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2.
Anion photoelectron spectroscopic experiments and calculations based on density functional theory have been used to investigate and uniquely identify the structural, electronic, and magnetic properties of both neutral and anionic (Rh(m)Co(n)) and (Rh(m)Co(n))(-) (m=1-5, n=1-2) clusters, respectively. Negative ion photoelectron spectra are presented for electron binding energies up to 3.493 eV. The calculated electron affinities and vertical detachment energies are in good agreement with the measured values. Computational results for geometric structures and magnetic moments of both cluster anions and their neutrals are presented. 相似文献
4.
Anionic tetrahydrofuran clusters (THF)(n) (-) (1≤n≤100) are studied with photoelectron imaging as gas-phase precursors for electrons solvated in THF. Photoelectron spectra of clusters up to n=5 show two peaks, one of which is attributed to a solvated open chain radical anion and the other to the closed THF ring. At n=6, the spectra change shape abruptly, which become more characteristic of (THF)(n) (-) clusters containing solvated electrons. From n=6-100, the vertical detachment energies (VDEs) of these solvated electron clusters increase from 1.96 to 2.71 eV, scaling linearly with n(-1/3). For fully deuterated (THF-d8)(n) (-) clusters, the apparent transition to a solvated electron cluster is delayed to n=11. Extrapolation of the VDEs to infinite cluster size yields a value of 3.10 eV for the bulk photoelectric threshold. The relatively large VDEs at onset and small stabilization with increasing cluster size compared to other solvated electron clusters may reflect the tendency of the bulk solvent to form preexisting voids that can readily solvate a free electron. 相似文献
5.
Structural Chemistry - The structures and bonding properties of La(N2)x (x?=?1–8) complexes were investigated by density functional theory (DFT) computations using the B3LYP... 相似文献
6.
The crystal structures of (CNSSS) 2(AsF 6) 2, (CNSSS) 2(SbF6) 2, and two phases of (CNSSS) 2(Sb 2F 11) 2 have been determined. The AsF 6 ?, SbF 6 ?, and α-Sb 2F 11 ? salts crystallize as reddish-brown plates whereas the β-Sb 2F 11 ? salt crystallizes as green rods. The dication ß+SSSNCCNSSS +ß (1 2+) is the same in all four structures and consists of two 7π rings linked by a sp 2-sp 2 C-C bond (1.462 Å in 1 (AsF 6) 2). The packing in the four structures is similar with stacks of dications along the a-axis and alternating sheets of dications and anions lying in the bc-plane. The differences in the dication-dication contacts is reflected in the variable temperature magnetic data. 相似文献
7.
The reaction of AgNO 3 with [(“Bu 4N 2 i-MNT)] 3 in CH 3CN produces a new silver cluster anion [Ag 4( i-MNT) 4] 4? , 3, a species having a tetrahedral arrangement of silver atoms bridged by four i-MNT ligands which has been isolated and characterized by X-ray crystallography as [Bu 4N] 2[(PPh 3) 2] 2 [Ag 4( i-MNT) 4], 4. The reaction of two or three equivalents of Ag(PPh 3) 2NO 3 with [BzEt 3N] 6[Ag 6( i-MNT) 6] in CH 3CN produces two new clusters, [BzEt 3N] 4[Ag 8( i-MNT) 6(PPh 3) 4], 6, and [BzEt 3N] 3[Ag 4( i-MNT) 6(PPh 3) 6], 7, having the common structural feature of an octahedral Ag 6S 12 core. The octanuclear Ag 8 cluster also can be synthesized from the reaction of 4 and PPh 3 in CH 2Ck 2 and compound 5 has been structurally characterized as [Bu 4N] 2[(PPh 3) 2N] 2[Ag 8( i-MNT) 6(PPh 3) 4]. The 31P{ 1H} NMR spectrum of 6 in CD 3CN at ?43° shows two sets of two doublets. The corresponding chemical shift and coupling constant of each species is 9.32 ppm (354, 408.8 Hz) and 9.45 ppm (346.7, 401.7 Hz), respectively. Pertinent crystallographic data are as follows: Compound 4 crystallizes in the orthorhombic space group Cc2a, with a=18.668(3)A, b=36.793(4) A, c=17.836(3)A, Z=4, and V= 12250(3)A 3. Compound 5 crystallizes in the triclinic space group P1, with a=16.506(3)A, b=17.280(3)A, c=19.144(4) A, x=98.485(14)°, β= 105.44(2)°. y=94.63(2), Z= 1, and V = 5164(2)A 3. Compound 6 crystallizes in the monoclinic space group C2/m, with a= 25.341(9)A, b= 25.289(9)A, c= 15.076(7)A, β= 107.19(5)°, Z=2, and V=9230(6)A 3. Compound 7 crystallizes in the monoclinic space group C2/c, with a=25.872(6)A, b=21.288(4) A, c=35,928(5), β=100.98(1)°, Z-4, and V=19426(6)A 3. 相似文献
9.
The first luminescent metal-organic framework (MOF) with [Zn(6)(μ(6)-O)] cluster has been synthesized and realized for reversible sensing of small molecules. 相似文献
10.
The coordination of 10-electron diatomic ligands (BF, CO N 2) to iron complexes Fe(CO) 2(CNAr Tripp2) 2 [Ar Tripp2=2,6-(2,4,6-( iso-propyl) 3C 6H 2) 2C 6H 3] have been realized in experiments very recently ( Science, 2019 , 363, 1203–1205). Herein, the stability, electronic structures, and bonding properties of (E 1E 2)Fe-(CO) 2(CNAr Tripp2) 2 (E 1E 2=BF, CO, N 2, CN −, NO +) were studied using density functional (DFT) calculations. The ground state of all those molecules is singlet and the calculated geometries are in excellent agreement with the experimental values. The natural bond orbital analysis revealed that Fe is negatively charged while E 1 possesses positive charges. By employing the energy decomposition analysis, the bonding nature of the E 2E 1–Fe(CO) 2(CNAr Tripp2) 2 bond was disclosed to be the classic dative bond E 2E 1→Fe(CO) 2(CNAr Tripp2) 2 rather than the electron-sharing double bond. More interestingly, the bonding strength between BF and Fe(CO) 2(CNAr Tripp2) 2 is much stronger than that between CO (or N 2) and Fe(CO) 2(CNAr Tripp2) 2, which is ascribed to the better σ-donation and π back-donations. However, the orbital interactions in CN −→Fe(CO) 2(CNAr Tripp2) 2 and NO +→Fe(CO) 2(CNAr Tripp2) 2 mainly come from σ-donation and π back-donation, respectively. The different contributions from σ donation and π donation for different ligands can be well explained by using the energy levels of E 1E 2 and Fe(CO) 2(CNAr Tripp2) 2 fragments. 相似文献
11.
The electrophoretic behavior of twenty anions has been studied on silica gel-G, titanium (IV) tungstate and silica gel-G- titanium (IV) tungstate admixture layers using 0.1 M solutions of oxalic acid, citric acid, tartaric acid, succinic acid and acetic acid as background electrolyte. The mechanism of migration is explained in terms of adsorption and the solubility of various sodium or potassium salts of the anions in water. Titanium (IV) tungstate behaves only as an adsorbent and not as an ion exchanger. Being a cation exchanger, there is no exchange phenomenon occurring with anions. The migration of halides increase linearly with an increase in the bare ion radii of these ions. Differential migration of the anions on silica gel-G layers led to binary, ternary and quaternary separations of similar anions such as F− – Cl− – Br− – I−, I− – IO3− – IO4−, BrO3− – IO3− and Fe(CN)63− – Fe(CN)64−. The two cyanoferrate ions are separated from industrial waste water and from fixer and bleach solutions. The migration of anions has also been found to be in accordance with their lyotropic numbers. 相似文献
12.
Mononuclear O,O-coordinated complexes K 2(MLCl 2) M = Zn(II), Cd(II) and dinuclear complexes (MZnLCl 2R 2) x along with dinuclear N, N-coordinated complexes (M′ZnH 2LCl 2R 2) y (where M = Zn(II), Cd(II), Hg(II) and M′ = M and Sn(IV); R = Cl, CH 3; x = 0, ?2; y = 0, +2) of N′-1-, N′-2-dihydroxy- N-1-, N-2-dipyridin-2-ylethanedimidamide (H 2L) have been prepared. All complexes have been characterized by 1H NMR, IR, EI-mass spectroscopy and elemental microanalysis. These results are in agreement with our prediction for structures of mono and dinuclear complexes of H 2L and L ?2 with Zn(II) in the gas phase by theoretical studies. 相似文献
13.
An efficient mixed molecular dynamics/quantum mechanics model has been applied to the water cluster system. The use of the MP2 method and correlation consistent basis sets, with appropriate correction for BSSE, allows for the accurate calculation of electronic and free energies for the formation of clusters of 2-10 water molecules. This approach reveals new low energy conformers for (H(2)O)(n=7,9,10). The water heptamer conformers comprise five different structural motifs ranging from a three-dimensional prism to a quasi-planar book structure. A prism-like structure is favored energetically at low temperatures, but a chair-like structure is the global Gibbs free energy minimum past 200 K. The water nonamers exhibit less complexity with all the low energy structures shaped like a prism. The decamer has 30 conformers that are within 2 kcal/mol of the Gibbs free energy minimum structure at 298 K. These structures are categorized into four conformer classes, and a pentagonal prism is the most stable structure from 0 to 320 K. Results can be used as benchmark values for empirical water models and density functionals, and the method can be applied to larger water clusters. 相似文献
14.
SIMS and FAB of solid N 2 generated large N 2n+ clusters (N 4+ -N +54) which showed three types of metastable decay: (i) loss of a single N 2 molecule, assigned to ordinary (“thermal”) metastability, (ii) nearly total disintegration, assigned to radiationless decay of an electronically excited state, and (iii) “magic” losses of very specific small numbers of N 2 molecules, assigned to N 2( v = 1) vibrational relaxation by use of isotope effects. Average N 2 binding energies are estimated. 相似文献
15.
The potential energy curves of some small molecules, H2, N2, O2, F2, HF, CO and NO, in the caged state within C60 cage and in the free state have been calculated by the quantum-chemical method AM1. In this study, the focus is on the cage effect of C60, and the concept of caged state is put forward. The results show that the bond lengths in the caged states are not much different from those in their corresponding free states, but the bond intensities in the caged states are much greater than those in their corresponding free states. 相似文献
16.
Low-energy collision induced dissociation has been used to investigate the structure and stability of microsolvated clusters of the prototypical, aprotic multiply charged anion, Pt(CN)(4)(2-), i.e. Pt(CN)(4)(2-)·(H(2)O)(n) n = 1-4, Pt(CN)(4)(2-)·(MeCN)(m) m =1, 2, and Pt(CN)(4)(2-)·(H(2)O)(3)·MeCN. For all of the systems studied, the lowest energy fragmentation pathway was found to correspond to decay of the cluster with loss of the entire solvent ensemble. No sequential solvent evaporation was observed. These observations suggest that the Pt(CN)(4)(2-) solvent clusters studied here form hydrogen-bonded "surface solvated" structures. Electronic structure calculations are presented to support the experimental results. In addition, the detailed fragmentation patterns observed are interpreted with reference to the differential solvation of the ionic fragmentation and electron detachment potential energy surfaces of the core Pt(CN)(4)(2-) dianion. The results described represent some of the first experiments to probe the microsolvation of this important class of multiply charged anions. 相似文献
17.
The mechanisms of gold(Ⅰ)-catalyzed cycloaddition of 1-(1-alkynyl) cyclopropyl ketones with nucleophiles have been investigated using density functional theory calculations at the B3LYP/6-31G(d,p) level of theory.A polarizable continuum model(PCM) has been established in order to evaluate the effects of solvents on the reactions.The results of the calculations indicate that the first step of the catalytic cycle is the cyclization of the carbonyl oxygen onto the triple bond which forms a new and stable resonance structure of an oxonium ion and a carbocation intermediate.The subsequent ring expansion step results in the formation of the final product and regeneration of the catalyst.Furthermore,the regioselectivity and effect of substituents has been discussed,including an analysis of energy,bond length,and natural bond orbital(NBO) charge distributions in the rate-determining step.Our computational results are consistent with earlier experimental observations. 相似文献
18.
Russian Journal of General Chemistry - 相似文献
19.
Single-crystal X-ray structures of Λ- β 1-[Co( R, R-picchxn)( R-phe)]Br 2, Λ- β 1-[Co( R, R-picchxn)( R-phe)]Br 2·3H 2O and Λ- β 1-[Co( R, R-picchxn)( R-phe)]I 2 are reported. In each structure there are three formula units in the asymmetric unit. Considerable disorder attends the anions and water molecules of crystallisation. In every case the conformer adopted by the coordinated aminoacidate is such that the phenylalaninato side chain is extended in order to minimize non-bonded steric interactions with the Co(tetradentate)fragment. Such an arrangement is in accord with the fact that this kind of diastereoisomer does not participate in any strong intramolecular π- π or NH- π interaction. 相似文献
20.
The preparation of 1,4-phenylene-bis[1-(alkoxycarbonyl)alkylamino-methanephosphonous acids] by the addition of hypophosphorous acid to terephthalylidene-bis[1-(alkoxycar bonyl)alkylamines] is described. Despite expectations, no chiral assistance of the amino acid ester moiety is observed. 相似文献
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