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1.
The title compound 2,3-dicyclopentadiene-2,3-dimethylbutane (C 5H 5CMe 2CMe 2C 5H 5) 1 shows the typical staggered conformation of a highly substituted ethane derivative with the two largest substituents (C 5H 5) adopting a trans position. The molecule shows C 2 symmetry about the central C–C bond. Due to the high substitution, the central bond of the ethane is elongated to 160.0 pm (X-ray structure analysis) while the DFT calculation finds a value of 159.2 pm. 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.
Distibines of the type R 2SbSbR′ 2 with R = CH 3, R′ = C 2H 5 (1), R = CH 3, R′= n-C 3H 7 (2), R = CH 3, R′= C 6H 5 (3), R = C 2H 5, R′= C 6H 5 (4), R = n-C 3H 7, R′ = C 6H 5 (5), and R = CH 3, R′ = 2,4,6-(CH 3) 2C 6H 2 (6) are formed in equilibria by exchange reactions of the respective distibines of the type R 4Sb 2 and R′ 4Sb 2. 相似文献
4.
Rate coefficients for the reactions of cyclohexadienyl ( c-C 6H 7) radicals with O 2 and NO were measured at 296 ± 2 K. The c-C 6H 7 radicals were detected selectively by laser-induced fluorescence. The rate coefficient for the reaction of c-C 6H 7 with O 2, (4.4 ± 0.5) × 10 −14 cm 3 molecule −1 s −1, was independent of the bath-gas (He) pressure (13–80 Torr). In the reaction of c-C 6H 7 with NO, thermal equilibrium among c-C 6H 7, NO, and C 6H 7NO was observed. The forward and reverse reactions were in the falloff region, and the equilibrium constant was (1.5 ± 0.6) × 10 −15 cm 3 molecule −1. 相似文献
5.
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
6.
Reaction of phosphorus ylides Ph 3PCHC(O)C 6H 4NO 2 (Y′) and ( p-tolyl) 3PCHC(O)C 6H 4Cl (Y″) with HgX 2 (X = Cl, Br and I) in equimolar ratios using methanol as solvent leads to binuclear products. The bridge-splitting reaction of binuclear complex [(Y″) · HgI 2] 2 by DMSO yields the mononuclear complex [(Y″) · HgI 2 · DMSO]. This bridge-splitting reaction can be also a method for the synthesis of mononuclear products. C-coordination of ylides and O-coordination of DMSO are demonstrated by single crystal X-ray analyses of binuclear complexes of [(Y′) · HgI 2] 2 and [(Y″) · HgI 2] 2 and mononuclear complex of [(Y″) · HgI 2 · DMSO]. Characterization of the obtained compounds was also performed by elemental analysis, IR, 1H, 31P, and 13C NMR. Theoretical studies on Hg(II) complexes of Y′ show that the cis-like isomers are about 4–12 kcal/mol less stable than the trans-like structures and the relative energy of cis- and trans-like isomers significantly depends on the size of the bridging halide. These studies on mercury complexes of Y″ show that, formation of mononuclear complexes in DMSO solution in which DMSO acts as a ligand, energetically is more favorable than that of binuclear complexes. 相似文献
7.
The conversion of n-C 4H 10 was undertaken on MoO 3/HZSM-5 catalyst at 773–973 K and the phases of molybdenum species were detected by XRD. The XRD results show that bulk MoO 3 on HZSM-5 can be readily reduced by n-C 4H 10 to MoO 2 at 773 K and MoO 2 can be gradually carburized to molybdenum carbide above 813 K. The molybdenum carbide formed from the carburization of MoO 2 with n-C 4H 10 below 893 K is -MoC 1−x with fcc-structure, while hcp-molybdenum carbide formed above 933 K. During the evolution of MoO 3 to MoO 2 (>773 K) or the carburization of MoO 2 to molybdenum carbide (>813 K), deep oxidation, cracking and coke deposition are serious, in particular at higher reaction temperatures, these lead to the poor selectivity to aromatics. Aromatization of n-C 4H 10 can proceed catalytically on both Mo 2C/HZSM-5 and MoO 2/HZSM-5, the distribution of the products for the two catalysts is similar below 813 K, but the activity for Mo 2C/HZSM-5 is much higher than that for MoO 2/HZSM-5. 相似文献
8.
The photodissociation of n-C 7H 15Br, near the red wing of the absorption A-band, has been investigated utilizing the velocity mapped ion imaging technique. Both the speed and angular distributions of Br *( 2P 1/2) and Br( 2P 3/2) fragments were determined. The experimental data indicate that the photodissociation in the investigated range originates from adiabatic and non-adiabatic transitions of the three low-lying dissociative electronic states. The fragments kinetic energies and the angular distributions show that about 70% energy is deposited into the internal energy of the fragments. These results can be explained using soft impulsive model. The experiment also shows that the anisotropy parameter for Br * is sensitive to the photolysis wavelength. 相似文献
9.
The reduction of colourless [LRe VIIO 3]Br in an acetone-water mixture (6: 1) with zinc amalgam affords green, air-sensitive [LRe VO 2Br] which forms a violet complex [LReO(μ-O) 2ReOBr 2]in aqueous solution (L = 1,4,7-triazacyclononane; C 6H 15N 3). From a similar reduction of [LReO 3]ReO 4 the violet neutral complex [LReO(μ-O) 2ReO(ReO 4) 2] was obtained. [LReO 3] + is deprotonated in alkaline solution (p Ka = 10.3 + 0.2, 25°C) and [(C 6H 14N 3)ReO 3] was isolated as a yellow solid. The latter amido rhenium(VII) compound reacted in dimethylformamide with R---X (R = CH 3, benzyl; X = Cl), affording at the cyclic amine, N,N′,N″-trisalkylated complexes of the type [L′ReO 3]X. The monomeric rhenium(V) complexes [LReOX 2]X (X = Cl, Br, I) were obtained from the reaction of [ n-Butyl 4N]ReOX 4 and L in acetonitrile. IR, UV-vis, 17O NMR spectra of these compounds are reported. 相似文献
10.
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
11.
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
12.
The directed oligomerization of propene and 1-hexene was carried out with a series of Cp′(C 5H 5)ZrCl 2 and Cp 2′ZrCl 2 pre-catalysts (Cp′=C 5HMe 4, C 4Me 4P, C 5Me 5, C 5H 4tBu, C 5H 3-1,3- tBu 2, C 5H 2-1,2,4- tBu 3) together with (C 5H 5) 2ZrCl 2. Oligomers in the molar mass range 300–1500 g/mol for propene and 200–3000 g/mol for 1-hexene were synthesized at 50 °C. The majority of oligomer molecules contain a double-bond end group. Oligomer characterization was carried out by gel permeation chromatography (GPC), 1H and 13C NMR. Vinylidene double bonds (from β-hydrogen elimination) are solely found for the tert-butyl-substituted zirconocenes and for most of the unsymmetrical methyl-substituted Cp′(C 5H 5)ZrCl 2 systems (except Cp′=phospholyl). With (C 4Me 4P)(C 5H 5)ZrCl 2 and with the symmetrical methyl-containing Cp 2′ZrCl 2 pre-catalysts, also vinyl end groups (from β-methyl elimination) are observed in the case of oligopropenes. The vinylidene/vinyl ratio depends on the ligand and the vinyl content increases from C 5HMe 4 (65/35) over C 4Me 4P (61/39) to C 5Me 5 (9/91). The phospholyl zirconocenes and (C 5HMe 4) 2ZrCl 2 also exhibit chain-transfer to aluminum thereby giving saturated oligomers. 相似文献
13.
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
14.
Carbon–hydrogen bond dissociation enthalpies (BDEs) were computed for all haloethenes, C 2H 4−nX n ( n=0–3, X=F, Cl, Br, I), at the B3LYP/6-311+G(3df,2p) level using isodesmic reactions. It was found that C–H bond strengths in the monohaloethenes varied substantially, by as much as 18 kJ mol −1, dependent upon the bond's stereochemical position relative to the halogen. BDEs in the dihaloethanes varied in the order CX 2CH–H>( E)-CHXCX–H>( Z)-CHXCX–H. Trends in the computed bond enthalpies were discussed and explained on the basis of relative steric repulsions and hyperconjugative delocalization interactions, as determined from Natural Bond Orbital analysis. 相似文献
15.
The photodissociation dynamics of the 3s Rydberg state of three ketones (CH 3CO–R, R=C 2H 5, C 3H 7, and iso-C 4H 9) and the ensuing dissociation of the nascent acetyl radical following 195 nm excitation were investigated by ultrafast photoionization spectroscopy. The 3s state the lifetimes of these ketones are similar (2.5–2.9 ps), though lifetimes of the acetyl radical range from 8.6 ps for CH 3CO–C 2H 5, 15 ps for CH 3CO–C 3H 7, to 23 ps for CH 3CO–( iso-C 4H 9), which suggests that for larger R more vibrational degrees of freedom compete for the excess energy so that less energy is partitioned into the internal energy of the acetyl radical. 相似文献
16.
Reactions of the lithium salts of 3-substituted indenes 1, 2 with ZrCl 4(THF) 2 gave two series of nonbridged bis(1-substituted)indenyl zirconocene dichloride complexes. Fractional recrystallization from THF–petroleum ether furnished the pure racemic and mesomeric isomers of [(η 5-C 9H 6-1-C(R 1)(R 2)--- o-C 6H 4---OCH 3) 2ZrCl 2]· nTHF (R 1=R 2=CH 3, n=1, rac-1a and meso-1b; R 1=CH 3, R 2=C 2H 5; n=0.5 or 0, rac-2a and meso-2b), respectively. Complex 1a was further characterized by X-ray diffraction to have a C2 symmetrically racemic structure, where the six-member rings of the indenyl parts are oriented laterally and two o-CH 3O---C 6H 4---C(CH 3) 2--- substituents are oriented to the open side of the metallocene (Ind: bis-lateral, anti; Substituent: bis-central, syn). The four zirconocene complexes are highly symmetrical in solution as characterized by room temperature 1H-NMR, however 1H– 1H NOESY of meso-1b shows that some of the NOE interactions arise from the two separated indenyl parts of the same molecule, which can only be well explained by taking into account the torsion isomers in solution. 相似文献
17.
The cluster [Os 3(CO) 10(MeCN) 2] reacts with indazole (C 7H 6N 2) to give two isomeric products [0s 3( μ-H)( μ-C 7H 5N 2)(CO) 10] in which the five-membered ring has been metallated with N-H cleavage to give an N, N-bonded isomer or with C-H cleavage to give a C, N-bonded isomer. These two isomers have very similar X-ray structures but can be clearly distinguished by 1H NMR methods. They are shown to correspond to related clusters derived from pyrazole. Benzotriazole (C 6H 5N 3) also reacts (as shown earlier by others) to give two isomers: an N, N-bonded species [Os 3( μ-H)( μ-C 6H 4N 3)(CO) 10] coordinated only through the five-membered ring and a minor C, N-bonded isomer [Os 3( μ-H)( μ-C 6H 4N 3)(CO) 10], metallated at the C 6 ring and coordinated through both rings. The former isomer reacts with Me 3NO in acetonitrile to give [Os 3( μ-H)( μ-C 6H 4N 3)(CO) 9(MeCN)] which thermally looses MeCN to produce the coupled product [Os 6( μ-H) 2( μ3-C 6H 4N 3) 2(CO) 18] which was shown by X-ray structure determination to have all six nitrogen atoms coordinated to osmium, a novel situation for coordinated benzotriazole. The two Os 3 units are linked together by an OsNNOsNN ring in a boat conformation with the whole cluster adopting C2 symmetry. 相似文献
18.
We show that thermal desorption kinetics clearly resolve adsorbates bound in different sites on single walled carbon nanotube bundles. The molecules n-C 9H 20 and CCl 4 were compared and it was found that the nanotube internal sites exhibited the highest desorption temperature, whereas external groove sites exhibited the next highest desorption temperature for both molecules. When n-C 9H 20 and CCl 4 coadsorb, the more strongly bound n-C 9H 20 quantitatively displaces CCl 4 from internal sites to groove sites. Molecular shape governs the capacity of the different sites for the two molecules. 相似文献
19.
Reaction of 1,3-thiazolidine-2-thione with tellurium(IV) in hydrobromic acid medium gave the hexabromotellurate, [C 6H 9N 2S 3] 22+[Te IVBr 6] 2− (3). Reaction of 1-methylimidazoline-2-(3H)-thione (L″) with tellurium(IV), in hydrobromic acid medium, gave the mixed-ligand tellurium(II) complex [Te IIL″ 3Br] +Br − (4). The structures of [C 6H 9N 2S 3] 22+[Te IVBr 6] 2− (3) and [Te IIL″ 3Br] +Br − were determined by single crystal X-ray diffraction methods. In 3 the unit cell contains [TeBr 6] 2− anions and two [C 6H 9N 2S 3] + cations. There is no direct bonding between the metal atom and the cations. In the anion only slight angular deviations from the perfect octahedral geometry are observed. The lone pair of electrons on tellurium(IV) is found to be stereochemically inert. In the cation the two five-membered heterocyclic rings adopt different conformations. In complex 4, in the solid state, the planar [Te IIL″ 3Br] + cation and Br − anion are held together by ionic interactions. In the cation, L″ is bonded to the central tellurium atom through the sulphur atom. 相似文献
20.
利用共振增强多光子电离飞行时间质谱(REMPI-TOFMS),研究了长链正一溴代烷烃R_Br(R为正烷烃基)(C 2H5Br,n-C 3H 7Br,n-C 4H 9Br)在234及267nm附近的光解动力学.溴碎片来源于R_Br的直接解离:R_Br→R+Br( 2P 3/2)/Br *(2P1/2).根据测定的离子信号强度,得到了Br *与Br的分支比N(Br *)/N(Br)及相应的相对量子产额(Br *)和(Br).(Br *)与激光波长及分子结构显示了一定的依赖关系.将实验结果用CH3Br的解离模型进行拟合,得到了长链R_Br的光解动力学行为的定性解释. 相似文献
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