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1.
Equilibria between aluminium(III), pyrocatechol (1,2-dihydroxybenzene, H 2L) and OH − were studied in 0.6 M Na(Cl) medium at 25°C. The measurements were performed as emf titrations (glass electrode) within the limits 1.5 ≤ − log[H +] ≤ 9; 0.0005 ≤ B ≤ 0.015 M; 0.006 ≤ C ≤ 0.03 M and 2 ≤ C/B ≤ 30 ( B and C stand for the total concentrations of aluminium(III) and pyrocatechol respectively). All data can be explained with a main series of complexes: A1L +, log β −2,1,1 = − 6.337 ± 0.005; A1L 2−, log β −4,1,2 = −15.44 ± 0.017 and A1L 33−, log β −6,1,3 = − 28.62 ± 0.024 together with two minor species: Al(OH)L 22−, log β −5,1,2 = − 23.45 ± 0.079 and Al 3(OH) 3L 3, log β −9,3,3 = − 29.91 ± 0.066. Of the two, the latter probably is a type of average composition complex principally occurring at low C/B quotients. The first acidity constant for pyrocatechol as determined in separate experiments is log β −1,0,1 = − 9.198 ± 0.001. The standard deviations given are 3σ(log β p,q,r). Data were analyzed with the least squares computer program LETAGROPVRID. In a model calculation using kaolinite as solid phase, we compared the complexation ability of this system with that of the system Al 3+-OH −-salicylic acid, reported earlier in this series. 相似文献
2.
The highly neutralized ethylenediaminetetraacetate (EDTA) titrant (95–99% as Y 4− anion) precipitates with Ag + cations to form the Ag 4Y species, in aqueous medium, which is well characterized from conductometric titration, thermal analysis and potentiometric titration of the silver content of the solid. The precipitate dissolves in excess Y 4− to form a complex, AgY 3−. Equilibrium studies at 25°C and ionic strength 0.50 M (NaNO 3) have shown from solubility and potentiometric measurements that the formation constant (95% confidence level) β 1 = (1.93 ± 0.07) × 10 5 M −1 and the solubility products are KS0 = [Ag +] 4[Y 4−] = (9.0 ± 0.4) × 10 −18 M 5 and KS1 = [Ag +] 3[AgY 3−] = (1.74 ± 0.08) × 10 −12 M4. The presence of Na +, rather than ionic strength, markedly affects the equilibrium; the data at ionic strength 0.10 M are: β 1 = (1.19 ± 0.03) × 10 6 M −1, KS0 = (1.6 ± 0.4) × 10 −19 M 5 and KS1 = (1.9 ± 0.5) × 10 −13 M 4; at ionic strength tending to zero; β 1 = (1.82 ± 0.05) × 10 7 M −1, KS0 = (2.6 ± 0.8) × 10 −22 M 5 and KS1 = (5 ± 1) × 10 −15 M 4. The intrinsic solubility is 2.03 mM silver (I) in 0.50 M NaNO 3. Well-defined potentiometric titration curves can be taken in the range 1–2 mM with the Ag indicator electrode. Thermal analysis revealed from differential scanning calorimetry a sharp exothermic peak at 142°C; thermal gravimetry/differential thermal gravimetry has shown mass loss due to silver formation and a brown residue, a water-soluble polymeric acid (decomposition range 135–157°C), tending to pure silver at 600°C, consistent with the original Ag 4Y salt. 相似文献
3.
The generality of a two-electron reduction process involving an
mechanism has been established for M 3(CO) 12 and M 3(CO) 12− n(PPh 3) n (M = Ru, Os) clusters in all solvents. Detailed coulometric and spectral studies in CH 2Cl 2 provide strong evidence for the formation of an ‘opened’ M 3(CO) 122− species the triangulo radical anions M 3(CO) 12−· having a half-life of < 10 −6 s in CH 2Cl 2. However, the electrochemical response is sensitive to the presence of water and is concentration dependent. An electrochemical response for “opened” M 3(CO) 122− is only detected at low concentrations < 5 × 10 −4 mol dm −3 and under drybox conditions. The electroactive species ground at higher concentrations and in the presence of water M 3(CO) 112− and M 6(CO) 182− were confirmed by a study of the electrochemistry of these anions in CH 2Cl 2; HM 3(CO) 11− is not a product. The couple [M 6(CO) 18] −/2− is chemically reversible under certain conditions but oxidation of HM 3(CO) 11− is chemically irreversible. Different electrochemical behaviour for Ru 3(CO) 12 is found when [PPN][X] (X = OAc −, Cl −) salts are supporting electrolytes. In these solutions formation of the ultimate electroactive species [μ-C(O)XRu 3(CO) 10] − at the electrode is stopped under CO or at low temperatures but Ru 3(CO) 12−· is still trapped by reversible attack by X presumably as [η 1-C(O)XRu 3(CO) 11] −. It is shown that electrode-initiated electron catalysed substitution of M 3(CO) 12 only takes place on the electrochemical timescale when M = Ru, but it is slow, inefficient and non-selective, whereas BPK-initiated nucleophilic substitution of Ru 3(CO) 12 is only specific and fast in ether solvents particulary THF. Metal---metal bond cleavage is the most important influence on the rate and specificity of catalytic substitution by electron or [PPN]-initiation. The redox chemistry of M 3(CO) 12 clusters (M = Fe, Ru, Os) is a consequence of the relative rates of metal---metal bond dissociation, metal-metal bond strength and ligand dissociation and in many aspects resembles their photochemistry. 相似文献
4.
The one-electron oxidation of Mitomycin C (MMC) as well as the formation of the corresponding peroxyl radicals were investigated by both steady-state and pulse radiolysis. The steady-state MMC-radiolysis by OH-attack followed at both absorption bands showed different yields: at 218 nm G i (-MMC) = 3.0 and at 364 nm G i (-MMC) = 3.9, indicating the formation of various not yet identified products, among which ammonia was determined, G(NH 3) = 0.81. By means of pulse radiolysis it was established a total κ (OH + MMC) = (5.8 ± 0.2) × 10 9 dm 3 mol −1 s −1. The transient absorption spectrum from the one-electron oxidized MMC showed absorption maxima at 295 nm (ε = 9950 dm 3 mol −1 cm t-1), 410 nm (ε = 1450 dm 3 mol −1 cm −1) and 505 nm ( ε = 5420 dm 3 mol −1 cm −1). At 280–320 and 505 nm and above they exhibit in the first 150 μs a first order decay, κ 1 = (0.85 ± 0.1) × 10 3 s −1, and followed upto ms time range, by a second order decay, 2κ = (1.3 ± 0.3) × 10 8 dm 3 mol -1 s −1. Around 410 nm the kinetics are rather mixed and could not be resolved. The steady-state MMC-radiolysis in the presence of oxygen featured a proportionality towards the absorbed dose for both MMC-absorption bands, resulting in a Gi (-MMC) = 1.5. Among several products ammonia-yield was determined G(NH3) = 0.52. The formation of MMC-peroxyl radicals was studied by pulse radiolysis, likewise in neutral aqueous solution, but saturated with a gas mixture of 80% N2O and 20% O2. The maxima of the observed transient spectrum are slightly shifted compared to that of the one-electron oxidized MMC-species, namely: 290 nm (ε = 10100 dm3 mol−1 cm−1), 410 nm (ε = 2900 dm3 mol−1 cm−1) and 520 nm (ε = 5500 dm3 mol−1 cm−1). The O2-addition to the MMC-one-electron oxidized transients was found to be at 290 to 410 nm gk(MMC·OH + O2) = 5 × 107 dm3 mol−1 s−1, around 480 nm κ = 1.6 × 108 dm3 mol−1 s−1 and at 510 nm and above, κ = 3 × 108 dm3 mol−1 s−1. The decay kinetics of the MMC-peroxyl radicals were also found to be different at the various absorption bands, but predominantly of first order; at 290–420 nm κ1 = 1.5 × 103 s−1 and at 500 nm and above, κ = 7.0 × 103 s−1. The presented results are of interest for the radiation behaviour of MMC as well as for its application as an antitumor drug in the combined radiation-chemotherapy of patients. 相似文献
5.
A new bulk acoustic wave (BAW) cellulase sensing technique, which is based on the enzymatic hydrolysis process of sodium carboxymethylcellulose (CMC) by cellulase, was established. The frequency shift curves of BAW sensor indicated that the viscosity of the tested solutions decreased during the hydrolysis process. The hydrolysis rate of CMC by cellulase was calculated from the frequency shift curves. The hydrolysis rate of CMC under different pH conditions at 30°C showed that cellulase had high hydrolysis ability approximately at pH 5.0. Kinetic parameters (the Michaelis constant Km and the maximum rate Vmax) of the process were estimated by using a linear method of Lineweaver–Burk plot. Km is 1.95±0.25 mg ml −1 and Vmax is −(4.25±0.58)×10 −3 g 1/2 cm −3/2 cP 1/2 min −1. Also the activation energy ( Ea) of the enzymatic hydrolysis, with a value of 51.99±1.26 kJ mol −1, was estimated in this work. 相似文献
6.
The reaction of the anionic mononuclear rhodium complex [Rh(C 6F 5) 3Cl(Hpz)] t- (Hpz = pyrazole, C 3H 4N 2) with methoxo or acetylacetonate complexes of Rh or Ir led to the heterodinuclear anionic compounds [(C 6F 5) 3Rh(μ-Cl)(μ-pz)M(L 2)] [M = Rh, L 2 = cyclo-octa-1,5-diene, COD (1), tetrafluorobenzobarrelene, TFB (2) or (CO) 2 (4); M = Ir, L 2 = COD (3)]. The complex [Rh(C 6F 5) 3(Hbim)] − (5) has been prepared by treating [Rh(C 6F 5) 3(acac)] − with H 2bim (acac = acetylacetonate; H 2bim = 2,2′-biimidazole). Complex 5 also reacts with Rh or Ir methoxo, or with Pd acetylacetonate, complexes affording the heterodinuclear complexes [(C 6F 5) 3Rh(μ-bim)M(L 2)] − [M = Rh, L 2 = COD (6) or TFB (7); M = Ir, L 2 = COD (8); M = Pd, L 2 = η 3-C 3H 5 (9)]. With [Rh(acac)(CO) 2], complex 5 yields the tetranuclear complex [{(C 6F 5) 3Rh(μ-bim)Rh(CO) 2} 2] 2−. Homodinuclear Rh III derivatives [{Rh(C 6F 5) 3} 2(μ-L) 2] ·- [L 2 = OH, pz (11); OH, S tBu (12); OH, SPh (13); bim (14)] have been obtained by substitution of one or both hydroxo groups of the dianion [{Rh(C 6F 5) 3(μ-OH)} 2] 2− by the corresponding ligands. The reaction of [Rh(C 6F 5) 3(Et 2O) x] with [PdX 2(COD)] produces neutral heterodinuclear compounds [(C 6F 5) 3Rh(μ-X) 2Pd(COD)] [X = Cl (15); Br (16)]. The anionic complexes 1–14 have been isolated as the benzyltriphenylphosphonium (PBzPh 3+) salts. 相似文献
7.
Recent results (post-1990) on the synthesis and structures of bis(trimethylsilyl)methyls M(CHR 2) m (R = SiMe 3) of metals and metalloids M are described, including those of the crystalline lipophilic [Na(μ-CHR 2)] ∞, [Rb(μ-CHR 2)(PMDETA)] 2, K 4(CHR 2) 4(PMDETA) 2, [Mg(CHR 2)(μ-CHR 2)] ∞, P(CHR 2) 2 (gaseous) and P 2(CHR 2) 4, [Yb(CHR 2) 2(OEt 2) 2] and [{Yb(CR 3)(μ-OEt)(OEt 2)} 2]; earlier information on other M(CHR 2) m complexes and some of their adducts is tabulated. Treatment of M(CHR 2) (M = Li or K) with four different nitriles gave the X-ray-characterized azaallyls or β-diketinimates
,
and
(LL′ = N(R)C( tBu)CHR, L′L′ = N(R)C(Ph)C(H)C(Ph)NR, LL″ = N(R)C(Ph)NC(H)C(Ph)CHR, R = SiMe 3 and Ar = C 6H 3Me 2-2,5). The two lithium reagents were convenient sources of other metal azaallyls or β-diketinimates, including those of K, Co(II), Zr(IV), Sn(IV), Yb(II), Hf(IV) and U(VI)/U(III). Complexes having one or more of the bulky ligands [LL′] −, [L′L′] −, [LL] −, [LL″] −, [L″L] −, [LL] − and [{N(R)C( tBu)CH} 2C 6H 4-2] 2− are described and characterized (LL = N(H)C(Ph)C(H)C(Ph)NH, L″L = N(R)C( tBu)C(H)C(Ph)NR, LL = N(R)C( tBu)CHPh). Among the features of interest are (i) the contrasting tetrahedral or square-planar geometry for
and
, respectively, and (ii) olefin-polymerization catalytic activity of some of the zirconium(IV) chlorides. 相似文献
8.
Medium-resolution spectra of the N 2 b 1Π u-X 1Σ g+ band system were recorded by 1 + 1 multiphoton ionization. In the spectra we found different linewidths for transitions to different vibrational levels in the b 1Π u state: Δν 0 = 0.50 ± 0.05 cm −1, Δν 1 = 0.28 ± 0.02 cm −1, Δν 2 = 0.65 ± 0.06 cm −1, Δν 3 = 3.2 ± 0.5 cm −1, Δν 4 = 0.60 ± 0.07 cm −1, and Δν 5 = 0.28 ± 0.02 cm −1. From these linewidths, predissociation lifetimes τ ν were obtained: τ 0 = 16 ± 3 ps, τ 1 > 150 ps, τ 2 = 10 ± 2 ps, τ 3 = 1.6 ± 0.3 ps, τ 4 = 9 ± 2 ps, and τ 5 > 150 ps. Band origins and rotational constants for the b 1Π uν = 0 and 1 levels were determined for the 14N 2 and 14N 15N molecules. 相似文献
9.
Electrochemical measurements were performed to investigate the effectiveness of cationic surfactants of the N-alkyl quaternary ammonium salt type, i.e. myristyltrimethylammonium chloride (MTACl), cetyldimethylbenzylammonium chloride (CDBACl), and trioctylmethylammonium chloride (TOMACl), as corrosion inhibitors for type X4Cr13 ferritic stainless steel in 2 M H 2SO 4 solution. Potentiodynamic polarization measurements showed that these surfactants hinder both anodic and cathodic processes, i.e. act as mixed-type inhibitors. It was found that the adsorption of the N-alkyl ammonium ion in 2 M H 2SO 4 solution follows the Langmuir adsorption isotherm. Plots of log [ θ/(1 − θ)] versus log cinh yielded straight lines with a slope, which changed drastically at the critical micelle concentration (CMC) of the surfactants studied. Accordingly, the CMC could be accurately determined from these measurements. The calculated values of the free energy of adsorption Δ Gads are, in cases when the charge on the metal surface is negative with respect to the PZC, relatively high what is characteristically for the chemisorption. On the other hand, for positive metal surfaces it is assumed that SO 42− anions are adsorbed first, so the cationic species would be limited by the surface concentration of anions. Accordingly Δ Gads values were lower in this case and the adsorption is due to merely electrostatic attraction, which is characteristically of physisorption. 相似文献
10.
A thin, gas-tight palladium (Pd) membrane was prepared by the counter-diffusion chemical vapor deposition (CVD) process employing palladium chloride (PdCl 2) vapor and H 2 as Pd precursors. A disk-shaped, two-layer porous ceramic membrane consisting of a fine-pore γ-Al 2O 3 top layer and a coarse-pore -Al 2O 3 substrate was used as Pd membrane support. A 0.5–1 μm thick metallic membrane was deposited in the γ-Al 2O 3 top layer very close to its surface, as verified by XRD and SEM with a backscattered electron detector. The most important parameters that affected the CVD process were reaction temperature, reactants concentrations and top layer quality. Deposition of Pd in the γ-Al 2O 3 top layer resulted in a 100- to 1000-fold reduction in He permeance of the porous substrate. The H 2 permeation flux of these membranes was in the range 0.5–1.0 × 10 −6 mol m −2 s −1 Pa −1 at 350–450°C. The H 2 permeation data suggest that surface reaction steps are rate-limiting for H 2 transport through such thin membranes in the temperature range studied. 相似文献
11.
The hydrothermal reactions of vanadium oxide starting materials with divalent transition metal cations in the presence of nitrogen donor chelating ligands yield the bimetallic cluster complexes with the formulae [{Cd(phen 2) 2V 4O 12]·5H 2O (1) and [Ni(phen) 3] 2[V 4O 12]·17.5H 2O (2). Crystal data: C 48H 52Cd 2N 8O 22V 4 (1), triclinic.
a=10.3366(10), b=11.320(3), c=13.268(3) Å, =103.888(17)°, β=92.256(15)°, γ=107.444(14)°, Z=1; C 72H 131N 12Ni 2O 29.5V 4 (2), triclinic.
a=12.305(3), b=13.172(6), c=15.133(4), =79.05(3)°, β=76.09(2)°, γ=74.66(3)°, Z=1. Data were collected on a Siemens P4 four-circle diffractometer at 293 K in the range 1.59° <θ<26.02° and 2.01°<θ<25.01° using the ω-scan technique, respectively. The structure of 1 consists of a [V 4O 12] 4− cluster covalently attached to two {Cd(phen) 2} 2+ fragments, in which the [V 4O 12] 4− cluster adopts a chair-like configuration. In the structure of 2, the [V 4O 12] 4− cluster is isolated. And the complex formed a layer structure via hydrogen bonds between the [V 4O 12] 4− unit and crystallization water molecules. 相似文献
12.
At 25°C, I = 1.0 M (CF 3SO 3−Li ++CF 3SO 3H), [H +] = 0.034–0.274 M and λ = 453 nm, the rate equation for the oxidation of Ti(H 2O), 63+ by bromine was found to be: −d/[Br 2] T/d t= kK/[Br 2][Ti III]/[H +]+ K+ kK/[Br 3−][Ti III]/[H ++ K, where k = 9.2 × 10 −3 M −1 s −1 and K = 4.5 × 10 −3 M. At [H +] = 1.0 M, [Br −] = 0.05–0.4 M, the apparent second-order rate constant decreases as [Br −] increases. The pH-dependence of the oxidation of TiIII-edta by bromine is interpreted in terms of the change in identity of the TiIII-edta species as the pH of the reaction medium changes. The second-order rate constants were fitted using a non-linear least-square computer program with (1/k0edta)2 weighting into an equation of the form: k0edta =k1+k2K1[H+]−1+k3K1K2[H+]−2/1+K1[H+[H+−1+K1K2[H+]−2, with K1 and K2 fixed as earlier determined at 9.55 × 10−3 and 2.29 × 10−9 M, respectively, for the oxidation of bromine. k1=k2=(3.1±0.32)×103M−1s−1 k3=(2.3±0.45)×106N−1s−1. It is proposed that these electron transfer reactions proceed by univalent changes with the production of Br2.− as a transient intermediate. An outer-sphere mechanism is proposed for these reactions. The homonuclear exchange rate for TiIII-edta+TiIV-edta is estimated at 32 M−1 s−1. 相似文献
13.
Reaction of [Pt 2(η 5-C 5Me 5) 2(η-Br) 3] 3+(Br −) 3 with C 5R 5H (R = H,Me) in the presence of AgBF 4 gives the first platinocenium dications, [Pt(η 5-C 5Me 5)(η 5-C 5R 5)] 2+(BF 4− ) 2. On electrochemical reduction, [pt(η 5-C 5Me 5) 2] 2+ yields [Pt(η 4-C 5Me 5H)(η 2-C 5Me 5)]+ BF 4−. kw]Cyclopentadienyl; Metallocenes; Platinum; Electrochemistry 相似文献
14.
The crystal structures of propionaldehyde complex ( RS, SR)-(η 5-C 5H 5)Re(NO)(PPh 3)(η 2-O=CHCH 2CH 3)] + PF 6− (1b + PF 6s−; monoclinic, P2 1/ c (No. 14), a = 10.166 (1) Å, b = 18.316(1) Å, c = 14.872(2) Å, β = 100.51(1)°, Z = 4) and butyraldehyde complex ( RS, SR)-[(η 5-C 5H 5)Re(NO)(PPh 3)(η 2-O=CHCH 2CH 2CH 3)] + PF 6− (1c +PF 6−; monoclinic, P2 1/ a (No. 14), a = 14.851(1) Å, b = 18.623(3) Å, c = 10.026(2) Å, β = 102.95(1)°, Z = 4) have been determined at 22°C and −125°C, respectively. These exhibit C
O bond lengths (1.35(1), 1.338(5) Å) that are intermediate between those of propionaldehyde (1.209(4) Å) and 1-propanol (1.41 Å). Other geometric features are analyzed. Reaction of [(η 5-C 5H 5)Re(NO)(PPh 3)(ClCH 2Cl)] + BF 4− and pivalaldehyde gives [(η 5-C 5H 5)Re(NO)(PPh 3)(η 2-O=CHC(CH 3) 3)] +BF 4− (81%), the spectroscopic properties of which establish a π C
O binding mode. 相似文献
15.
A series of γ-Al 2O 3 samples modified with various contents of sulfate (0–15 wt.%) and calcined at different temperatures (350–750 °C) were prepared by an impregnation method and physically admixed with CuO–ZnO–Al 2O 3 methanol synthesis catalyst to form hybrid catalysts. The direct synthesis of dimethyl ether (DME) from syngas was carried out over the prepared hybrid catalysts under pressurized fixed-bed continuous flow conditions. The results revealed that the catalytic activity of SO 42−/γ-Al 2O 3 for methanol dehydration increased significantly when the content of sulfate increased to 10 wt.%, resulting in the increase in both DME selectivity and CO conversion. However, when the content of sulfate of SO 42−/γ-Al 2O 3 was further increased to 15 wt.%, the activity for methanol dehydration was increased, and the selectivity for DME decreased slightly as reflected in the increased formation of byproducts like hydrocarbons and CO 2. On the other hand, when the calcination temperature of SO 42−/γ-Al 2O 3 increased from 350 °C to 550 °C, both the CO conversion and the DME selectivity increased gradually, accompanied with the decreased formation of CO 2. Nevertheless, a further increase in calcination temperature to 750 °C remarkably decreased the catalytic activity of SO 42−/γ-Al 2O 3 for methanol dehydration, resulting in the significant decline in both DME selectivity and CO conversion. The hybrid catalyst containing the SO 42−/γ-Al 2O 3 with 10 wt.% sulfate and calcined at 550 °C exhibited the highest selectivity and yield for the synthesis of DME. 相似文献
16.
Using N •3 species as specific electron acceptor a defined ascorbate radical: AH •↔A •−+H + (λ max=360 nm, =3400 dm 3 mol −1 cm −1) is observed. The attack of DMSO •+ on vit.E results in a vit.E • radical ( k=1×10 9 dm 3 mol −1 s −1; λ max=425 nm, =2400 dm 3 mol −1 cm −1; 2 k=4.7×10 8 dm 3 mol −1 s −1). Vit.E-acetate leads to the formation of a radical cation (vit.E-ac •+). β-carotene reacts also with DMSO •+ forming a radical cation, β-car •+ ( k=1.75×10 8 dm 3 mol −1 s −1; λ max=942 nm, =14 600 dm 3 mol −1 cm −1), which probably leads to the formation of a dimer radical cation, (β-car) •+2 ( k=2.5×10 7 dm 3 mol −1 s −1). Using E.coli bacteria (AB1157) as a model system in vitro it was found that all three vitamins are rather efficient radiation protecting agents. They can also increase the activity of cytostatica, e.g., mitomycin C (MMC), by electron transfer process. The mixture of vit.E-ac and β-car acts contradictory, but adding vit.C to it a strong cooperative enhancement of the MMC activity is observed once again. A relationship between the pulse radiolysis and the radiation biological data is found and discussed. A possible explanation of the previously reported trials concerning the role of vit.E and β-car on the increased occurence of lung and other types of cancer in smokers and drinkers is presented. 相似文献
17.
Treatment of [Ru 2(CO) 4(MeCN) 6][BF 4] 2 or [Ru 2(CO) 4(μ-O 2CMe) 2(MeCN) 2] with uni-negative 1,1-dithiolate anions via potassium dimethyldithiocarbamate, sodium diethyldithiocarbamate, potassium tert-butylthioxanthate, and ammonium O, O′-diethylthiophosphate gives both monomeric and dimeric products of cis-[Ru(CO) 2(η 2-(SS)) 2] ((SS) −=Me 2NCS 2− (1), Et 2NCS 2− (2), tBuSCS 2− (3), (EtO) 2PS 2− (4)) and [Ru(CO)(η 2-(Me 2NCS 2))(μ,η 2-Me 2NCS 2)] 2 (5). The lightly stabilized MeCN ligands of [Ru 2(CO) 4(MeCN) 6][BF 4] 2 are replaced more readily than the bound acetate ligands of [Ru 2(CO) 4(μ-O 2CMe) 2(MeCN) 2] by thiolates to produce cis-[Ru(CO) 2(η 2-(SS)) 2] with less selectivity. Structures 1 and 5 were determined by X-ray crystallography. Although the two chelating dithiolates are cis to each other in 1, the dithiolates are trans to each other in each of the {Ru(CO)(η 2-Me 2NCS 2) 2} fragment of 5. The dimeric product 5 can be prepared alternatively from the decarbonylation reaction of 1 with a suitable amount of Me 3NO in MeCN. However, the dimer [Ru(CO)(η 2-Et 2NCS 2)(μ,η 2-Et 2NCS 2)] 2 (6), prepared from the reaction of 2 with Me 3NO, has a structure different from 5. The spectral data of 6 probably indicate that the two chelating dithiolates are cis to each other in one {Ru(CO)(η 2-Et 2NCS 2) 2}fragment but trans in the other. Both 5 and 6 react readily at ambient temperature with benzyl isocyanide to yield cis-[Ru(CO)(CNCH 2Ph)(η 2-(SS)) 2] ((SS)=Me 2NCS 2− (7) and Et 2NCS 2− (8)). A dimerization pathway for cis-[Ru(CO) 2(η 2-(SS)) 2] via decabonylation and isomerization is proposed. 相似文献
18.
The spectrum of CD 2HF was measured by high-resolution interferometric Fourier-transform IR (FTIR) spectroscopy (apodised instrumental band with:0.004 cm −1 fwhm) between 800 and 1200 cm −1 covering the four lowest fundamentals. A complete rotational analysis using a semi-automatic assignment procedure yields accurate band centres (ν 9: 912.2028 cm −1, ν 6:964.4994 cm −1, ν 5: 1050.5104 cm −1, ν 4: 1093.8632 cm −1) and a complete set of first-order Coriolis coupling constants. The most important couplings occur between ν 9 and ν 6 (ξ a= 1.069 cm −1, ξ c= −0.3535 cm −1) and between ν 5 and ν 4 (ξ b= −0.80606 cm −1). The analysis was guided by and compared with results from our ab initio calculations for Coriolis constants and transition moments using CADPAC at TZP/MP2 level. 相似文献
19.
The reaction of {HB(Me 2pz) 3}Mo(NCS)(S 4) [HB(Me 2pz) 3− = hydrotris(3,5-dimethylpyrazolyl)borate anion] with dicarbomethoxyacetylene in refluxing toluene results in the formation of the brown, diamagnetic complex {HB(Me 2pz) 3}Mo(NCS){S 2C 2(CO 2Me) 2} (1) (the reactants above also yield 1 upon prolonged reaction in dichloromethane at 25°C), which has been characterized by X-ray crystallography. The mononuclear pseudo-octahedral complex contains a facially tridentate HB(Me 2pz) 3− ligand, a monodentate N-bound NCS − ligand, and a bidentate S 2C 2(CO 2Me) 22− ligand having a near planar MoS 2C 4 fragment and a SC=CS bond distance of 1.342(15) Å. Solutions of 1 are unstable in air and decompose to produce {HB(Me 2pz) 3}MoO 2(NCS) and {HB(Me 2pz) 3}MoO(NCS) 2. 相似文献
20.
The coordinatively unsaturated cluster [Pt 3(μ 3-CO)(μ-dppm) 3] 2+ (1, dppm = Ph 2PCH 2PPh 2) reacts with Na +[M(CO) 5] − to give the mixed metal clusters [Pt 3{M(CO) 3}(μ-dppm) 3] + (M = Re, 2; Mn, 3). The new clusters are characterized by spectroscopic methods and, for M = Re, by an X-ray structure determination. The Pt 3Re core in 2 is tetrahedral with particularly short metal-metal distances. 相似文献
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