the halides investigated showed similar qualitative behavior: above a critical concentration, ECL intensity was found to decrease linearly as the halide ion concentration was increased, due to dynamic quenching of Ru(bpy)₃²⁺ ECL. Stern‐Volmer slopes (K_SV) of 0.111±0.003, 4.2±0.3, and 6.2±0.3 mM^?1 were measured for Cl^?, Br^? and I^?, respectively. The magnitude of K_SV correlates with halide ion oxidation potential, consistent with an electron transfer quenching mechanism. Using the bipolar platform described herein, aqueous, halide‐containing solutions could be quantified rapidly using the sequential standard addition method. The lower detection limit is determined by a complex mechanism involving the competitive electrooxidation of halide ions and the ECL co‐reactants, as well as the passivation of the surface of the bipolar electrode, and was found to be 0.20±0.01, 0.08±0.01 and 10±1 mM, respectively, for I^?, Br^?, and Cl^?. The performance of the bipolar ECL quenching assay is comparable to previously published fluorescence quenching methods for the determination of halide ions, while being much simpler and less expensive to implement.     

The Reactivity of Potassium Polyfluoroaryl‐, Polyfluoroalkenyl‐, and Perfluoroalkyltrifluoroborates and their Hydrocarbon Analogues towards Acids of Different Strength: A Systematic Study of the Hydrodeboration

The hydrodeboration of the (fluoroorgano)trifluoroborates K [R_FBF₃] [R_F = C₆F₅, XCF=CF (X = F, cis‐ and trans‐Cl, C₃F₇O, cis‐C₂F₅, trans‐C₄F₉, ‐C₄H₉) and C₆F₁₃] and of the organotrifluoroborates K [RBF₃] (R = C₆H₅, cis‐ and trans‐C₄H₉CH=CH, C₄H₉ and C₈H₁₇) with CH₃CO₂H (100 %), CF₃CO₂H (100 %), aqueous HF and anhydrous HF was investigated. In the alkenyltrifluoroborates K [R'CF=CFBF₃] the formal replacement of BF₃ by a proton occurred stereospecifically under retention of the configuration. The ¹⁹F NMR spectra of K [R_FBF₃] in acids indicate strong interactions of the BF₃ group with protons or acid molecules.     

Study of a fluorescence quenching mechanism of enoxacin and its determination in human serum and urine samples

The maximum emission wavelength of dopamine is 317 nm with excitation at 290 nm. The relative fluorescence intensity of dopamine decreased in the presence of enoxacin, which showed that fluorescence quenching occurred. The Stern-Volmer (S-V) plot showed a nonlinear relationship between the relative fluorescence intensity of dopamine and the concentration of enoxain. The quenching mechanism was studied and the results suggested that both dynamic and static quenching processes were responsible for the observed positive deviation in the S-V plot. When the S-V plot was modified by logarithm, the linear relationship was obtained between logF ₀/F and C in the range of 0.10 to 13.0 μg/mL (where F ₀ is the relative fluorescence intensity of dopamine, F is the relative fluorescence intensity of dopamine in the presence of enoxacin, and C is the concentration of enoxacin). The fluorescence quenching method for the determination of enoxacin was developed. The linear regression equation of the calibration graph of enoxacin was C = 13.70 (logF ₀/F) − 0.5836, with the correlation coefficient 0.9984. The detection limit was 2.0 ng/mL and the relative standard deviation was 2.52%. The effects of pH, the stability of dopamine in the presence of enoxacin, and foreign ions on the determination of enoxacin have been examined. The recovery of enoxacin was from 94.9 to 103.0% in a human serum sample and from 94.9 to 108.0% in a urine sample. The method is simple, rapid, and can be used for the determination of enoxacin in human serum and urine samples with satisfactory results. The text was submitted by the authors in English.     

Fluorescence and DNA-binding spectral studies of neodymium(III) complex containing 2,2′-bipyridine, [Nd(bpy)2Cl3·OH2]

The interaction of [Nd(bpy)₂Cl₃·OH₂], where bipy is 2,2′-bipyridine, with DNA has been studied by absorption, emission, and viscosity measurements. [Nd(bpy)₂Cl₃·OH₂] showed absorption decreasing in charge transfer band with increasing of DNA. The binding constant, K_b has been determined by absorption measurement and found to be (1.5 ± 0.1) × 10⁵ M^?1. The fluorescent of [Nd(bpy)₂Cl₃·OH₂] has been investigated in detail. The interaction was also studied by fluorescence quenching technique. The results of fluorescence titration revealed that DNA had the strong ability to quenching the intrinsic fluorescence of Nd(III) complex at 327 nm. The binding site number n, apparent binding constant K_b and the Stern–Volmer quenching constant K_SV have been determined. Thermodynamic parameters have been calculated according to relevant fluorescent data and Van’t Hoff equation. Characterization of bonding mode has been studied. The results suggested that the major interaction mode between [Nd(bpy)₂Cl₃·OH₂] and DNA was groove binding.     

Polyfluorophore Labels on DNA: Dramatic Sequence Dependence of Quenching

We describe studies carried out in the DNA context to test how a common fluorescence quencher, dabcyl, interacts with oligodeoxynucleoside fluorophores (ODFs)—a system of stacked, electronically interacting fluorophores built on a DNA scaffold. We tested twenty different tetrameric ODF sequences containing varied combinations and orderings of pyrene (Y), benzopyrene (B), perylene (E), dimethylaminostilbene (D), and spacer (S) monomers conjugated to the 3′ end of a DNA oligomer. Hybridization of this probe sequence to a dabcyl‐labeled complementary strand resulted in strong quenching of fluorescence in 85 % of the twenty ODF sequences. The high efficiency of quenching was also established by their large Stern–Volmer constants (K_SV) of between 2.1×10⁴ and 4.3×10⁵ M ^?1, measured with a free dabcyl quencher. Interestingly, quenching of ODFs displayed strong sequence dependence. This was particularly evident in anagrams of ODF sequences; for example, the sequence BYDS had a K_SV that was approximately two orders of magnitude greater than that of BSDY, which has the same dye composition. Other anagrams, for example EDSY and ESYD, also displayed different responses upon quenching by dabcyl. Analysis of spectra showed that apparent excimer and exciplex emission bands were quenched with much greater efficiency compared to monomer emission bands by at least an order of magnitude. This suggests an important role played by delocalized excited states of the π stack of fluorophores in the amplified quenching of fluorescence.     

Synthesen,Eigenschaften und Kristallstrukturen der Cluster‐Salze Bi6[PtBi6Cl12] und Bi2/3[PtBi6Cl12]

Syntheses, Properties and Crystal Structures of the Cluster Salts Bi₆[PtBi₆Cl₁₂] and Bi_2/3[PtBi₆Cl₁₂] Melting reactions of Bi with Pt and BiCl₃ yield shiny black, air insensitive crystals of the subchlorides Bi₆[PtBi₆Cl₁₂] and Bi_2/3[PtBi₆Cl₁₂]. Despite the substantial difference in the bismuth content the two compounds have almost the same pseudo‐cubic unit cell and follow the structural principle of a CsCl type cluster salt. Bi₆[PtBi₆Cl₁₂] consists of cuboctahedral [PtBi₆Cl₁₂]^2? clusters and Bi₆²⁺ polycations (a = 9.052(2) Å, α = 89.88(2)°, space group P 1, multiple twins). In the electron precise cluster anion, the Pt atom (18 electron count) centers an octahedron of Bi atoms whose edges are bridged by chlorine atoms. The Bi₆²⁺ cation, a nido cluster with 16 skeletal electrons, has the shape of a distorted octahedron with an opened edge. In Bi_2/3[PtBi₆Cl₁₂] the anion charge is compensated by weakly coordinating Bi³⁺ cations which are distributed statistically over two crystallographic positions (a = 9.048(2) Å, α = 90.44(3)°, space group ). Bi₆[PtBi₆Cl₁₂] is a semiconductor with a band gap of about 0.1 eV. The compound is diamagnetic at room temperature though a small paramagnetic contribution appears towards lower temperature.     

Reactions of (Nonafluorocyclohexen-1-yl)xenon(II) Hexafluoroarsenate with Halide Anions

The products of the reaction between the electrophilic alkenylxenonium cation [1-Xe⁺–C₆F₉] and the halide anions I^?, Br^?, Cl^? and F^? depend on the hardness of the halide anion. With the soft halides I^? and Br^? Xe(II) is formally displaced by halogen as well in basic MeCN as in superacidic (AHF¹), whereas with hard fluoride and chloride no reaction takes place in AHF. In MeCN F^? initiates the formation of alkenyl radicals, which abstract hydrogen from the solvent, whereas Cl^? exhibits borderline character: RH and RCl formation. Possible reaction paths are discussed. The reactivity of the arylxenonium cation [C₆F₅Xe]⁺ in AHF toward halide ions is reported and the relative electrophilicity of the cations [C₆F₅Xe]⁺ and [1-Xe⁺–C₆F₉] is determined by the competitive reaction with Cl^?. In addition the synthesis of cyclohexene 1-CF₃–C₆F₉ from C₆F₅CF₃ and XeF₂ is performed and its electrophilicity is compared with that of the aromatic compound C₆F₅CF₃.     

通过阳离子的部分氯化和氟化提高离子液体的憎水性

报道了一类咪唑环阳离子上同时含有氯和氟元素的新型离子液体,即 和 。这类离子液体是将其前驱体甲基丁基咪唑氯盐或甲基丁基咪唑六氟磷酸盐经过氯化取代和氟化取代反应来制备的。采用氢核磁共振谱（1H-NMR）确定了氯化反应过程中氯取代氢的位置,结果表明,氯主要取代咪唑环上的氢以及部分丁基侧链上甲基基团中的氢。考察了这类离子液体的水溶性,热稳定性以及黏度。结果表明,离子液体经氯化和氟化处理可以显著提高其憎水性。     

Preparation and properties of stable mono-, tris-, tetrakis- or hexakis(pentahalophenyl)thalliate(III) complexes

Reaction of TlR₂X, TlX₃ and [TlX₄^? with RLi ( R = C₆F₅ or C₆Cl₅) leads to derivatives containing anions of the types [TlR₄]^?, [TlR₂R′₂]^? or [TlR₆]^3?. Reactions of TlCl₃ with [TlR₄]^? lead to [(μ-Cl)(TlR₂Cl)₂]^? (R = C₆F₅) or [TlRCl₃]^? (R = C₆Cl₅) while addition of X^? (X = Br^? or SCN^?) to Tl(C₆Cl₅)₃ gives [Tl- (C₆Cl₅)₃X]^?. All the novel anions were isolated as salts of bulky cations (Me₄N, Bu₄N, PPN or Ph₃BzP).     

One- and Two-Electron Transfer Oxidation of 1,4-Disilabenzene with Formation of Stable Radical Cations and Dications

Electron-transferable oxidants such as B(C₆F₅)₃/nBuLi, B(C₆F₅)₃/LiB(C₆F₅)₄, B(C₆F₅)₃/LiHBEt₃, Al(C₆F₅)₃/(o-RC₆H₄)AlH₂ (R=N(CMe₂CH₂)₂CH₂), B(C₆F₅)₃/AlEt₃, Al(C₆F₅)₃, Al(C₆F₅)₃/nBuLi, Al(C₆F₅)₃/AlMe₃, (CuC₆F₅)₄, and Ag₂SO₄, respectively were employed for reactions with (L)₂Si₂C₄(SiMe₃)₂(C₂SiMe₃)₂ (L=PhC(NtBu)₂, 1 ). The stable radical cation [ 1 ]^+. was formed and paired with the anions [nBuB(C₆F₅)₃]⁻ (in 2 ), [B(C₆F₅)₄]⁻ (in 3 ), [HB(C₆F₅)₃]⁻ (in 4 ), [EtB(C₆F₅)₃]⁻ (in 5 ), {[(C₆F₅)₃Al]₂(μ-F)]⁻ (in 6 ), [nBuAl(C₆F₅)₃]⁻ (in 7 ), and [Cu(C₆F₅)₂]⁻ (in 8 ), respectively. The stable dication [ 1 ]²⁺ was also generated with the anions [EtB(C₆F₅)₃]⁻ ( 9 ) and [MeAl(C₆F₅)₃]⁻ ( 10 ), respectively. In addition, the neutral compound [(L)₂Si₂C₄(SiMe₃)₂(C₂SiMe₃)₂][μ-O₂S(O)₂] ( 11 ) was obtained. Compounds 2 – 11 are characterized by UV-vis absorption spectroscopy, X-ray crystallography, and elemental analysis. Compounds 2 – 8 are analyzed by EPR spectroscopy and compounds 9 – 11 by NMR spectroscopy. The structure features are discussed on the central Si₂C₄-rings of 1 , [ 1 ]^+., [ 1 ]²⁺, and 11 , respectively.     

A Systematic Investigation of Coinage Metal Carbonyl Complexes Stabilized by Fluorinated Alkoxy Aluminates

The reaction of Cu^I, Ag^I, and Au^I salts with carbon monoxide in the presence of weakly coordinating anions led to known and structurally unknown non‐classical coinage metal carbonyl complexes [M(CO)_n][A] (A=fluorinated alkoxy aluminates). The coinage metal carbonyl complexes [Cu(CO)_n(CH₂Cl₂)_m]⁺[A]^? (n=1, 3; m=4?n), [Au₂(CO)₂Cl]⁺[A]^?, [(OC)_nM(A)] (M=Cu: n=2; Ag: n=1, 2) as well as [(OC)₃Cu???ClAl(OR^F)₃] and [(OC)Au???ClAl(OR^F)₃] were analyzed with X‐ray diffraction and partially IR and Raman spectroscopy. In addition to these structures, crystallographic and spectroscopic evidence for the existence of the tetracarbonyl complex [Cu(CO)₄]⁺[Al(OR^F)₄]^? (R^F=C(CF₃)₃) is presented; its formation was analyzed with the help of theoretical investigations and Born–Fajans–Haber cycles. We discuss the limits of structure determinations by routine X‐ray diffraction methods with respect to the C? O bond lengths and apply the experimental CO stretching frequencies for the prediction of bond lengths within the carbonyl ligand based on a correlation with calculated data. Moreover, we provide a simple explanation for the reported, partly confusing and scattered CO stretching frequencies of [Cu^I(CO)_n] units.