共查询到20条相似文献,搜索用时 203 毫秒
1.
CpCo(CO) 2 is oxidised by [Cp 2Fe]BF 4 (Cp = C 5H 5) in the presence of neutral ligands L to give the dications [CpCoL 3] 2+ (L = SMe 2, S(n-C 4H 9) 2, PMe 3, C 5H 5N, MeCN; Me = CH 3). In [CpCo(SMe 2) 3] 2+, sulfane ligands are substituted by neutral ligands L, L---L and L---L---L, to give the complexes [CpCoL 3] 2+ (L = SeMe 2, TeMe 2, PMe 3, P(OMe) 3, AsMe 3, SbMe 3, t-C 4H 9NC, C 5H 5N, MeCN), [Cp-Co(L---L)SMe 2] 2+ (L---L = R 2P(CH 2) nPR 2, n = 1, 2, R = C 6H 5; bipyridine, o-phenanthroline, neocuproin) and [CpCo(L---L---L)] 2+ (L---L---L = RP(CH 2CH 2PR 2) 2, R = C 6H 5). The dications react with iodide resulting in the monocations [CpCoL 2I] + and [CpCo(L---L)I] +. Azacobaltocinium cations [CpCo(C 4R 2H 2N)] + (R = H, CH 3) are obtained by reaction of [CpCo(SMe 2) 3] 2+ with metal pyrrolides. 相似文献
2.
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
3.
Using velocity map ion imaging technique, the photodissociation of n-C 4H 9Br in the wavelength range 231–267 nm was studied. The results and our ab initio calculations indicated that the absorption of n-C 4H 9Br in the investigated region originated from the excitations to the lowest three repulsive states, as assigned as 1A″, 2A′ and 3A′ in C s symmetry. Dissociations occurred on the PES surfaces of the three states, terminating in C 4H 9+Br ( 2P 3/2) or C 4H 9 + Br * ( 2P 1/2) as two channels, and being impacted by an avoided crossing between the PES surfaces of the 2A′ and 3A′ states. The transition dipole to the 1A″ state was perpendicular to the symmetry plane, so perpendicular to the C–Br bond. The transitions to the 3A′ state was polarized parallel to the symmetry plane, and also parallel to the C–Br bond. While the transition dipole to the 2A′ state was in the symmetry plane, but formed an angle of about 53.1° with the C–Br bond. We have also determined the avoided crossing probabilities, which affected the relative fractions of the individual pathways, for the photolysis of n-C 4H 9Br near 234 nm and 267 nm. 相似文献
4.
The coordinatively unsaturated uranium(IV) complex U[N(C 6H 5) 2] 4 has been prepared via the stoichiometric reaction of diphenylamine with [(Me 3Si) 2N] 2
H 2. U[N(C 6H 5) 2] 4 coordinates Lewis bases such as Et 2O, THF, pyridine or (EtO) 3PO, based on electronic absorption spectroscopy and 1H NMR studies. Exchange between U[N(C 6H 5) 2] 4 and U[N(C 6H 5) 2] 4(L), where L is THF or pyridine, is rapid on the NMR time-scale between 307 and 323 K. Measurement of equilibrium constants for L = THF provides Δ H and Δ S values of −60 kJ mol −1 and −1.8 × 10 2 J K −1 mol −1, respectively. U[N(C 6H 5) 2] 4 coordinates and binds (EtO) 3PO much more tightly ( Keq = & > 10 4 M −1) than THF or pyridine with the exchange rate between U[N(C 6H 5) 2] 4 and U[N(C 6H 5) 2] 4[OP(OEt) 3] being close to the NMR time-scale. 相似文献
5.
The pyrolysis mechanism of important intermediate 1-hexene of carbon matrix precursor cyclohexane was studied theoretically. Possible reaction paths were designed based on the potential surface scan and electron structure of the initial C–C bond breaking reactions. Thermodynamic and kinetic parameters of the possible reaction paths were computed by UB3LYP/6-31+G* at different temperature ranges. The results show that 1-hexene pyrolyzes at 873 K. When below 1273 K, the major reaction paths are those that produce C 3H 4, and above 1273 K, the major reaction paths are those that produce C 3H 3 from the viewpoint of thermodynamics. From the viewpoint of kinetics, the major product is C 3H 3, it results from the pyrolysis reaction of 1-hexene cracking bond C 3–C 4 and generating C 3H 5 and C 3H 7 with the activation energy Δ E0≠θ=296.32 kJ/mol. Kinetic results also show that product C 3H 4 accompany simultaneously, which is the side reaction starting from the pyrolysis of 1-hexene forming C 4H 7 and C 2H 5 with the activation energy of 356.73 kJ/mol. When reaching 1473 K, the rate constant of the rate-determining steps of these two reaction paths do not show much difference, which means both the reaction paths exist in the pyrolysis process at the high temperature. The above results are basically in accordance with mass spectrum analysis and far more specific. 相似文献
6.
Liquid crystalline 4-XC 6H 4N=NC 6H 4X-4′ [X = C 4H 9 (1a), C 1OH 21 (1b), OC 4H 9 (1c), OC 8H 17(1d)] can be easily prepared in high yields from the corresponding anilines. In order to study the influence of metals on the thermal properties of these materials, we have obtained adducts [AuCl 3(4-C 4H 9OC 6H 4N=NC 6H 4OC 4H 9-4′)] (2) and [Ag(OC1O 3)L 2] [L = 4-XC 6H 4N=NC 6H 4X-4′; X = OC 4H, (3a), OC 8H 17 (3b)]. The silver adducts show themotropic behaviour. Mercuriation of dialkylazobenzenes 1a-b takes place with [Hg(OAc) 2] and LiCl to give [Hg(R)Cl] [R = C 6H 3(N=NC 6H 4X-4′)-2, X-5; X = C 4H 9 (bpap) (4a), C 10H 21 (dpap) (4b)] while dialkoxyazobenzenes 1c–d require [Hg (OOCCF 3) 2] to obtain [Hg(R)Cl] [R = C 6H 3(N---NC 6H 4X-4′)-2, X-5; X = OC 4H 9 (bxpap) (4c), OC 8H 17 (4d)]. 4a-c react with NaI to give [HgR 2] [R= bpap (5a), dpap (5b), bxpap (5c), oxpap (5d)l. Both chloroaryl-, 4a and 4c, and diaryl-mercurials, 5a and 5c, act readily as transmetailating agents towards [Me 4N] [AuCl 4] in the presence of [Me 4N]Cl to give [Au(η 2-R)Cl 2] [R = bpap (6a), bxpap (6b)]. After reaction of [AuCl 3(tht)] (tht = tetrahydrothiophene) with [Me 4N]Cl and 4b (1:2:1), [Me 4N][Au(dpap)Cl 3] (7) can be isolated. C---H activati bxpap (8b)]. None of the complexes 4–8 shows mesomorphic behaviour. 相似文献
7.
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
8.
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
9.
为分析C 1~C 3正构醛、 醇化合物在质子转移反应飞行时间质谱(PTR-TOF MS)中的产物离子特征, 考察了不同E/N值(E: 电场强度, N: 气体分子数密度)下C 1~C 3正构醛、 醇的产物离子种类和强度的变化. 结果表明, 低分子量正构醇类(甲醇、 乙醇和丙醇)倾向于形成质子化聚合物[ nMH] +及其失水离子[ nMH-H 2O] +, 且随着E/N值升高, 醇类会产生较多裂解碎片和多聚体离子. 低分子量正构醛(甲醛、 乙醛和丙醛)主要产生质子化产物[MH] +和一水合质子化产物[M·H 3O] +, 高E/N值(>125 Td)会抑制甲醛质子化, 也会抑制其加合产物的生成. 乙醛倾向于形成水加合物, 且随着E/N值增高, 质子化乙醛与 一水合质子化乙醛的变化趋势相反. 另外, 丙醛在较高的E/N值下会产生一系列聚合物, 如[MH·C 2H 5] +和[2MH] +. 通过分析C 1~C 3正构醛、 醇的质子转移反应特征及产物离子形成过程, 获得了C 1~C 3正构醛、 醇的特征离子和对应的最佳E/N设置值, 为低分子量醛、 醇的定性分析提供了重要依据. 相似文献
10.
以Ni +与C 3H 8反应作为过渡金属离子与烷烃反应的范例体系,用B 3LYP密度泛函方法计算了[Ni,C 3,H 8] +基态势能面上各驻点的构型、频率和能量,结果表明,该反应的H 2分子消除需经历两个基元步骤,即Ni +首先插入一级或二级C-H键,然后经H转移过渡态异构化为较稳定的中间体,继而解离产生H 2分子.计算的反应热为142.28kJ/mol,与相应的实验值(127.85kJ/mol)符合较好. 相似文献
11.
The complex [MoW(μ-CC 6H 4Me-4)(CO) 2(η 7-C 7H 7)(η 5-C 2B 9H 10Me)] reacts with diazomethane in Et 2O containing EtOH to afford the dimetal compound [MoW(OEt)(μ-CH 2){μ-C(C 6H 4Me-4)C(Me)O}(η 7-C 7H 7)(η 5-C 2B 9H 10Me)]. The structure of this product was established by X-ray diffraction. The Mo---W bond [2.778(4) Å] is bridged by a CH 2 group [μ-C---Mo 2.14(3), μ-C---W 2.02(3) Å] and by a C(C 6H 4Me-4)C(Me)O fragment [Mo---O 2.11(3), W---O 2.18(2), Mo---C(C 6H 4Me-4) 2.41(3), W---C(C 6H 4Me-4) 2.09(3), Mo---C(Me) 2.26(3) Å]. The molybdenum atom is η 7-coordinated by the C 7H 7 ring and the tungsten atom is η 5-coordinated by the open pentagonal face of the nido-icosahedral C 2B 9H 10Me cage. The tungsten atom also carries a terminally bound OEt group [W---O 1.88(3) Å]. The 1H and 13C-{ 1H} NMR data for the dimetal compound are reported and discussed. 相似文献
12.
Spatial structure of six β-substituted enones, with common structure R 1O–CR 2CH–COCF 3, were R 1 = C 2H 5, R 2 = H (ETBO); R 1 = R 2 = CH 3 (TMPO); R 1 = C 2H 5, R 2 = C 6H 5 (ETPO); R 1 = C 2H 5, R 2 = 4- O 2NC 6H 4 (ETNO); R 1 = C 2H 5, R 2 = C(CH 3) 3 (ETDO) were investigated by 1H and 19F NMR, infrared spectroscopy and AM1 calculations. NMR spectra revealed that enones (MBO), (ETBO) and (TMPO) are exclusively (3 E) isomers, whereas in (ETPO), (ETNO) and especially in (ETDO) the percentage of (3 Z) isomers is significant and depends on the nature of solvents. Conformational behaviour of studied enones are determined by the rotation around of CC double bond, C–C and C–O single bonds (correspondingly trifluoroacetyl and alkoxy groups), and ( EZZ) conformer being the most stable in all cases. IR spectra revealed that with the exception of (ETDO) ( EZZ) conformer is most populated in all cases. Bulky substituents like phenyl or tert-butyl group at β-position of enone result in the equilibrium mainly between ( EZZ) and ( ZZZ) forms, whereas β-hydrogen and β-methyl substituents determine the equilibrium between ( EZZ) and ( EEZ) or ( EZE) conformers. 相似文献
13.
以氯化钴、 对叔丁基磺酰杯[4]芳烃(H 4TC4A-SO 2)和非对称性3-(1 H-四唑-5-基)苯甲酸(H 2L)为原料, 通过溶剂热法合成了一个具有四面体配位笼结构的16核化合物[Co 16(TC4A-SO 2) 4(OH) 4(L) 8]·[(C 8H 20N)(C 4H 12N) 2(C 2H 8N)]·solvent(Co 16-TC4A-SO 2). 采用X射线单晶衍射、 X射线粉末衍射、 热重分析、 红外光谱方法对配合物进行了表征. 将Co 16-TC4A-SO 2笼簇直接负载到碳纸上(Co 16-TC4A-SO 2/CP)用作工作电极, 其对析氧反应(OER)展现出较好的催化性能. 在1 mol/L KOH中, Co 16-TC4A-SO 2/CP在343.8 mV的过电位下达到10.0 mA/cm 2电流密度, Tafel斜率为79.31 mV/dec, 并且在20.0 mA/cm 2电流密度下表现出长达48 h的催化稳定性. 相似文献
14.
Ir(H) 2(OR f)P 2 (P = P tBu 2Ph, R f = CH 2CF 3) reacts with ethylene at 25°C to give R fOH, ethane and Ir(P C)P(C 2H 4) (2) then Ir(P C)(C 2H 4) 2 (1) and Ir(P C)H(OR f)P (3) (P C = η 2-C 6H 4P tBu 2). It is shown that 2 and 1 are in equilibrium by P and C 2H 4 addition/dissociation. Compound 3 is a product “late” in the reaction sequence, and results from H---OR f oxidative addition to 2. Since 3 reacts with ethylene to give 2, 2 and 3 are in thermal equilibrium. Compound 3 reacts readily with H 2 to give IrH 5P 2 and R fOH. The reason why OR f and ethylene ligands seem to be mutually incompatible is discussed. 相似文献
15.
CpIr(η 4-C 6H 6) (2) has been obtained in high yield by a four-step synthesis. Thermal reaction of 2 with CpCO(C 2H 4) 2 and photochemical reaction of 2 with CpRh(C 2H 4) 2 or CpRh(C 2H 4) 2 give the compounds μ-(η 3: η 3-C 6H 6)CoIrCp 2 (3), μ-(η 3: η 3-C 6H 6)RhIrCp 2 (4), and μ-(η 3: η 3-C 6H 6)(RhCp)(IrCp) (5), respectively. The X-ray crystallography data of 3 and 4 reveal a boat-shaped conformation of the synfacially bridging benzene ligand with a rather long Co---Ir bond distance in 3 and a relatively short Rh---Ir bond length in 4 which are caused by almost constant folding angles of the benzene unit. The dynamic behaviour of the benzene bridge was investigated by NMR spectrometry. 相似文献
16.
N-等基-N-(2-氰乙基)-二茂铁磺酰胺[C 5H 5FeC 5H 4SO 2N(C 2H 4CN)CH 2C 6H 5]为黄色柱状晶体,属单斜晶系,空间群P2 1/n,晶胞参数为:α=8.750(1),b=12.876(5),c=16.744(2)Å,β=94.75(1)°,V=1880.0Å 3,Z=4,计算密度D calc=1.442g/cm 3。在CAD-4四园衍射仪上,用MoK α射线收集衍射数据,用Patterson函数法和差值Fourior合成求解晶体结构。经以2226个独立衍射点用全矩阵最小二乘修正,最后使偏离因子R=0.0466.分子中S原子、N原子以不等性sp 3杂化与周围原子健合。 相似文献
17.
柚皮素是一种天然黄酮类化合物,几乎不溶于水。利用晶体工程学原理可以有效改善天然产物的溶解性。本文合成了柚皮素和三乙胺的有机盐一水合物[C_(15)H_(11)O_5]-·[C_6H_(16)N]+·H_2O,测定了其晶体结构。解析结果表明,有机盐水合物属于单斜晶系,P2_1/n空间群。柚皮素7取代位的羟基上的质子转移到了三乙胺的N原子上,并形成了N~+—H....O~-氢键。羟基阴离子与4'取代位上的羟基形成了O—H....O~-氢键,产生了一维的氢键链状结构。水分子通过两种氢键作用将一维的氢键链连接成二维的氢键网络。形成三乙胺盐一水合物后,柚皮素在水中的溶解度增加了20倍。 相似文献
18.
Aiming to identify the spiro metallaaromatic systems with potential application value, (C 10H 10M) 2?(M=Ni, Pd, Pt) derivatives were theoretically investigated. (C 10H 10M) 2?-Iso1, which has two 6-membered rings(6MRs) connected by the M spiro atom, is a 14π-aromatic as a whole plane. (C 10H 10M) 2?-Iso2 has one 6π-aromatic 5MR and one 10π-aromatic 7MR connected by the spiro atom. The free (C 10H 10M) 2? dianions could not exist due to their rather high frontier orbital energies, while the neutral (C 10H 10M)Li 2 compounds are extremely stable against dissociation. Since (C 10H 10M)Li 2 coumponds are not fully coordinated, they trend to form (C 10H 10M)Li 42+ dications, or even[(C 10H 10M)Li 2] n polymers. Arguably, (C 10H 10M) 2? planes are not the only examples for spiro metallaaromaticity, their derivatives are also potential material building blocks. 相似文献
19.
The reactions of hydroxyl radical, hydrogen atom and hydrated electron intermediates of water radiolysis with N-isopropylacrylamide (NIPAAm) were studied by pulse radiolysis in dilute aqueous solutions. OH, H and e aq− react with NIPAAm with rate coefficient of (6.9±1.2)×10 9, (6.6±1)×10 9, and (1.0±0.2)×10 10 mol −1 dm 3 s −1. In OH and H radical addition to the double bond mainly -carboxyalkyl type radicals form, (OHCH 2CH √C(N- i-C 3H 7)O and CH 3CH √C(N- i-C 3H 7)O). In reaction of e aq− oxygen atom centered radical anion is produced (CH 2CHC √(N- i-C 3H 7)O −), the anion undergoes reversible protonation with p Ka=8.7. There is also an irreversible protonation on the β-carbon atom that produces the same radical as forms in H atom reaction (CH 3CH √C(N- i-C 3H 7)O). The -carboxyalkyl type radicals at low NIPAAm concentration (0.1–1 mmol dm −3) mainly disappear in self-termination reactions, 2 kt,m=8.4×10 8 mol −1 dm 3 s −1. At higher concentrations the decay curves reflect the competition of the self-termination and radical addition to monomer (propagation). The termination rate coefficient of oligomer radicals containing a few monomer units is 2 kt≈2×10 8 mol −1 dm 3 s 1. 相似文献
20.
Reaction of ansa-cyclopentadienyl pyrrolyl ligand (C 5H 5)CH 2(2-C 4H 3NH) (2) with Ti(NMe 2) 4 affords bis(dimethylamido)titanium complex [(η 5-C 5H 4)CH 2(2-C 4H 3N)]Ti(NMe 2) 2 (3) via amine elimination. A cyclopentadiene ligand with two pendant pyrrolyl arms, a mixture of 1,3- and 1,4-{CH 2(2-C 4H 3NH)} 2C 5H 4 (4), undergoes an analogous reaction with Ti(NMe 2) 4 to give [1,3-{CH 2(2-C 4H 3N)} 2(η 5-C 5H 3)]Ti(NMe 2) (5). Molecular structures of 3 and 5 have been determined by single crystal X-ray diffraction studies. 相似文献
|