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1.
The mechanism of the spin-forbidden reaction Ti+(4F, 3d24s1) + C2H4→TiC2H2 + (2A2) + H2 on both doublet and quartet potential energy surfaces has been investigated at the B3LYP level of theory. Crossing points between the potential energy surfaces and the possible spin inversion process are discussed by means of spin-orbit coupling (SOC) calculations. The strength of the SOC between the low-lying quartet state and the doublet state is 59.3 cm−1 in the intermediate complex IM1-4B2. Thus, the changes of its spin multiplicity may occur from the quartet to the doublet surface to form IM1-2A1, leading to a sig-nificant decrease in the barrier height on the quartet PES. After the insertion intermediate IM2, two distinct reaction paths on the doublet PES have been found, i.e., a stepwise path and a concerted path. The latter is found to be the lowest energy path on the doublet PES to exothermic TiC2H2 +(2A2) + H2 products, with the active barrier of 4.52 kcal/mol. In other words, this reaction proceeds in the following way: Ti++C2H44IC→IM1-4B24,2ISC→IM1-2A1→[2TSins]→IM2→[2TSMCTS]→IM5→TiC2H2 +(2A2)+H2. Supported by ‘Qinglan’ Talent Engineering Funds by Tianshui Normal University.  相似文献   

2.
Gravimetry in combination with X-ray phase analysis, X-ray crystallography, and X-ray densitometry were used to determine the contents of V5+, V4+, and Ti4+ ions and vacancies in solid solutions formed by the reaction of V2O5 with TiO2 in air at atmospheric pressure.  相似文献   

3.
The reaction of [Cp*2RuBr]+Br with bromine in CH2Cl2 (CD2Cl2) in an inert atmosphere at room temperature produces the complexes [Cp*Ru(Br)C5Me4CH2Br]+Br3 (syn conformer), [Cp*Ru(Br)C5Me3(CH2Br)2]+ (syn and anti conformers), and [Ru(Br)(C5Me4CH2Br)2]+ (syn conformer). All complexes were characterized by 1H and 13C NMR spectroscopy; the former complex, by elemental analysis. These complexes were also prepared by the reaction of [Cp*RuC5Me4CH2]+BF4 with bromine in CH2Cl2. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2712–2718, December, 2005.  相似文献   

4.
The potential energy surfaces of the (CH3)nH3?n M+ ions, where n = 1, 2; M = Si, Ge, were scanned using the B3LYP method with 6–31G* and aug-cc-pVDZ basis sets. The major attention was given to isomeric species having the form of complexes of the HM+ and CH3M+ ions with hydrogen, methane, and ethane molecules. These species were characterized previously neither by experimental nor by theoretical methods. It was found that these species become more stable in going from Si to Ge; the complex [CH3Ge+CH4] is the second isomer in the energy after (CH3)2HGe+. However, the heights of the activation barriers to formation of these complexes from the most stable isomer, though decreasing in going from Si to Ge, remain relatively high and, what is particularly important, somewhat exceed the activation barrier to formation of the complex [H3Ge+·C2H4].  相似文献   

5.
Reactions of N-(2-hydroxy-3,5-R1,R2-benzyl)-4-aminoantipyrines with copper acetate in ethanol gave complexes with Schiff bases (SBs) rather than the expected complexes with reduced SBs; i.e., the starting ligands undergo oxidative dehydrogenation during the complexation reaction. The corresponding complexes with reduced SBs were obtained from sodium salts of the ligands and cupric sulfate in aqueous solutions. Kinetic measurements showed that oxidative dehydrogenation occurs in the heteroleptic complexes Cu(L i )(CH3COO)(X) (L i H are derivatives of N-(2-hydroxy-3,5-R1,R2-benzyl)-4-aminoantipyrines; i = 6–10; X = H2O, CH3OH, CH3CH2OH) but does not occur in the complexes CH3OH, CH3CH2OH. The absence of oxidative dehydrogenation of the ligands in Cu(L i )2 · H2O can be explained by the octahedral environment of the Cu2+ ion and, accordingly, the absence of the coordination site for molecular oxygen. The molecular structures of two Cu(II) complexes with SBs were determined by X-ray diffraction.  相似文献   

6.
A new molybdophosphate (NH4)8{Mo2VO4[(Mo2VIO6)CH3C(O)(PO3)2]2}·14H2O (1), has been synthesized by the reaction of {Mo2VO4(H2O)6}2+ fragments with 1-hydroxyethylidenediphosphonate (hedp HOC(CH3)(PO3H2)2), and it is characterized by 31P NMR, IR, UV, element analysis, TG and single-crystal X-ray analysis. The structure analysis reveals that the polyoxoanion can be described as two {(Mo2VIO6)(CH3C(O)(PO3)2} units connected by a {Mo2VO4}2+ moiety. In the structure, the six Mo atoms are arranged into a new “W-shaped” structure, which represents a new kind of molybdophosphate.  相似文献   

7.
The reaction mechanism of the gas-phase PtCH2 + with H2S has been systematically investigated on the doublet and quartet potential energy surfaces at BPW91/6-311++G(2d, p)∪ SDD level. The Pt in PtCH2 + prefers to attack S–H bond in H2S. For PtCH2 + + H2S reaction, the potential energy surfaces (PESs), including three reaction pathways of hydrogen (including one and two hydrogen elimination) and methane elimination, have been explored and characterized. By contrast with hydrogen elimination, methane elimination reaction channel is energetically favorable, which is in good agreement with the experimental observation. The optimal S–H bond activation is the first step, followed by cleavage of Pt–C and Pt–S bond. About the path a and b, the lowering of activation barrier is mainly caused by the more stabilizing transition state interaction \(\varDelta E_{\text{int}}^{ \ne }\), which is the actual interaction energy between the deformed reactants in the transition state.  相似文献   

8.
The crystal and molecular structure of doubly protonated tetraazamacrocyclic complex of gold(III) [Au(C14H24N4)][H3O](ClO4)4 has been determined. The crystals are monoclinic: a = 11.158(2) Å, b = 8.243(1) Å, c = 14.756(2) Å; β = 98.65(1)°, V = 1341.8(3) Å3, Z = 2, ρ(calc) = 1.134 g/cm3, space group P21/n. The structure is built of almost flat centrosymmetrical Au(C14H24N4)]3+ and [H3O]+ cations and [ClO4]? anions. The gold atom is coordinated with four nitrogen atoms of the ligand forming a flat square. The coordinated ligand is protonated at its γ-carbon atoms of the two six-membered chelate rings. The Au-N bond lengths are almost identical (the mean value is 1.994 Å). The six-membered rings of the complex contain C=N diimine bonds. The [H3O]+ oxonium ion has H-bonds with the oxygen atoms of perchlorate ions.  相似文献   

9.
In this paper, we investigated three ligand systems, symmetric and asymmetric pyridyl-containing tridentate ligands (L1NH2 = (bis(2-pyridylmethyl)-amino)-ethylamine, L2H = (bis(2-pyridylmethyl)-amino)-acetic acid, L3NH2 = [(6-amino-hexyl)-pyridyl-2-methyl-amino]-acetic acid) as bifunctional chelating agents for labeling biomolecules. These ligands reacted with the precursor fac-[188Re(CO)3(H2O)3]+ and yielded the radioactive complexes fac-[188Re(CO)3L] (L = three ligands), which were identified by RP-HPLC. The corresponding stable rhenium tricarbonyl complexes (1–3) were allowed for macroscopic identification of the radiochemical compounds. 188Re tricarbonyl complexes, with log P o/w values ranging from −1.36 to −0.32, were obtained with yields of ≥90% using ligand concentrations within the 10−6−10−4M range. Challenge studies with cysteine and histidine revealed the high stability properties of these radioactive complexes, and biodistribution studies in normal mice indicated a fast rate of blood clearance and high rate of total radioactivity excretion, primarily through the renal-urinary pathway. In summary, these asymmetric and symmetric pyridyl-containing tridentate ligands are potent bifunctional chelators for the future biomolecules labeling of fac-[188Re(CO)3(H2O)3]+.  相似文献   

10.
The products resulting from the reaction of TiF4 with Ph2P(O)(CH2)2C(O)Me (L') in CH2Cl2 have been studied by 19F{1H} and 31P{1H} NMR spectroscopy. At a twofold excess of L', solution contains cis-TiF4(L')2 (>90%), trans-TiF4(L')2, and fac-[TiF3L3']+, where L' is coordinated via the P=O group, as well as the dimer [(Ti2F7L'2)2]+, where L' is coordinated through the P=O and C=O groups. An equimolar solution contains dimeric and polynuclear complexes containing moieties with three terminal cis fluorine ions, while the other coordination sites are occupied by the P=O groups and F bridges. At a twofold excess of TiF4, ligand L' coordinates via the P=O and C=O groups and behaves as a bridge along with F ions. Thermodynamic stability of the structures of the TiF4L'2 isomers and the structure of [(µ-F)(µ-L')2(TiF3)2]+ has been calculated.  相似文献   

11.
We report herein a comprehensive study of the gas-phase Fe+-mediated oxidation of ethane by N2O on both the sextet and quartet potential energy surfaces (PESs) using density functional theory. The geometries and energies of all the relevant stationary points are located. Initial oxygen-atom transfer from N2O to iron yields FeO+. Then, ethane oxidation by the nascent oxide involves C–H activation forming the key intermediate of (C2H5)Fe+(OH), which can either undergo C–O coupling to Fe+ + ethanol or experience β-H shift giving the energetically favorable product of FeC2H4 + + H2O. Reaction of FeC2H4 + with another N2O constitutes the third step of the oxidation. N2O coordinates to FeC2H4 + and gets activated by the metal ion to yield (C2H4)Fe+O(N2). After releasing N2 through the direct H abstraction and/or cyclization pathways, the system would be oxidized to ethenol, acetaldehyde, and oxirane, regenerating Fe+. Oxidation to acetaldehyde along the cyclization –C–to–C hydrogen shift pathway is the most energetically favored channel.  相似文献   

12.
13.
Gas-phase infrared photodissociation spectroscopy is reported for the microsolvated [Mn(ClO4)(H2O) n ]+ and [Mn2(ClO4)3(H2O) n ]+ complexes from n = 2 to 5. Electrosprayed ions are isolated in an ion-trap where they are photodissociated. The 2600–3800 cm−1 spectral region associated with the OH stretching mode is scanned with a relatively low-power infrared table-top laser, which is used in combination with a CO2 laser to enhance the photofragmentation yield of these strongly bound ions. Hydrogen bonding is evidenced by a relatively broad band red-shifted from the free OH region. Band assignment based on quantum chemical calculations suggest that there is formation of water—perchlorate hydrogen bond within the first coordination shell of high-spin Mn(II). Although the observed spectral features are also compatible with the formation of structures with double-acceptor water in the second shell, these structures are found relatively high in energy compared with structures with all water directly bound to manganese. Using the highly intense IR beam of the free electron laser CLIO in the 800–1700 cm−1, we were also able to characterize the coordination mode (η2) of perchlorate for two clusters. The comparison of experimental and calculated spectra suggests that the perchlorate Cl—O stretches are unexpectedly underestimated at the B3LYP level, while they are correctly described at the MP2 level allowing for spectral assignment.  相似文献   

14.
The visible light irradiation of the [(η5-C6H7)Fe(η-C6H6)]+ cation (1) in acetonitrile resulted in the substitution of the benzene ligand to form the labile acetonitrile species [(η5-C6H7)Fe(MeCN)3]+ (2). The reaction of 1 with ButNC in MeCN produced the stable isonitrile complex [(η5-C6H7)Fe(ButNC)3]+ (3). The photochemical reaction of cation 1 with pentaphosphaferrocene Cp*Fe(η-cyclo-P5) afforded the triple-decker cation with the bridging pentaphospholyl ligand, [(η5-C6H7)Fe(μ-η:η-cyclo-P5)FeCp*]+ (4). The latter complex was also synthesized by the reaction of cation 2 with Cp*Fe(η-cyclo-P5). The structure of the complex [3]PF6 was established by X-ray diffraction. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2088–2091, November, 2007.  相似文献   

15.
The interactions of carotenoids (bixin, β-carotene and lycopene) with CCl3OO. in aqueous and i-propylalcohol solution saturated with air have been studied by pulse radiolysis. For bixin and β-carotene reaction products from forming process, absorbing in the region of 650 nm, is observed with concomitant carotenoid bleaching (bixin at 500 nm, β-carotene at 450 nm). Their rate constants from forming process are 1.78 ×108 and 7.8 ×107 mol-1 · L · s-1 respectively. However, in the case of lycopene, no such a forming process of reaction as bixin and β-carotene can be observed although there is the bleaching reaction (rate constant 4 ×107 mol-1 · L · s-1). The results suggest that the carotenoid radical cation and an additional radical are produced in the case of bixin and β-carotene, whereas lycopene undergoes electron transfer with CCl3OO., forming cation radical.  相似文献   

16.
The purpose of this work was to indirect label IgG with fac-[188Re(CO)3(H2O)3]+ and to check the radiochemical behavior of the labeled product. The compound of (bis(2-pyridylmethyl)-amino)-acetic acid (L2H) was synthesized and labeled with fac-[188Re(CO)3(H2O)3]+. The labeling yield of 188Re(CO)3–L2H was more than 90%. The effects of protein concentration, reaction time, pH and reaction temperature of labeling of IgG with 188Re(CO)3–L2H were investigated. The conjugation conditions were optimized. The labeled product was analyzed by size exclusion HPLC and TLC. The stability of 188Re(CO)3–L2H–IgG in vitro was high. The results of this study may be useful for [188Re(CO)3(H2O)3]+ labeling of protein for radioimmunotherapy.  相似文献   

17.
The carbocation CH5 + has a unique structure of C s symmetry with three 2-center-2-electron bonds and one 3-center-2-electron bond. This ground-state geometry is different from the prediction by the VSEPR model. We have investigated this carbocation along with related systems, among them, BH5, BLi5, CLi5 +, NH5 2+, NLi5 2+, to seek possible trends and regularities in the variations of their ground-state geometries.  相似文献   

18.
In the Bi2O3-SiO2-V25++O5 system, single crystal solid solutions of the sillenite family of the general composition Bi24(Bi,Si,V)2O40 are obtained by a hydrothermal method and for the first time characterized by neutron and X-ray diffraction analysis. The tetrahedral position is found to contain vanadium ions with different formal charges (V4+ and V5+) responsible for green and orange colors, respectively, of the samples. For the first time, for some sillenites of this system dissymmetrization of the structure (a transition from the I23 space group into P23) is revealed, which is caused by the presence of several atoms in one crystallographic position and also by crystal growth conditions.  相似文献   

19.
The formation and fragmentation energies of the proton and sodium cation complexes with monosubstituted methane, cyclohexane, and benzene derivatives in which carbon atoms are bonded to substituents (NH2, OH, F, Cl, Br, ONO2, NO2, COOH, CN, and Ph) were calculated by the B3LYP/6-31G(d) method. For [M + Na]+ complexes, the formation energies are much lower (and differ from one another to a much lesser extent), while the dissociation energies are much higher, than the corresponding energies of the [M + H]+ complexes. Na+ cation shows a lower selectivity toward localization at functional groups in molecules compared to H+. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 246–249, February, 2008.  相似文献   

20.
The reaction of cyclopentylamine with 2-hydroxy-1-naphthaldehyde and 5-nitrosalicylaldehyde, respectively, in methanol affords two new Schiff bases, 1-(cyclopentyliminomethyl)naphthalen-2-ol (HL1) and 4-nitro-2-(cyclopentyliminomethyl)phenol (HL2). Two new zinc(II) complexes, [Zn(L1)2] (I) and [Zn(L2)2] (II), derived from the Schiff bases, have been prepared and characterized by single-crystal X-ray diffraction, FT-IR, and elemental analysis. Complex I crystallizes in the monoclinic space group P21/c with a = 17.834(4), b = 14.738(3), c = 9.868(2) Å, β = 91.20(3)°, V = 2593.1(9) Å3, Z = 4. Complex II crystallizes in the triclinic space group P \(\bar 1\) with a = 10.206(1), b = 10.502(1), c = 12.554(1) Å, α = 66.771(2)°, β = 78.133(2)°, γ = 76.292(2)°, V = 1191.8(1) Å3, Z = 2. The Zn atom in each complex is coordinated by two N and two O atoms from two Schiff base ligands, forming a tetrahedral geometry. The Schiff bases and the complexes were assayed for antibacterial activities.  相似文献   

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