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1.
The oxygen permeation properties of mixed-conducting ceramics SrFeCo 0.5O 3−δ (SFCO), Ba 0.5Sr 0.5Co 0.8Fe 0.2O 3−δ (BSCFO), La 0.2Sr 0.8Co 0.8Fe 0.2O 3−δ (LSCFO) and Ba 0.95Ca 0.05Co 0.8Fe 0.2O 3−δ (BCCFO) were studied by thermogravimetric method in the temperature range 600–900 °C. The results show that the oxygen adsorption rate constants ka of all material are larger than oxygen desorption rate constants kd and both ka and kd are not strongly dependent on temperature in the studied temperature range. The oxygen vacancy contents δ(N 2) and δ(O 2) in nitrogen and oxygen and their difference Δ δ = δ(N 2) − δ(O 2) play an important role in determining the temperature behavior of oxygen permeation flux JO2. 相似文献
2.
The reaction products of palladium atoms with molecular oxygen in solid argon have been investigated using matrix isolation infrared absorption spectroscopy and quantum chemical calculations. In addition to the previously reported mononuclear palladium–dioxygen complexes: Pd(η 2–O 2) and Pd(η 2–O 2) 2, dinuclear palladium–dioxygen complexes: Pd 2(η 2–O 2) and Pd 2(η 2–O 2) 2 were formed under visible light irradiation and were identified on the basis of isotopic substitution and theoretical calculations. In addition, experiments doped with xenon in argon coupled with theoretical calculations suggest that the Pd(η 2–O 2), Pd 2(η 2–O 2) and Pd 2(η 2–O 2) 2 complexes are coordinated by two argon or xenon atoms in solid argon matrix, and therefore, should be regarded as the Pd(η 2–O 2)(Ng) 2, Pd 2(η 2–O 2)(Ng) 2 and Pd 2(η 2–O 2) 2(Ng) 2 (NgAr or Xe) complexes isolated in solid argon. 相似文献
3.
Oxidative addition of ethyl iodide to PdMe 2(2,2′-bipyridyl) in (CD 3) 2CO gives the unstable “PdIMe 2Et(bpy)”, which undergoes reductive elimination to form PdIR(bpy) (R = Me, Et), ethane, and propane. Ethene and palladium metal are also formed, and are attributed to decomposition of PdIEt(bpy) via β-elimination. Similar results are obtained with n-propyl iodide, although a palladium(IV) intermediate was not detected, but CH 2=CHCH 2X (X = Br, I) and PhCH=CHCH 2Br give isolable complexes fac-PdXMe 2(CH 2CH=CHR)(L 2) (R = H, Ph; L 2 = bpy, phen). The propenyl complexes decompose at ambient temperature to form ethane, a trace of PdXMe(L 2), and mixtures of [Pd(η 3-C 3H 5)(L 2)]X and [Pd(η 3-C 3H 5)(L 2)]-[Pd(η 3-C 3H 5)X 2]; for fac-PdBrMe 2(CH 2CH=CH 2)(bpy) the major palladium(II) product is [Pd(η 3-C 3H 5)(bpy)]Br. 相似文献
4.
Triruthenium clusters containing a methylphenylsulfoximido cap or bridge, Ru 3(CO) 9(μ 2-H)[μ 3-NS(O)MePh] (1), Ru 3(CO) 10(μ 2-H)[μ 3-NS(O)MePh] (2), Ru 3(CO) 8(μ 3-η 2-CPhCHBu)[μ 3-NS(O)MePh] (3), Ru 3(CO) 9(μ 3-η 2-PhCCCCHPh)[μ 2-NS(O)MePh] (4), and Ru 3(CO) 7(μ 2-CO)(μ 3-η 2-PhCCCCHPh)[μ 3-NS(O)MePh] (5) have been examined by EHT and DFT calculations in order to analyze the bonding present in the clusters and to establish the electron counting. They clearly show that a μ 3-sulfoximido group is not a 3e − ligand as one may be led to think at first sight, but rather acts as a three-orbital/5e − system, i.e. should be considered as isolobal to an N---R − ligand. Because of some delocalization of its π-type orbitals on the sulfur and oxygen atoms, it is expected to bind slightly less strongly to metal atoms than classical imido ligands. Once in a μ 2 coordination mode, the sulfoximido ligand retains a lone pair on its pyramidalized N atom and becomes a two-orbital/3e − ligand. It follows that clusters 1, 2, 4 and 5 are electron-precise, whereas cluster 3 is electron deficient with respect to the 18e − rule but obeys the polyhedral skeletal electron pair electron-counting rules. Consistently, all the calculated clusters exhibit large HOMO–LUMO gaps and no trace of electron deficiency can be found in their electronic structures. 相似文献
5.
The reactions of the half-sandwich molybdenum(III) complexes CpMo(η 4-C 4H 4R 2)(CH 3) 2, where Cp=η 5-C 5H 5 and R=H or CH 3, with equimolar amounts of B(C 6F 5) 3 have been investigated in toluene. EPR monitoring shows the formation of an addition product which does not readily react with Lewis bases such as ethylene, pyridine, or PMe 3. The analysis of the EPR properties and the X-ray structure of a decomposition product obtained from dichloromethane, [CpMo(η 4-C 4H 6)(μ-Cl)(μ-CH 2)(O)MoCp][CH 3B(C 6F 5) 3], indicate that the borane attack has occurred at the methyl position. 相似文献
6.
The synthesis and reactivity of {(η 5-C 5H 4SiMe 3) 2Ti(CCSiMe 3) 2} MCl 2 (M = Fe: 3a; M = Co: 3b; M = Ni: 3c) is described. The complexes 3 are accessible by the reaction of (η 5-C 5H 4SiMe 3) 2Ti(CSiMe 3) 2 (1) with equimolar amounts of MCl 2 (2) (M = Fe, Co, Ni). 3a reacts with the organic chelat ligands 2,2′-dipyridyl (dipy) (4a) or 1,10-phenanthroline (phen) (4b) in THF at 25°C to afford in quantitative yields (η 5-C 5H 4SiMe 3) 2Ti(CSiMe 3) 2 (1) and [Fe(dipy) 2]Cl 2 (5a) or [Fe(phen) 2]Cl 2 (5b). 1/ n[Cu IHal] n (6) or 1/ n[Ag IHal] n (7) (Hal = Cl, Br) react with {(η 5 -C 5H 4SiMe 3) 2Ti(CCSiMe 3) 2}FeCl 2 (3a), by replacement of the FeCl 2 building block in 3a, to yield the compounds {(η 5-C 5H 4SiMe 3) 2Ti(C CSiMe 3) 2}Cu IHal (8) or {(η 5-C 5H 4SiMe 3) 2Ti(CSiMe 3) 2}Ag IHal (9) (Hal = Cl, Br), respectively. In 8 and 9 each of the two Me 3SiCC-units is η 2-coordinated to monomeric Cu I Hal or Ag IHal moieties. Compounds 8 and 9 can also be synthesized by the reaction of (η 5-C 5H 4SiMe 3) 2 Ti(CSiMe 3) 2 (1) with 1/ n[Cu IHal] n (6) or 1/ n [Ag IHal] n (7) in excellent yields. All new compounds have been characterized by analytical and spectroscopic data (IR, 1H-NMR, MS). The magnetic moments of compounds 3 were measured. 相似文献
7.
Samples of γ-Mn 2O 3 with various iron contents are obtained by co-precipitation from appropriate amounts of manganese sulphate and ferric nitrate solutions by a concentrated (2.5 N) boiling solution of sodium hydroxide. Thermal analysis, X-ray diffraction and IR spectroscopy of the specimens reveal that the presence of iron in γ-Mn 2O 3 up to 15 to 25 at.% leads to formation of a single phase γ-Mn 2O 3 solid solution, which is partly reduced to Mn 3O 4 around 680 °C and finally transforms to the -Mn 2O 3 phase on heating at or above 950 °C. With increasing iron concentration beyond 25 at.%, the formation of a ferrite phase has been detected in addition to the γ-Mn 2O 3 solid solution. However, this ferrite phase is thermally unstable and breaks down on heating around 600°C. 相似文献
8.
The epoxidation of cyclohexene with hydrogen peroxide in a biphase medium (H 2O/CHCl 3) was carried out with the reaction-controlled phase transfer catalyst composed of quaternary ammonium heteropolyoxotungstates [π-C 5H 5N(CH 2) 15CH 3] 3[PW 4O 16]. A conversion of about 90% and a selectivity of over 90% were obtained for epoxidation of cyclohexene on the catalyst. The fresh catalyst, the catalyst under reaction conditions and the used catalysts were characterized by FT-IR, Raman and 31P NMR spectroscopy. It appears that the insoluble catalyst could degrade into smaller species, [(PO 4){WO(O 2) 2} 4] 3−, [(PO 4){WO(O 2) 2} 2{WO(O 2) 2(H 2O)}] 3−, and [(PO 3(OH)){WO(O 2) 2} 2] 2− after the reaction with hydrogen peroxide and becomes soluble in the CHCl 3 solvent. The active oxygen in the [W 2O 2(O 2) 4] structure unit of these soluble species reacts with olefins to form the epoxides and consequently the corresponding W---Ob---W (corner-sharing) and W---Oc---W (edge-sharing) bonds are formed. The peroxo group [W 2O 2(O 2) 4] can be regenerated when the W---Ob---W and W---Oc---W bonds react with hydrogen peroxide again. These soluble species lose active oxygen and then polymerize into larger compounds with the W---Ob---W and W---Oc---W bonds and then precipitate from the reaction solution after the hydrogen peroxide is consumed up. Part of the used catalyst seems to form more stable compounds with Keggin structure under the reaction conditions. 相似文献
9.
A series of Ce xPr 1−xO 2−δ mixed oxides were synthesized by a sol–gel method and characterized by Raman, XRD and TPR techniques. The oxidation activity for CO, CH 3OH and CH 4 on these mixed oxides was investigated. When the value x was changed from 1.0 to 0.8, only a cubic phase CeO 2 was observed. The samples were greatly crystallized in the range of the value x from 0.99 to 0.80, which is due to the formation of solid solutions caused by the complete insertion of Pr into the CeO 2 crystal lattices. Raman bands at 465 and 1150 cm −1 in Ce xPr 1−xO 2−δ samples are attributed to the Raman active F 2g mode of CeO 2. The broad band at around 570 cm −1 in the region of 0.3 ≤ x ≤ 0.99 can be linked to oxygen vacancies. The new band at 195 cm −1 may be ascribed to the asymmetric vibration caused by the formation of oxygen vacancies. The TPR profile of Pr 6O 11 shows two reduction peaks and the reduction process is followed: . The reduction temperature of Ce xPr 1−xO 2−δ mixed oxides is lower than those of Pr 6O 11 or CeO 2. TPR results indicate that Ce xPr 1−xO 2−δ mixed oxides have higher redox properties because of the formation of Ce xPr 1−xO 2−δ solid solutions. The presence of the oxygen vacancies favors CO and CH 3OH oxidation, while the activity of CH 4 oxidation is mostly related to reduction temperatures and redox properties. 相似文献
10.
The reaction of singlet oxygen with a variety of allyltin compounds CH 2=CHCH 2SnR 3 (R 3 = Me 3, Bu 3, allyl 3, (cyclo-C 6H 113, Ph 3, allylBu 2, Bu 2Cl, Bu 2OAc, allylCl 2, allylCl 2bipy) has been investigated, and the allylperoxytin compounds, 3-stannylallyl hydroperoxides, and 4-stannyl-1,2-dioxolanes which result from M-ene, H-ene and cycloaddition processes, respectively, have been identified by NMR spectroscopy. As the tin centre becomes more electropositive, as indicated by the 13C NMR shift of the allylic CH 2 group, the proportion of the M-ene reaction increases, and when δCH 2 is above about 23.7, the allylperoxytin compound is the only product. An exception to this rule is tetraallyltin, δCH 2 16.13, which similarly shows only the M-ene reaction. This is tentatively ascribed to the special effect of hyperconjugation between the C---Sn σ-bond and the remaining π-systems. A polar solvent favours the M-ene reaction. The cycloaddition reaction is favoured by low temperature, and at − 70°C in a non-polar solvent it may become the major route. Diallylmercury and allylmercury chloride react with singlet oxygen to show only the M-ene reaction, but also undergo extensive photosensitized decomposition. With 4-phenyl-1,2,4-triazoline-3,5-dione (PTAD), allylmercury chloride shows only the M-ene reaction. 相似文献
11.
The chemistry of the di-μ-methylene-bis(pentamethylcyclopentadienyl-rhodium) complexes is reviewed. The complex [{(η 5-C 5Me 5)RhCl 2} 2] (1a) reacted with MeLi to give, after oxidative work-up, blood-red cis-[{(η 5-C 5Me 5)Rh(μ-CH 2)} 2(Me) 2], 2. This has the two rhodiums in the +4 oxidation state ( d5), and linked by a metal-metal bond (2.620 Å). Trans-2 was formed on isomerisation of cis-2 in the presence of Lewis acids, or by direct reaction of 1a with Al 2Me 6, followed by dehydrogenation with acetone. The Rh-methyls in [{(η 5-C 5Me 5)Rh(μ-CH 2)} 2(Me) 2] were readily replaced under acidic conditions (HX) to give [{(η 5-C 5Me 5)Rh(μ-CH 2)} 2(X) 2] (X = Cl, Br or I); these latter complexes reacted with a variety of RMgX to give [{(η 5-C 5Me 5)Rh(μ-CH 2)} 2(R) 2] (R = alkyl, Ph, vinyl, etc.). Trans-2 also reacted with HBF 4 in the presence of L to give first [{(η 5-C 5Me 5)Rh(μ-CH 2)} 2(Me)(L)] + and then [{(η 5-C 5Me 5)Rh(μ-CH 2)} 2(L) 2] 2+ (L = MeCN, CO, etc.). The {(η 5-C 5Me 5)Rh(μ-CH 2)} 2 core is rather kinetically inert and also forms a variety of complexes with oxy-ligands, both cis-, e.g. [{(η 5-C 5Me 5)Rh(μ-CH 2)} 2(μ-OAc)] + and trans-, such as [(η 5-C 5Me 5)Rh(μ-CH 2)} 2(H 2O) 2] 2+. The complexes [{(η 5-C 5Me 5)Rh(μ-CH 2)} 2(R)L] + (R = Me or aryl) in the presence of CO, or [{(η 5-C 4Me 5)Rh(μ-CH 2)} 2(R) 2] (R = Me, Ph or CO 2Me) in the presence of mild oxidants, readily yield the C---C---C coupled products RCH=CH 2. The mechanisms of these couplings have been elucidated by detailed labelling studies: they are more complex than expected, but allow direct analogies to be drawn to C---C couplints that occur during Fischer-Tropsch reactions on rhodium surfaces. 相似文献
12.
A structural study of odd-numbered n-alkane (C n) binary mixtures (C 21 : C 23) was carried out on powder samples using a Guinier-de Wolff camera with increasing concentration of n-C 23 at 293 K. Despite the reports in the literature, these molecular alloys do not form an orthorhombic continuous homogeneous solid solution to C21 from C23 at “low temperature”. Instead, as already observed in two even-numbered Cn systems, X-ray diffraction results show the existence of seven solid solutions as the molar concentration of C23 increases: four terminal solid solutions, denoted β0(C21)β0(C23), isostructural with the “low temperature” phase of pure C21 and C23 (Pbcm), β′0(C21) and β′0(C23), identical to the phase β′0 which appears in pure C23 above the δ transition, and three orthorhombic intermediate solid solutions, designated β″1, β′1 and β″2. On the basis of powder X-ray photographs, the phases β″1 and β″2 (C21 : C23) are indistinguishable, and they are isostructural with the intermediate solid solution β″ of the even-numbered Cn binary systems (C22 : C24) and (C24 : C26). The phase β′1(C21 : C23) is also isostructural with the two indistinguishable intermediate solid solutions β′1 and β′2 of the molecular alloys (C22 : C24) and (24 : C26). From this study and our other laboratory results, the sequences of appearance of the solid solutions and the structural identities between these phases are established at “low temperature” for all the binary molecular alloys of consecutive Cn (odd-odd, even-even or odd-even: 19 < n < 27) when increasing the solute concentration. 相似文献
13.
The compound [RU 3(μ 3,η 2- -ampy)(μ 3η 1:η 2-PhC=CHPh)(CO) 6(PPh 3) 2] (1) (ampy = 2-amino-6-methylpyridinate) has been prepared by reaction of [RU 3(η-H)(μ 3,η 2- ampy) (μ,η 1:η 2-PhC=CHPh)(CO) 7(PPh 3)] with triphenylphosphine at room temperature. However, the reaction of [RU 3(μ-H)(μ 3, η 2 -ampy)(CO) 7(PPh 3) 2] with diphenylacetylene requires a higher temperature (110°C) and does not give complex 1 but the phenyl derivative [RU 3(μ 3,η 2-ampy)(μ,η 1:η 2 -PhC=CHPh)(μ,-PPh 2)(Ph)(CO) 5(PPh 3)] (2). The thermolysis of complex 1 (110°C) also gives complex 2 quantitatively. Both 1 and 2 have been characterized by0 X-ray diffraction methods. Complex 1 is a catalyst precursor for the homogeneous hydrogenation of diphenylacetylene to a mixture of cis- and trans -stilbene under mild conditions (80°C, 1 atm. of H 2), although progressive deactivation of the catalytic species is observed. The dihydride [RU 3(μ-H) 2(μ 3,η 2-ampy)(μ,η 1:η 2- PhC=CHPh)(CO) 5(PPh 3) 2] (3), which has been characterized spectroscopically, is an intermediate in the catalytic hydrogenation reaction. 相似文献
14.
The acid–base chemistry of some ruthenium ethyne-1,2-diyl complexes, [{Ru(CO) 2(η-C 5H 4R)} 2(μ 2-CC)] (R=H, Me) has been investigated. Initial protonation of [{Ru(CO) 2{η-C 5H 4R}} 2(μ 2-CC)] gave the unexpected complex cation, crystallised as the BF 4 salt, [{Ru(CO) 2(η-C 5H 4R}} 3(μ 3-CC)][BF 4] (R=Me structurally characterised). This synthesis proved to be unreliable but subsequent, careful protonation experiments gave excellent yields of the protonated ethyne-1,2-diyl complexes, [{Ru(CO) 2{η-C 5H 4R)} 2(μ 2-η 1:η 2-CCH)](BF 4) (R=Me structurally characterised) which could be deprotonated in high yield to return the starting ethyne-1,2-diyl complexes. 相似文献
15.
The fraction FΣ of excited-state oxygen formed as b 1Σ g+ was determined for a series of triplet-state photosensitizers in CCl 4 solutions. FΣ was determined by monitoring the intensities of (a) O 2(b 1Σ g+) fluorescence at 1926 nm (O 2(b 1Σ g+)→O 2(a 1Δ g) and (b) O 2(a 1 Δ g) phosphorescence at 1270 nm (O 2(a 1Δ g) → O 2(X 3Σ g−)). Oxygen excited states were formed by energy transfer from substituted benzophenones and acetophenones. The data indicate that FΣ depends on several variables including the orbital configuration of the lowest triplet state and the triplet-state energy. The available data indicate that the sensitizer-oxygen charge transfer (CT) state is not likely to influence FΣ strongly by CT-mediated mixing of various sensitizer-oxygen states. 相似文献
16.
Reaction of the ruthenium(IV) chloro-bridged dimer [{Ru(η 3 : η 3-C 10H 16)Cl(μ-Cl)} 2], 1, with ethanethiol (EtSH) in CH 2Cl 2 gives the bridged-cleaved adduct [Ru(η 3 : η 3-C 10H 16)Cl 2(SHEt)], 2. Stirring of two molar equivalents of 2 in methanol with one equivalent of 1 gives the binuclear, mixed chloro/thiolato bridged compound [{Ru(η 3 : η 3-C 10H 16)Cl} 2(μ-SEt)], 3. The related doubly thiolato bridged complex [{Ru(η 3 : η 3-C 10H 10)Cl(μ-SEt)} 2], 4, is formed by treatment of 1 with an excess of EtSH, or by prolonged stirring of 2 alone in methanol. Compounds 2–4 have been studied by cyclic voitammetry. Compound 2 undergoes only irreversible oxidation, whereas in the case of both 3 and 4 the observation of significant return waves is consistent with a greater stability of the primary redox products. 相似文献
17.
Effects of sintering atmospheres on properties of SrCo 0.4Fe 0.5Zr 0.1O 3−δ mixed-conducting membranes were in detail studied in terms of sintering behavior, electrical conductivity and oxygen permeability. The sintering atmospheres were 100% N 2, 79% N 2–21% O 2, 60% N 2–40% O 2, 40% N 2–60% O 2, 20% N 2–80% O 2 and 100% O 2 (in vol.%), and the prepared membranes were correspondingly denoted as S-0, S-21, S-40, S-60, S-80 and S-100, respectively. It was found that the properties of membranes were strongly dependent on the sintering atmosphere. As the oxygen partial pressure in the sintering atmosphere ( PO2) increased, sintering ability, electrical conductivity and oxygen permeability decreased at first, which was in the order of S-0 > S-21 > S-40. However, as PO2 increased further, sintering ability, electrical conductivity and oxygen permeability increased gradually: S-40 < S-60 < S-80 < S-100. And the S-100 membrane had the best sintering ability, electrical conductivity and oxygen permeability in all membranes. 相似文献
18.
The synthesis of the new (η 2-dppe)(η 5-C 5Me 5)Fe---CC---1,3-(C 6H 4X) ( m-2a/2b; X=F/Br) and (η 2-dppe)(η 5-C 5Me 5)Fe---CC---1,4-(C 6H 4I) (2c) complexes, as well as the solid-state structure of the known (η 2-dppe)(η 5-C 5Me 5)Fe---CC---1,4-(C 6H 4F) (2a) complex are described. The catalytic coupling reactions of the bromo complexes with various alkynes were next investigated. Starting from the known (η 2-dppe)(η 5-C 5Me 5)Fe---CC---1,4-(C 6H 4Br) complex (2b), the synthesis of the (η 2-dppe)(η 5-C 5Me 5)Fe---CC---1,4-(C 6H 4)---CC---H complex (6d) and of the corresponding silyl-protected precursors (η 2-dppe)(η 5-C 5Me 5)Fe---CC---1,4-(C 6H 4)CC---SiR 3 (6b/6c; R= iPr/Me) are reported. By use of lithium---bromine exchange reactions on 2b, the silyl- (7a; E=Si; R=Me) and tin- (7b–7d; E=Sn; R=Me, Bu, Ph) substituted analogues (η 2-dppe)(η 5-C 5Me 5)Fe---CC---1,4-(C 6H 4)ER 3 are also isolated. The spectroscopic and electrochemical characterisations of all these new Fe(II)/Fe(III) redox-active building blocks are presented and the electronic substituent parameters for the “(η 2-dppe)(η 5-C 5Me 5)Fe---CC” group are determined by means of 19F-NMR. 相似文献
19.
Binuclear complexes [{Cu(NN)(PhNHpy)} 2(μ-OH) 2](PF 6) 2, where NN=2,2′-bipyridine (bipy) or 1,10-phenanthroline (phen), have been synthesized and characterized by chemical analysis, conductance measurements and IR and electronic spectroscopy. The X-ray crystal structure of [{Cu(bipy)(PhNHpy)} 2(μ-OH) 2](PF 6) 2 shows a distorted square-planar pyramidal coordination for Cu(II), defined by two nitrogen atoms of bipy, two bridging oxygen atoms and the pyridinic nitrogen atom of the ligand. Magnetic susceptibility measurements (in the 4.8–290 K range) reveal coupling which is antiferromagnetic for the bipy complex (2 J=−24.2 cm −1) and slightly ferromagnetic for the phen complex (2 J=3.3 cm −1). The EPR spectra show the expected triplet signals. 相似文献
20.
The reactions of the diruthenium carbonyl complexes [Ru 2(μ-dppm) 2(CO) 4(μ,η 2-O 2CMe)]X (X=BF 4− (1a) or PF 6− (1b)) with neutral or anionic bidentate ligands (L,L) afford a series of the diruthenium bridging carbonyl complexes [Ru 2(μ-dppm) 2(μ-CO) 2(η 2-(L,L)) 2]X n ((L,L)=acetate (O 2CMe), 2,2′-bipyridine (bpy), acetylacetonate (acac), 8-quinolinolate (quin); n=0, 1, 2). Apparently with coordination of the bidentate ligands, the bound acetate ligand of [Ru 2(μ-dppm) 2(CO) 4(μ,η 2-O 2CMe)] + either migrates within the same complex or into a different one, or is simply replaced. The reaction of [Ru 2(μ-dppm) 2(CO) 4(μ,η 2-O 2CMe)] + (1) with 2,2′-bipyridine produces [Ru 2(μ-dppm) 2(μ-CO) 2(η 2-O 2CMe) 2] (2), [Ru 2(μ-dppm) 2(μ-CO) 2(η 2-O 2CMe)(η 2-bpy)] + (3), and [Ru 2(μ-dppm) 2(μ-CO) 2(η 2-bpy) 2] 2+ (4). Alternatively compound 2 can be prepared from the reaction of 1a with MeCO 2H–Et 3N, while compound 4 can be obtained from the reaction of 3 with bpy. The reaction of 1b with acetylacetone–Et 3N produces [Ru 2(μ-dppm) 2(μ-CO) 2(η 2-O 2CMe)(η 2-acac)] (5) and [Ru 2(μ-dppm) 2(μ-CO) 2(η 2-acac) 2] (6). Compound 2 can also react with acetylacetone–Et 3N to produce 6. Surprisingly [Ru 2(μ-dppm) 2(μ-CO) 2(η 2-quin) 2] (7) was obtained stereospecifically as the only one product from the reaction of 1b with 8-quinolinol–Et 3N. The structure of 7 has been established by X-ray crystallography and found to adopt a cis geometry. Further, the stereospecific reaction is probably caused by the second-sphere π–π face-to-face stacking interactions between the phenyl rings of dppm and the electron-deficient six-membered ring moiety of the bound quinolinate (i.e. the N-included six-membered ring) in 7. The presence of such interactions is indeed supported by an observed charge-transfer band in a UV–vis spectrum. 相似文献
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