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1.
The purpose of this study was to calculate the structures and energetics of CH3OH$_{2}^{+}$(H2O)n and CH3SH$_{2}^{+}$(H2O)n in the gas phase: we asked how the CH3OH$_{2}^{+}$ and CH3SH$_{2}^{+}$ moieties of CH3OH$_{2}^{+}$(H2O)n and CH3SH$_{2}^{+}$(H2O)n change with an increase in n and how can we reproduce the experimental values ΔH°n−1,n. For this purpose, we carried out full geometry optimizations with MP2/6‐31+G(d,p) for CH3OH$_{2}^{+}$(H2O)n (n=0,1,2,3,4,5) and CH3SH$_{2}^{+}$(H2O)n (n=0,1,2,3,4). We also performed a vibrational analysis for all clusters in the optimized structures to confirm that all vibrational frequencies are real. All of the vibrational frequencies of these clusters are real, and they correspond to equilibrium structures. For CH3OH$_{2}^{+}$(H2O)n, when n increases, (1) the C O bond length decreases, (2) the C H bond lengths do not change, (3) the O H bond lengths increase, (4) the OCH bond angles increase, (5) the COH bond angles decrease, (6) the charge on CH3 becomes less positive, and (7) these predicted values, except for the O H bond lengths of CH3OH$_{2}^{+}$(H2O)n, approach the corresponding values in CH3OH. The C O bond length in CH3OH$_{2}^{+}$(H2O)5 is shorter than that in CH3OH$_{2}^{+}$ in the gas phase by 0.061 Å at the MP2/6‐31+G(d,p) level. Except for the S H bond lengths in CH3SH$_{2}^{+}$(H2O)n, however, the structure of the CH3SH$_{2}^{+}$ moiety does not change with an increase in n. © 2000 John Wiley & Sons, Inc. J Comput Chem 22: 125–131, 2001  相似文献   

2.
The auxiliary functions $Q_{nn'}^{q}(p,pt)$ and $G_{-nn'}^{q}(p_{a},p,pt)$ which are used in our previous paper [Guseinov, I. I.; Mamedov, B. A. Int J Quantum Chem 2001, 81, 117] for the computation of multicenter electron‐repulsion integrals over Slater‐type orbitals (STOs) are discussed in detail, and the method is given for their numerical computation. The present method is suitable for all values of the parameters pa, p, and pt. Three‐ and four‐center electron‐repulsion integrals are calculated for extremely large quantum numbers using relations for auxiliary functions obtained in this paper. © 2001 John Wiley & Sons, Inc. Int J Quantum Chem, 2001  相似文献   

3.
Hybrid density functional theory calculations on the structures, vibrational frequencies, electron binding and dissociation energies, and bonding properties of CuO$_{3}^{-}$ and CuO3 species have been carried out. Stable isomers containing an O3 subunit and composed of O2 bound to CuO have been located on the potential energy hypersurfaces of CuO$_{3}^{-}$ and CuO3. The isomers formed by O2 bonded to CuO in side‐on and end‐on coordination are more stable than those containing an O3 subunit. © 2001 John Wiley & Sons, Inc. Int J Quant Chem 81: 162–168, 2001  相似文献   

4.
The γ-distonic radical ions R$ \mathop {\rm O}\limits^ + $CHR′CH2?HR″ and their molecular ion counterparts R$ \mathop {\rm O}\limits^{{\rm + } \cdot } $CHR′CH2CH2R″ have been studied by isotopic labelling and collision-induced dissociation, applying a potential to the collision cell in order to separate activated from spontaneous decompositions. The stability of CH3$ \mathop {\rm O}\limits^ + $HCH(CH3)CH2?HCH3, C2H5$ \mathop {\rm O}\limits^ + $HCH(CH3)CH2?HCH3, CH3$ \mathop {\rm O}\limits^ + $HCH(CH3)CH2?H2, CH3$ \mathop {\rm O}\limits^ + $HCH2CH2?HCH3 and C2H5$ \mathop {\rm O}\limits^ + $HCH2CH2?HCH3, has been demonstrated and their characteristic decomposition, alcohol loss, identified. For all these γ-distonic ions, the 1,4-H abstraction leading to their molecular ion counterpart exhibits a primary isotope effect.  相似文献   

5.
Characterization of [C4H5O]+ ions in the gas phase using their collisional activation spectra shows that the four C3H5\documentclass{article}\pagestyle{empty}\begin{document} $\mathop {\rm C}\limits^ + =\!= $\end{document}O isomers CH2?C(CH3)\documentclass{article}\pagestyle{empty}\begin{document} $\mathop {\rm C}\limits^ + =\!= $\end{document}O, CH2?CHCH2\documentclass{article}\pagestyle{empty}\begin{document} $\mathop {\rm C}\limits^ + =\!= $\end{document}O, CH3CH?CH\documentclass{article}\pagestyle{empty}\begin{document} $\mathop {\rm C}\limits^ + =\!= $\end{document}O and ?? \documentclass{article}\pagestyle{empty}\begin{document} $\mathop {\rm C}\limits^ + =\!= $\end{document}O are stable for ≥ 10?5 s. It is concluded further from the characteristic shapes for the unimolecular loss of CO from C3H5\documentclass{article}\pagestyle{empty}\begin{document} $\mathop {\rm C}\limits^ + =\!= $\end{document}O ions generated from a series of precursor molecules that the CH2?CH(CH3)\documentclass{article}\pagestyle{empty}\begin{document} $\mathop {\rm C}\limits^ + =\!= $\end{document}O- and CH2?CHCH2\documentclass{article}\pagestyle{empty}\begin{document} $\mathop {\rm C}\limits^ + =\!= $\end{document}O-type ions dissociate over different potential surfaces to yield [allyl]+ and [2-propenyl]+ [C3H5]+ product ions respectively. Cyclopropyl carbonyl-type ions lose CO with a large kinetic energy release, which points to ring opening in the transition state, whereas this loss from CH3CH?CH\documentclass{article}\pagestyle{empty}\begin{document} $\mathop {\rm C}\limits^ + =\!= $\end{document}O-type ions is proposed to occur via a rate determining 1,2-H shift to yield 2-propenyl cations.  相似文献   

6.
The charge stripping mass spectra of [C2H5O]+ ions permit the clear identification of four distinct species: \documentclass{article}\pagestyle{empty}\begin{document}${\rm CH}_{\rm 3} - {\rm O - }\mathop {\rm C}\limits^{\rm + } {\rm H}_{\rm 2}$\end{document}, \documentclass{article}\pagestyle{empty}\begin{document}${\rm CH}_{\rm 3} - \mathop {\rm C}\limits^{\rm + } {\rm H - OH}$\end{document}, and \documentclass{article}\pagestyle{empty}\begin{document}${\rm CH}_{\rm 2} = {\rm CH - }\mathop {\rm O}\limits^{\rm + } {\rm H}_{\rm 2}$\end{document}. The latter, the vinyloxonium ion, has not been identified before. It is generated from ionized n-butanol and 1,3-propanediol. Its heat of formation is estimated to be 623±12 kJ mol?1. The charge stripping method is more sensitive to these ion structures than conventional collisional activation, which focuses attention on singly charged fragment ions.  相似文献   

7.
Several \documentclass{article}\pagestyle{empty}\begin{document}$ \left[{{\rm C}_{{\rm 4}} {\rm H}_{{\rm\ 8}} } \right]_{}^{_.^ + } $\end{document} ion isomers yield characteristic and distinguishable collisional activation spectra: \documentclass{article}\pagestyle{empty}\begin{document}$ \left[{{\rm 1-butene} } \right]_{}^{_.^ + } $\end{document} and/or \documentclass{article}\pagestyle{empty}\begin{document}$ \left[{{\rm 2-butene} } \right]_{}^{_.^ + } $\end{document} (a-b), \documentclass{article}\pagestyle{empty}\begin{document}$ \left[{{\rm isobutene} } \right]_{}^{_.^ + } $\end{document} (c) and [cyclobutane]+ (e), while the collisional activation spectrum of \documentclass{article}\pagestyle{empty}\begin{document}$ \left[{{\rm methylcyclopropane} } \right]_{}^{_.^ + } $\end{document} (d) could also arise from a combination of a-b and c. Although ready isomerization may occur for \documentclass{article}\pagestyle{empty}\begin{document}$ \left[{{\rm C}_{{\rm 4}} {\rm H}_{{\rm 8}} } \right]_{}^{_.^ + } $\end{document} ions of higher internal energy, such as d or ea, b, and/or c, the isomeric product ions identified from many precursors are consistent with previously postulated rearrangement mechanisms. 1,4-Eliminations of HX occur in 1-alkanols and, in part, 1-buthanethiol and 1-bromobutane. The collisional activation data are consistent with a substantial proportion of 1,3-elimination in 1- and 2-chlorobutane, although 1,2-elimination may also occur in the latter, and the formation of the methylcycloprpane ion from n-butyl vinyl ether and from n-butyl formate. Surprisingly, cyclohexane yields the \documentclass{article}\pagestyle{empty}\begin{document}$ \left[{{\rm linear butene} } \right]_{}^{_.^ + } $\end{document} ions a-b, not \documentclass{article}\pagestyle{empty}\begin{document}$ \left[{{\rm cyclobutane} } \right]_{}^{_.^ + } $\end{document}, e.  相似文献   

8.
The reactions of metastable $ {\rm CH}_{\rm 2} = {\rm CHCH =}\mathop {{\rm OCH}_{\rm 3}}\limits^{\rm +} $ oxonium ions generated by alkyl radical loss from ionized allylic alkenyl methyl ethers are reported and discussed. Three main reactions occur, corresponding to expulsion of H2O, C2H4/CO and CH2O. There is also a very minor amount of C3H6 elimination. The mechanisms of these processes have been probed by 2H- and 13C-labelling experiments. Special attention is given to the influence of isotope effects on the kinetic energy release accompanying loss of formaldehyde from 2H-labelled analogues of $ {\rm CH}_{\rm 2} = {\rm CHCH =}\mathop {{\rm OCH}_{\rm 3}}\limits^{\rm + } $. Suggestions for interpreting these reactions in terms of routes involving ion–neutral complexes are put forward.  相似文献   

9.
Ion cyclotron resonance spectrometry and deuterium labeling have been used to determine that nondecomposing \documentclass{article}\pagestyle{empty}\begin{document}${\rm (CH}_{\rm 3} {\rm)}_{\rm 2} \mathop {\rm N}\limits^{\rm + } {\rm = CH}_{\rm 2}$\end{document} ions do not isomerize to \documentclass{article}\pagestyle{empty}\begin{document}${\rm CH}_{\rm 3} {\rm CH = }\mathop {\rm N}\limits^{\rm + } {\rm HCH}_{\rm 3}$\end{document}.  相似文献   

10.
The electrophilic additions of hydroperoxyl (HO$_{2}^{\mbox{\mathversion{bold}$\cdot$}}$) and alkylperoxyl (RO$_{2}^{\mbox{\mathversion{bold}$\cdot$}}$) radicals to substituted ethenes were studied using the AM1 semiempirical molecular orbital (MO) methods at the self‐consistent field/unrestricted Hartree–Fock (SCF/UHF) level. Reactantlike transition states were predicted for the title additions. The reactivity of an alkylperoxyl radical toward ethenes was found to be decreased as the degree of methyl (Me) substitution on the alkyl group of the radical increased. The relative reactivity and regioselectivity in HO$_{2}^{\mbox{\mathversion{bold}$\cdot$}}$ additions to substituted ethenes was suggested to be SOMO (singly occupied)‐HOMO controlled. A good correlation was established between the activation enthalpy $(\Delta H_{f}^{\ast})$ for the studied additions and the Taft polar substituent constants (σ*) of RO$_{2}^{\mbox{\mathversion{bold}$\cdot$}}$. The Evans–Polanyi correlation between $\Delta H^{\mbox{\mathversion{bold}$\cdot$}}_{f}$ and $\Delta H^{\circ}_{r}$ was justified and the validity of the Hammond postulate was indicated. The calculated results were compared with the available experimental data. © 2000 John Wiley & Sons, Inc. Int J Quant Chem 77: 761–771, 2000  相似文献   

11.
The Generator Coordinate Approximation, a relatively recent approximation formulated to solve systems of three or more bodies, is tested for its accuracy and viability by applying it to calculate the ro‐vibrational energies of the triatomic system H$_{3}^{+}$. We employ in this work a recently formulated basis called the Numerically Generated‐Discrete Variable Representation for the wave function and test it against the well‐known Finite Element Method basis. Comparison of the two results and with other results shows a tentative superiority of the Numerically Generated‐Discrete Variable Representation. In addition, many new physical properties of the Generator Coordinate Approximation were discovered. © 2001 John Wiley & Sons, Inc. J Comput Chem 22: 2028–2039, 2001  相似文献   

12.
Loss of an alkyl group X? from acetylenic alcohols HC?C? CX(OH)(CH3) and gas phase protonation of HC?C? CO? CH3 are both shown to yield stable HC?C? \documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {\rm C}\limits^{\rm + } $\end{document}(OH)(CH3) ions. Ions of this structure are unique among all other [C4H5O]+ isomers by having m/z 43 [C2H3O]+ as base peak in both the metastable ion and collisional activation spectra. It is concluded that the composite metastable peak for formation of m/z 43 corresponds to two distinct reaction profiles which lead to the same product ion, CH3\documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {\rm C}\limits^{\rm + } $\end{document}?O, and neutral, HC?CH. It is further shown that the [C4H5O]+ ions from related alcohols (like HC?C? CH(OH)(CH3)) which have an α-H atom available for isomerization into energy rich allenyl type molecular ions, consist of a second stable structure, H2C?\documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {\rm C}\limits^{\rm + } $\end{document}? C(OH)?CH2.  相似文献   

13.
Tetrazole (H2CN4) and tetrazolate anion (HCN$_{4}^{-}$) are high‐energy compounds with a five‐membered ring‐type structures, which can be easily synthesized by HCN and HN3 and by HCN and N$_{3}^{-}$, respectively, in an irreversible reaction. The ab initio methods including MP2/6‐31G**, B3LYP/6‐31G**, B3LYP/6‐311+G(2d,p), and CBS/QB3 from Gaussian 98 program are employed to study the thermochemistry and reaction mechanism. The transition states of both HCN + HN3 → H2CN4 and HCN + N$_{3}^{-}$ → HCN$_{4}^{-}$ reaction are investigated, and it is found that the latter reaction is more favored than the former one in view of the chemical kinetics and thermodynamics, thus indicating that tetrazole (H2CN4) and tetrazolate anion (HCN$_{4}^{-}$) are formed more easily in an alkali environment than in other systems. Pentazole (HN5) is an unknown high‐energy compound and has not yet been synthesized. For comparison, HN5 and N$_{5}^{-}$, both which have similar type of synthetic reactions to the above‐mentioned reactions, are studied. © 2000 John Wiley & Sons, Inc. Int J Quant Chem 80: 27–37, 2000  相似文献   

14.
A New Mixed Valence Strontium Niobium Oxide Sr7Nb24+Nb45+O21 \documentclass{article}\pagestyle{empty}\begin{document}$ \widehat = $\end{document} Sr1.167NbO3.5 The unknown compound Sr7Nb6O21 kristallisiert nach Einkristall-Röntgenbeugungsdaten rhomboedrisch (Raumgruppe C? R3 ; a = 16,450(5) Å, α = 19,85(1)° trigonale Aufstellung: a = 5,670(1), c = 48,364(13) Å). The compound is built up by perovskite blocks with a width of 6 octahedra. The crystal chemistry especially of the interspace between those blocks is discussed in respect to related compounds.  相似文献   

15.
The relativistic dynamics of one spin‐½ particle moving in a uniform magnetic field is described by the Hamiltonian $\mathbf{h}^{0}_{D}(\pi)=c\alpha\cdot\pi+\beta mc^{2}$. The discrete (and semidiscrete) eigenvalues and the corresponding eigenspinors are in principle known from the work of Dirac, Rabi, and Bloch. These are extensively reviewed here. Next, exact solutions are worked out for the recoil dynamics in relative coordinates, which involves the Hamiltonian $\mathbf{h}^{0}_{D}(-\mathbf{k})=-c\alpha\cdot\mathbf{k}+\beta mc^{2}$. Exact solutions are also explicitly calculated in the case where the spin‐½ particle has an anomalous magnetic moment such that its Hamiltonian is given by $\mathbf{h}_{D}(\pi)=\mathbf{h}^{0}_{D}(\pi)-\beta\mu_{\mathrm{ano}}\sigma\cdot\mathbf{B}$. Similar exact solutions are derived here when the recoiling particle has an anomalous magnetic moment, that is, the eigenvalues and eigenspinors of the Hamiltonian $\mathbf{h}_{D}(-\mathbf{k})=\mathbf{h}^{0}_{D}(-\mathbf{k})-\beta\mu_{\mathrm{ano}}\sigma\cdot\mathbf{B}$ are explicitly obtained. The diagonalized and separable form of the Hamiltonian h D(π), written as $\tilde{\mathbf{h}}_{D}(\pi)$, has exceedingly simple forms of eigenspinors. Similarly, the diagonalized and separable form of the operator h D(? k ), written as $\tilde{\mathbf{h}}_{D}(-\mathbf{k})$, has very simple eigenspinors. The importance of these exact solutions is that the eigenspinors can be used as bases in a calculation involving many spin‐½ particles placed in a uniform magnetic field. © 2001 John Wiley & Sons, Inc. Int J Quant Chem 82: 209–217, 2001  相似文献   

16.
The radical cation and the radical anion of ‘syn’-cyclobuta[1,2-c:3,4-c′]di-1,6-methano[10]annulene (‘syn’-4a,12a:6a, 10a-bishomobinaphthylene; 3 ) have been characterized by their hyperfine data. The highly resolved ESR spectrum of $ 3^{+ \atop \dot{}} $ is dominated by a triplet splitting from the outer pair of methano β-protons (Ho). In contrast, the ESR spectrum of $ 3^{- \atop \dot{}} $ is poorly resolved with the largest coupling constants arising from perimeter α-protons. The different hyperfine features of $ 3^{+ \atop \dot{}} $ and $ 3^{- \atop \dot{}} $ are rationalized by MO models. The SOMO of $ 3^{+ \atop \dot{}} $ ψSA(b1), has substantial LCAO coefficients of the same sign at the bridged atoms C(1), C(6), C(11), and C(16), whereas in the SOMO of $ 3^{- \atop \dot{}} $, ψSS(a1), the four atoms lie in the vertical nodal planes. The large width and the reluctance to saturation of the lines in the ESR spectrum of $ 3^{- \atop \dot{}} $ are attributed to the near-degeneracy of the lowest antibonding MO's. Due to their similar nodal properties, the SOMO's of $ 3^{- \atop \dot{}} $ and the radical anions of binaphthylene ( 4 ), 1,6-methano[10]annulene ( 1 ), and naphthalene ( 2 ) are interrelated. Moreover, because the cyclic π-systems in 3 and 1 deviate in the same way from planarity, the effect of such distortions on the coupling constants, a, of the perimeter α-protons in $ 3^{- \atop \dot{}} $ and $ 1^{- \atop \dot{}} $ should be comparable. Indeed, on going from $ 4^{- \atop \dot{}} $ to $ 3^{- \atop \dot{}} $, the |a| values are reduced exactaly by half as much as the corresponding values on passing from $ 2^{- \atop \dot{}} $ to $ 3^{- \atop \dot{}} $, of which the cyclic π-systems are twice contained in $ 4^{- \atop \dot{}} $ and $ 3^{- \atop \dot{}} $ respectively.  相似文献   

17.
Appearance potentials for the [C7H8]\documentclass{article}\pagestyle{empty}\begin{document}$\mathop +\limits_.$\end{document}ion produced in the fragmentation of n-butyl benzene, iso-butyl benzene and n-pentyl benzene have been measured by photon impact. The results indicate that, at threshold, the fragment ion has the toluene molecular ion structure.  相似文献   

18.
Two theoretical models, a reorganization model and an activation model, are presented for accurately determining the energy barrier of the type M(H2O) of the transition‐metal complexes in the electron‐transfer process. Ab initio calculations are carried out at UMP2/6‐311G level for several redox pairs M(H2O) (M=V, Cr, Mn, Fe, and Co) to calculate their inner‐sphere reorganization energies and activation energies according to the models presented in this article. The values of theoretical inner‐sphere reorganization energies and activational energies are comparable with the experimental results obtained from the vibration spectroscopic data. The theoretical reorganization energy of the every redox pair is four times as much as its activation energy, which agrees with Marcus' electron‐transfer theory. The fact proved that the theoretical models presented in this article are scientific and available for studying the electron‐transfer process of the transition‐metal complex. ©1999 John Wiley & Sons, Inc. Int J Quant Chem 75: 119–126, 1999  相似文献   

19.
\documentclass{article}\pagestyle{empty}\begin{document}$ \left[{{\rm C}_{{\rm 10}} {\rm H}_{{\rm 14}} } \right]_{}^{_.^ + } $\end{document} ions have been generated from a number of adamantanoid compounds, both by ionization and ionization followed-by fragmentation. Metastable ion abundance ratios of competitive reactions indicate the decomposition of these ions from common structures in all cases.  相似文献   

20.
2M(NCS)2M′(SCN)2〈 and [ML6][M′(SCN)4], (M = Co(II) and Ni(II), M′ = Zn(II), Cd(II) and Hg(II) and L = aniline(ani), p-toluidine(tol), pyridine(py), nicotinamide(nia), 2,2′-bipyridine(bipy) and 4-aminopyridine (apy)) have been prepared and characterized. Their structure have been proposed on the basis of molar conductance, magnetic moment, group theoretical calculations, ligand field parameters, infrared and electronic spectral studies. The proposed structures have also been supported by quantitative values of softness ?\documentclass{article}\pagestyle{empty}\begin{document}$ {\rm E}_{\rm n}^{_ + ^ +},{\rm E}_{\rm m}^{_{\rm +}^{\rm +}} $\end{document}”?,. Total softness of M and M′ and their difference \documentclass{article}\pagestyle{empty}\begin{document}$ \Delta {\rm TE}_{\rm n}^{_ + ^ +} \left({{\rm M} - {\rm M}'} \right) $\end{document} have also been derived by the following equations and related to the structure of the complexes. .  相似文献   

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