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1.
LnCl 3 (Ln=Nd, Gd) reacts with C 5H 9C 5H 4Na (or K 2C 8H 8) in THF (C 5H 9C 5H 4 = cyclopentylcyclopentadienyl) in the ratio of 1 : to give (C 5H 9C 5H 4)LnCl 2(THF) n (orC 8H 8)LnCl 2(THF) n], which further reacts with K 2C 8H 8 (or C 5H 9C 5H 4Na) in THF to form the litle complexes. If Ln=Nd the complex (C 8H 8)Nd(C 5H 9C 5H 4)(THF) 2 (a) was obtained: when Ln=Gd the 1 : 1 complex [(C 8H 8)Gd(C %H 9)(THF)][(C 8H 8)Gd(C 5H 9H 4)(THF) 2] (b) was obtained in crystalline form. The crystal structure analysis shows that in (C8H8)Ln(C5H9C5H4)(THF)2 (Ln=Nd or Gd), the Cyclopentylcyclopentadieny (η5), cyclooctatetraenyl (η8) and two oxygen atoms from THF are coordinated to Nd3+ (or Gd3+) with coordination number 10. The centroid of the cyclopentadienyl ring (Cp′) in C5H9C5H4 group, cyclooctatetraenyl centroid (COTL) and two oxygens (THF) form a twisted tetrahedron around Nd3+ (or Gd3+). In (C8H8)Gd(C5H9C5H4)(THF), the cyclopentyl-cyclopentadienyl (η5), cyclooctatetraenyl (η8) and one oxygen atom are coordinated to Gd3+ with the coordination number of 9 and Cp′, COT and oxygen atom form a triangular plane around Gd3+, which is almost in the plane (dev. -0.0144 Å). 相似文献
2.
The C 9–C 21 portion of the aplysiatoxin/oscillatoxin bluegreen algal metabolites was synthesized as the 9-aldehyde bearing a tert-butyldimethylsilyl ether group on the C 11 hydroxyl and a trimethylsilylethoxymethyl ether group on the C 20 hydroxyl. Featuring an asymmetric aldol and an asymmetric oxazaborolldine reduction, the synthesis proceeded with high (>90%) stereoselectivity in 13 steps and 5–7% overall yield from commercial starting material. 相似文献
3.
The spectral analysis indicates that all isomers of C 60O, C 70O and C 60O 2 have an epoxide-like structure (an oxygen atom bridging across a C–C bond). According to the geometrical structure analysis, there are two isomers of fullerene monoxide C 60O (the 5,6 bond and the 6,6 bond), eight isomers of fullerene monoxide C 70O and eight isomers of fullerene dioxide C 60O 2. In order to simulate the real reaction conditions at 300 K, the calculation of the different isomers of C 60O, C 60O 2 and C 70O fullerene oxides was carried out using the semiempirical molecular dynamics method with two different approaches: (a) consideration of the geometries and thermodynamic stabilities, and (b) consideration of the ozonolysis mechanism. According to the semiempirical molecular dynamic calculation analysis, the probable product of this ozonolysis reaction is C 60O with oxygen bridging over the 6–6 bond (C 2v). The most probable product in this reaction contains oxygen bridging across in the upper part of C 70 (6–6 bond in C 70O-2 or C 70O-4) an epoxide-like structure. C 60O 2-1, C 60O 2-3 and C 60O 2-5 are the most probable products for the fullerene dioxides. All of these reaction products are consistent with the experimental results. It is confirmed that the calculation results with the semiempirical molecular dynamics method are close to the experimental work. The semiempirical molecular dynamics method can offer both the reaction temperature effect by molecular dynamics and electronic structure, dipole moment by quantum chemistry calculation. 相似文献
4.
The reaction of [(C 6H 6)RuCl 2] 2 with 7,8-benzoquinoline and 8-hydroxyquinoline in methanol were performed. The obtained complexes have been studied by IR, UV–VIS, 1H and 13C NMR spectroscopy and X-ray crystallography. In the reaction with 8-hydroxyquinoline the arene ruthenium(II) complex oxidized to Ru(III). The electronic spectra of the obtained compounds have been calculated using the TDDFT method. Magnetic properties of [Ru(C 9H 6NO) 3] · CH 3OH complex suggest the antiferromagnetic coupling of the ruthenium centers in the crystal lattice. EPR spectrum of [Ru(C 9H 6NO) 3] · CH 3OH compound indicates single isotropic line only characteristic for Ru 3+ with spin equal to 1/2. 相似文献
5.
Likely candidates for the lowest potential energy minima of (C 60) nCa 2+, (C 60) nF − and (C 60) nI − clusters are located using basin-hopping global optimisation. In each case, the potential energy surface is constructed using the Girifalco form for the C 60 intermolecular interaction, an averaged Lennard–Jones C 60–ion interaction, and a polarisation potential, which depends on the first few non-vanishing C 60 multipole polarisabilities. We find that the ions generally occupy the interstitial sites of a (C 60) n cluster, the coordination shell being tetrahedral for Ca 2+ and F −. The I − ion has an octahedral coordination shell in the global minimum for (C 60) 6I −, however for 12 n 8 the preferred coordination geometry is trigonal prismatic. 相似文献
6.
Effect of solvent polarity on the aggregation behaviour of C 70 has been investigated in several mixed solvents using optical absorption, fluorescence, dynamic light scattering and scanning electron microscopic measurements and compared with those observed for the other fullerene analogue, C 60. It is seen that similar to C 60, aggregation of C 70 also requires the solvent polarity to exceed some critical value. In terms of solvent dielectric constant the critical solvent polarity, required for C 70 aggregation is found to be in the range of 27–31, which is much higher than that required for C 60 aggregation (12–14). The large difference in the critical solvent polarity required for C 60 and C 70 aggregation has been rationalized on the basis of the molecular shapes and the polarizabilities of two fullerene molecules. 相似文献
7.
The stabilities of different isomers of C 60Br n have been calculated for n = 2 to 12. A general stereochemical pattern which emerges is the tendency to form strings created by the edge sharing of C 6Br 2 hexagonal faces. Stable structures are formed if these strings form loops, thereby eliminating string ends, which may involve the creation of C 6Br 3 hexagonal faces. A particularly stable structure is formed at C 60Br 6 in which the loop forms a C 10Br 6 fragment with a pentagonal pyramidal arrangement of six bromine atoms. Two isomers of C 60Br 12 are also particularly stable. One isomer contains two of these Br 6 pentagonal pyramids on opposite sides of the molecule, and the other isomer contains a single large loop wrapped around the middle of the molecule. 相似文献
8.
The pure rotational Raman spectra of C 214N 2 and C 215N 2 have been recorded photographically using a 3-metre spectrograph with a reciprocal linear dispersion of 1.4 cm −1 mm −1 at 488.0 nm and analysed to give the rotational and centrifugal distortion constants for both species. Corrections were applied to compensate for the effect of molecules in excited vibrational states on the pure rotational spectra. Comparisons are made with previous infrared vibration—rotational studies on these species and with previous Raman studies on C 214N 2. The following bond lengths were calculated: r0(C---N) = 116 ± 1 pm; r0(C---C) = 138 ± 2 pm. 相似文献
9.
IR spectroscopy was coupled with the matrix isolation technique to study the molecular complex formed between C 3O 2 and HCl and its photodissociation. The vibrational frequencies of the complex were compared with those of HCl and C 3O 2 monomers. For C 3O 2, a bent structure was characterized in the solid environment. The vibrational frequencies were calculated in the 4000–400 cm−1 range using an ab initio method at the MP2/6-31G** level for the most stable complex; these frequencies describe the hydrogen interaction with the central carbon atom of C3O2 (T complex). The measured shifts between the vibrational mode frequencies of the complex and monomers were in good agreement with the calculated values. Broad-band UV irradiation ( > 230 nm) of the T complex leads preferentially to ketene chloride and carbon monoxide. Ketene chloride formation can be explained by the reaction between HCl and the carbene C2O, which results from photo-dissociation at the C=CO bond of C3O2. 相似文献
10.
The observation of the surface-enhanced vibrational Raman spectra of vapor-deposited C 60 and C 70 on rough silver films is reported. Both near-monolayer and multilayer films of pure C 60 and of C 60/C 70 mixtures are studied. The films are obtained by evaporating fullerene samples at temperatures of 683–875 K in ultra-high vacuum. Mixed fullerene samples were greatly enriched in C 70 by making use of the slightly different vapor pressures of the two major components at the low end of this temperature range. The spectra contain all the lines of the normal Raman spectra as well as several additional lines caused by a reduction in the stringency of the normal Raman selection rules. These results demonstrate the potential of this technique for detecting small quantities of fullerenes and obtaining their vibrational spectra. 相似文献
11.
In the present theoretical work we have explored mechanisms of dissociation reactions of the vinyl radical in the A 2A″ state (C 2H 3 (A 2A″)) and examined possible pathways for nonadiabatic dissociation of C 2H 3 (A 2A″) into C 2H 2 (X 1Σ g+). In the calculations we used the complete active space self-consistent field (CASSCF) and multiconfiguration second-order perturbation theory (CASPT2) methods in conjunction with the cc-pVDZ and cc-pVTZ basis sets. Mechanisms for the following three dissociation channels of C 2H 3 in the A 2A″ state were explored: (1) C 2H 3 (A 2A″) → C 2H 2 ( trans, 3A u) + H, (2) C 2H 3 (A 2A″) → C 2H 2 ( cis, 3A 2) + H, and (3) C 2H 3 (A 2A″) → H 2CC ( 3A 2) + H. The CASSCF and CASPT2 potential energy curve calculations for the C 2H 3 (A 2A″) dissociation channels (1)–(3) indicate that there is neither transition state nor intermediate for each of the channels. At the CASPT2//CASSCF/cc-pVTZ level, the dissociation energies for channels (1)–(3) are predicted to be 84.3, 91.1, and 86.9 kcal/mol, respectively. For a recently observed nonadiabatic dissociation of C 2H 3 (A 2A″) into C 2H 2 (X 1Σ g+) + H [J. Chem. Phys. 111 (1999) 3783], two previously suggested internal conversion (IC) pathways were examined based on our CASSCF and CASPT2 calculations. Our preliminary CASSCF and CASPT2 calculations indicate that the assumed IC pathway via the twisted C 2H 3 (A 2A ′) structure might be feasible. The CASSCF/cc-pVTZ geometry optimization and frequency analysis calculations were performed for the four C 2v bridge structures in the 2B 2, 2A 2, 2B 1, and 2A 1 states along the pathways of the 1 2A ′ (X 2A ′), 1 2A″ (A 2A″), 2 2A″, and 2 2A ′ states of C 2H 3, respectively, and the CASPT2//CASSCF/cc-pVTZ energetic results indicate that the assumed IC pathway, via a C 2v ( 2A 2) structure and then 2A 2/ 2A 1 surface crossing, be not feasible since at their excitation wavelengths (327.4 and 366.2 nm) the C 2v ( 2A 2) structure could not be accessed. 相似文献
12.
A molecular complex of fullerene C 60 with triptycene, TPC·C 60 is obtained. The complex has a three-dimensional packing of C 60 molecules. According to the IR spectra, the freezing of free rotation of C 60 molecules in the complex is maintained up to 360 K. The XP-spectra of TPC·C 60 show the suppression of π–π * transitions of TPC phenylene rings. The separation of C 60 molecules by TPC ones in TPC·C 60 results in low intensity of the C 60 transitions in the 420–500 nm range in an optical spectrum. This absorption is assumed as that attributed to intermolecular transitions between adjacent C 60 molecules. 相似文献
13.
通过将C_9H_(10)O_2-0.5ZnCl_2双酸型低共熔溶剂固载到Al_2O_3上制备了C_9H_(10)O_2-0.5ZnCl_2/Al_2O_3催化剂。该催化剂采用XRD、FT-IR、SEM、EDS、N_2吸附-脱附技术进行了分析。以C_9H_(10)O_2-0.5ZnCl_2/Al_2O_3为催化剂,过氧化氢为氧化剂研究模拟油中芳香族硫化物的脱除性能。考察反应参数如温度、催化剂加入量、O/S物质的量比、硫化物类型等对催化剂脱硫活性的影响。实验结果表明,在模拟油为5 mL、催化剂量为0.2 g、O/S比为8、反应温度为60℃、反应时间为180 min的条件下,模拟油中二苯并噻吩(DBT)脱硫率为99.2%。此外,在模拟油氧化脱硫中催化剂循环使用六次,其氧化脱硫活性略有降低。研究了C_9H_(10)O_2-0.5ZnCl_2/Al_2O_3催化氧化脱硫的反应机理。 相似文献
14.
At present C 94 is one of the highest sets of isomeric fullerenes that has been characterized by 13C NMR spectra. This contribution reports quantum-chemical computations on the C 94 system. The complete set of 134 isolated-pentagon-rule isomers of C 94 is described by four semiempirical quantum-chemical methods (MNDO, AM1, PM3, and SAM1). The C 94 energetics is also checked with Hartree–Fock SCF calculations in the standard 4-31G basis set (HF/4-31G). The calculations point out a C2 structure as the system ground state. As energetics itself cannot produce reliable relative stabilities at high temperatures, entropy terms are also computed and the relative-stability problem is entirely treated in terms of the Gibbs function. The lowest-energy structure remains the most populated isomer at higher temperatures. However, several other structures show significant populations at higher temperatures. The six most populated species at the AM1 computational level read: C2, C2, C1, C1, Cs, and C2. This selected six-membered isomeric set indeed contains the four symmetries observed in the available experiment ( C2, Cs, C2, and C2). This incidence represents a good agreement with the experiment and can be viewed as another evidence that the supposed inter-isomeric thermodynamic equilibrium does exist in experiments. 相似文献
15.
Potential energy surfaces of the reaction of SiH 2 and C 2H 2 (and C 2D 2) have been calculated by means of ab initio molecular orbital theory at the QCISD/6-311G++(2df, 2p)//MP2/6-31G(d, p) level with corrections for the triple excitations to the QCISD energies. The barrier heights for the two reaction channels of the adduct, thus calculated, were further utilized for the dynamical calculation of the rate constants in the framework of quantum statistical Rice-Ramsperger-Kassel theory. Contributions of the rate constants of the various pathways to the total rate constant ( KT) for the disappearance of the reactants are critically examined and compared with experiment. The pressure dependence of KT(C 2H 2) is primarily due to the formation of silirene. KT(C 2D 2) is consistently higher than KT(C 2H 2). The standard heat of formation of silirene is predicted to be 72.1 ± 3 kcal/mol. Rearrangement of silirene to vinylsilylene requires an activation energy smaller than that to silylacetylene. 相似文献
16.
The symmetry unrestricted C 36F 2 isomers formed from fullerene C 36, the initial symmetry of which is C6v, C6h, or D2d, have been extensively studied with semi-empirical (AM1 and PM3) calculations. Based on the relationship between the isomer's stability and the adding positions, three patterns of the adding sites of F 2 moiety in the additive reactions have been deducted. The results of the π-orbital axis vector (POAV) analysis indicate that the chemical reactivity of C 36 is the result of the high strain in the C 36 cage. But, in order to form stable compounds, the effects, which guide the F 2 moiety to select carbon atoms in the C 36 cage, are dominated by the conjugate effect in C 36F 2 system rather than the strain release in the C 36 cage. 相似文献
17.
The details of weak C–H π interactions that control several inter and intramolecular structures have been studied experimentally and theoretically for the 1:1 C 2H 2–CHCl 3 adduct. The adduct was generated by depositing acetylene and chloroform in an argon matrix and a 1:1 complex of these species was identified using infrared spectroscopy. Formation of the adduct was evidenced by shifts in the vibrational frequencies compared to C 2H 2 and CHCl 3 species. The molecular structure, vibrational frequencies and stabilization energies of the complex were predicted at the MP2/6-311+G(d,p) and B3LYP/6-311+G(d,p) levels. Both the computational and experimental data indicate that the C 2H 2–CHCl 3 complex has a weak hydrogen bond involving a C–H π interaction, where the C 2H 2 acts as a proton acceptor and the CHCl 3 as the proton donor. In addition, there also appears to be a secondary interaction between one of the chlorine atoms of CHCl 3 and a hydrogen in C 2H 2. The combination of the C–H π interaction and the secondary ClH interaction determines the structure and the energetics of the C 2H 2–CHCl 3 complex. In addition to the vibrational assignments for the C 2H 2–CHCl 3 complex we have also observed and assigned features owing to the proton accepting C 2H 2 submolecule in the acetylene dimer. 相似文献
18.
Thermal displacement of coordinated nitriles RCN (R = CH 3, C 2H 5 or n-C 3H 7) in [C 5H 5Fe(L 2)(NCR)]X complexes (L 2 = P(OCH 3) 3) 2, (P(OC 6H 5) 3) 2 or (C 6H 5) 2PC 2H 4P(C 6H 5) 2 (DPPE)) by E(CH 3) 2 affords high yields of [C 5H 5Fe(L 2)(E(CH 3) 2)]X compounds (E = S, Se and Te; X = BF 4 or PF 6). Spectroscopic data and ligand displacement reactions are presented and discussed together with related observations on [C 5H 5Fe(CO) 2(E(CH 3) 2)]BF 4 compounds. The molecular structure of [C 5H 5Fe(P(OCH 3) 3) 2(S(CH 3) 2)]PF 6 was determined by a single-crystal X-ray diffraction study: monoclinic, space group P2 1/ n- C52h (No. 14) with a = 8.4064(12), b = 11.183(2), c = 50.726(8) Å, β = 90.672(13)° and Z = 8 molecules per unit cell. The coordination sphere of the iron atom is pseudo-tetrahedral with an Fe---S bond distance of 2.238 Å. 相似文献
19.
采用铜胺配合物(Cu 2+-四乙烯五胺,Cu-TEPA)作为结构导向剂,通过一步水热法合成不同铜铝比(n Cu/n Al)和硅铝比(n Si/n Al)的Cu-SSZ-13分子筛催化剂,研究其在贫燃条件下丙烯选择性催化还原NO(C 3H 6-SCR)的性能。当n Cu/n Al=2、n Si/n Al=6时2.0Cu-SSZ-13(6)催化剂具有最好的低温脱硝活性,200℃时NO转化率超过80%,在250~300℃可实现100%脱硝效率和~100%N 2选择性,同时具有较强的抗水、抗硫性能。为研究不同n Cu/n Al和n Si/n Al对催化剂物理化学特性的影响,通过X射线衍射(XRD)、扫描电子显微镜(SEM)、N 2吸附-脱附测试、H 2程序升温还原(H 2-TPR)、氨气程序升温脱附(NH 3-TPD)、紫外可见光谱(UV-Vis)等手段对样品进行表征。结果表明,2.0Cu-SSZ-13(6)具有最佳的脱硝性能,这是因为其具有最大的比表面积、最强的表面酸性和分布最多的孤立态Cu 2+离子。Cu-SSZ-13上丰富的酸性位可以有效促进C 3H 6和NO的吸附和活化,SSZ-13分子筛八元环中孤立的Cu 2+离子具有良好的氧化还原性能,是C 3H 6-SCR反应的主要活性位。随着n Cu/n Al的增加,孤立的Cu 2+离子会在分子筛表面迁移、集聚形成CuO物种,从而导致C 3H 6-SCR活性下降。 相似文献
20.
Reaction of YbI 2 with two equivalents of cyclopentylindenyl lithium (C 5H 9C 9H 6Li) affords ytterbium(II) substituted indenyl complex (C 5H 9C 9H 6) 2Yb(THF) 2 (1) which shows high activity to ring-opening polymerization (ROP) of lactones. The reaction between YbI 2 and cyclopentylcyclopentadienyl sodium (C 5H 9C 5H 4Na) gives complex [(C 5H 9C 5H 4) 2Yb(THF)] 2O 2 (2) in the presence of a trace amount of O 2, the molecular structure of which comprises two (C 5H 9C 5H 4) 2Yb(THF) bridged by an asymmetric O 2 unit. The O 2 unit and ytterbium atoms define a plane that contains a Ci symmetry center. 相似文献
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