Anisotropic dipole polarizability of transition metal atoms: Sc(2D), Ti(3F,3P), V(4F,4P,6D), Ni(3F) and ions: Sc2+(2D), Ti2+(3F,3P)

Dipole polarizability tensor components and quadrupole moments of transition-metal atoms Sc, Ti, V, Ni, and Cu and ions Sc2+ and Ti2+ are computed using finite field complete active space self-consistent field and multireference configuration interaction ab initio methods. Perpendicular components of the dipole polarizability tensor are calculated from equations involving only parallel components of the polarizability tensor and its average value. Mean polarizability and polarizability anisotropy decrease in the Sc-Ni series. Relativistic effects are accounted for with the Douglas-Kroll Hamiltonian. The consequences of the anisotropic properties of these atoms to their interactions with spherically symmetric rare gases are also discussed.     

Mechanistic insight into the gas-phase reactions of methylamine with ground state Co+(3F) and Ni+(2D)

The gas-phase reaction mechanisms of methylamine (MA) with the ground-state Co(+)((3)F) and Ni(+)((2)D) are theoretically investigated using density functional theory at both the B3LYP/6-311++G(d,p) and B3LYP/6-311++G(3df,2p) levels. The reactions for hydride abstraction and dehydrogenation are analyzed in terms of the topology of potential energy surfaces (PESs). Co(+) and Ni(+) perform similar roles along the isomerization processes to the final products. Hydride abstraction takes place via the key species of metal cation-methyl-H intermediate, followed by a charge transfer process before the direct dissociation of CH(2)NH(2)(+)···MH (M = Co, Ni). The enthalpies of reaction, stability of metal cation-methyl-H species, and competition between different channels account for the sequence of the hydride abstraction products: CoH < NiH < CuH. The most competitive dehydrogenation route occurs through a stepwise reaction, consisting of initial C-H activation, amino-H shift, and direct dissociation of the precursor CH(2)NHM(+)···H(2). This theoretical work sheds new light on the experimental observations and provides fundamental understanding of the reaction mechanisms of amine prototype with late first-row transition metal cations.     

Reactions of Cu+(1S, 3D) with CH3Cl, CH2ClF, CHClF2, and CClF3

The reactions of gas-phase Cu+(1S) and Cu+(3D) with CH3Cl, CH2ClF, CHClF2, and CClF3 are examined using the drift cell technique at 3.5 Torr. State-specific product channels and overall bimolecular rate constants for depletion of the two Cu+ states are determined using electronic state chromatography. Cu+(1S) participates exclusively in association with all four neutrals, whereas Cl abstraction is the dominant product channel for Cu+(3D). The resulting CuCl+ product subsequently abstracts Cl- in a secondary process. Tertiary reactions are also observed, which include both hydride abstraction (with CH3Cl) and fluoride abstraction (with the fluorinated neutrals). All product channels can be understood in terms of the known thermochemical and quantum mechanical (i.e., spin) requirements. Cu+(1S) is depleted by all four neutrals at 30% to 40% of the ADO rate under these conditions, whereas Cu+(3D) is observed to react at approximately 80% of the ADO rate with CH3Cl, CH2ClF, and CHClF2. Reaction of excited state Cu+ with CClF3 occurs at only 7% of the ADO rate. The behavior of Cu+(3D) is consistent with a mechanism in which formation of CuCl+ occurs exclusively on the triplet surface via a mechanism in which the metal ion must interact exclusively with Cl.     

Alignment of atoms following photoionisation: Cd+(4d −1 2 D 5/2,2 D 3/2) and Zn+(3d −1 2 D 3/2)

The linear polarisation of fluorescence radiation following the photoionisation in the 4d _5/2 and 4d _3/2 subshells of Cd and in the 3d _3/2 subshell of Zn has been measured in the energy range of primary photons from threshold up to about 40 eV. The experimental values of the linear polarisation found for the fluorescence radiation of Cd⁺(4d ^?1) ions are in essential agreement with theoretical results obtained by an RRPA calculation (Johnson et al.). For the case of Zn⁺(3d ^?1) on the other hand, no theoretical data are presently available. Using the experimental values of linear polarisation of fluorescence radiation the values of the alignment tensorA ₂₀ have been evaluated for the ions Cd⁺(4d ^{?1 2} D _5/2,² D _3/2) and Zn⁺(3d ^{?1 2} D _3/2).     

Dissociative recombination of H+(H2O)3 and D+(D2O)3 water cluster ions with electrons: cross sections and branching ratios

Dissociative recombination (DR) of the water cluster ions H(+)(H(2)O)(3) and D(+)(D(2)O)(3) with electrons has been studied at the heavy-ion storage ring CRYRING (Manne Siegbahn Laboratory, Stockholm University). For the first time, absolute DR cross sections have been measured for H(+)(H(2)O)(3) in the energy range of 0.001-0.8 eV, and relative cross sections have been measured for D(+)(D(2)O)(3) in the energy range of 0.001-1.0 eV. The DR cross sections for H(+)(H(2)O)(3) are larger than previously observed for H(+)(H(2)O)(n) (n=1,2), which is in agreement with the previously observed trend indicating that the DR rate coefficient increases with size of the water cluster ion. Branching ratios have been determined for the dominating product channels. Dissociative recombination of H(+)(H(2)O)(3) mainly results in the formation of 3H(2)O+H (probability of 0.95+/-0.05) and with a possible minor channel resulting in 2H(2)O+OH+H(2) (0.05+/-0.05). The dominating channels for DR of D(+)(D(2)O)(3) are 3D(2)O+D (0.88+/-0.03) and 2D(2)O+OD+D(2) (0.09+/-0.02). The branching ratios are comparable to earlier DR results for H(+)(H(2)O)(2) and D(+)(D(2)O)(2), which gave 2X(2)O+X (X=H,D) with a probability of over 0.9.     

Reaction of SC+(1D,3D) with H2O, NH3, and CH4: a density functional study.

Density Functional Theory has been used to explore quantitative details of the potential energy hypersurface for the insertion reaction of scandium ion into the O-H, N-H, and C-H bond of water, ammonia, and methane molecules leading to H2 elimination. Both singlet and triplet state channels have been considered. On the basis of the obtained results, it is possible to conclude that for the molecules considered the reaction is a spin-forbidden process. Indeed, it starts in the triplet ground state and ends in the singlet state, the change of the spin state probably occurring immediately after the formation of the electrostatic complex intermediate.     

Electric-field-induced g/u mixing of the E0g+(3P2) and D0u+(3P2) ion-pair states of jet-cooled I2 observed using optical triple resonance

Electric-field-induced electronic state g/u mixing of nearly isoenergetic rovibrational levels of the E0g+(3P2) and D0u+(3P2) ion-pair states of I2 has been observed using optical triple resonance combined with resonance ionization. Detectable mixing with applied fields of 1 kV/cm occurs over a range of energy level separations of < or = 0.3 cm(-1).     

多通道反应O(3P)＋CH2F的理论研究

用密度泛函理论研究了氧原子与氟代甲基自由基的反应.反应中出现的所有物种的平衡构型用B3LYP方法在6-311＋＋G（2d, 2p）基组水平上进行了优化，同时对各物种进行了频率分析；在同一理论水平上计算了各反应通道的势能面变化，分析了反应物、中间体、过渡态、产物的振动模式随反应途径的变化关系，阐明了该多通道反应的反应机理.     

The Reactions of 1-Acetothiosemicarbazidc with P(NR_2)_3 PC1_3 and PCI_5

A Series of new heterocyciophosphorus compounds were synthesizec oy cyclocondensa-tion of 1-acetothiosemicarbazide with P(NR2)3. The further reaction of these compounds with P(NR2)3 gave different compounds depending upon different reaction conditions. The 1-acetothiosemicarbazide can also condense with PCl3 and PCl5 similarly, The reaction mechanism, the spectral properties and chemical properties of these products were also studied and discussed.     

Characterization of a shallow-bound 0g+ valence state of I2 using emission from the D 0u+(3P2) and F' 0u+(1D2) ion-pair states populated by amplified spontaneous emission

A range of vibrational levels of the D 0(u)(+)((3)P(2)) and F' 0(u)(+)((1)D(2)) ion-pair states of I(2) is shown to be easily generated by amplified spontaneous emission (ASE) from their more accessible partners, E 0(g)(+)((3)P(2)) and f' 0(g)(+)((1)D(2)), in sufficient concentration for dispersed fluorescence studies of the D 0(u)(+)((3)P(2)) --> 0(g)(+)(bb) and F' 0(u)(+)((1)D(2)) --> 0(g)(+)(bb) transitions to be carried out. T(0) (J = 49) of this shallow-bound 0(g)(+)(bb) valence state is unambiguously determined and an improved R(e) value of 3.952 +/- 0.005 A is obtained from optimizing the fit of the intensities of the vibrational progressions in the 0(g)(+)(bb) state, and T(e) is found to be 27311.3 +/- 2 cm(-1), leading to D(e) = 442.0 +/- 2 cm(-1).     

Photodissociation spectroscopy of Zn+(H2O) and Zn+(D2O)

We report on a study of the photodissociation spectroscopy of weakly bound Zn+(H2O) and Zn+(D2O) complexes. The work is supported by ab initio electronic structure calculations of the ground and low-lying excited energy surfaces. We assign two molecular absorption bands in the near UV correlating to Zn+ (4s-4p)-based transitions, and identify vibrational progressions associated with both intermolecular and intramolecular vibrational modes of the cluster. Partially resolved rotational structure is consistent with a C(2V) equilibrium complex geometry. Experimental spectroscopic constants are in very good agreement with ab initio theoretical predictions. Results are compared with previous work on main group and transition metal ion-H2O clusters.     

Reactions of 1S, 1D,and 3P carbon atoms with water. Oxygen abstraction and intermolecular formaldehyde generation mechanisms; An MCSCF study

Reactions of singlet and triplet carbon atoms with water are explored theoretically using CASSCF–MCQDPT2, CCSD, and DFT methodologies. The ¹S carbons are found to be unreactive. Depending on the carbon atom generation method and the reaction medium, gas‐phase C(³P) attacking water may generate CO and atomic hydrogen as the end products. Reaction paths of the C(¹D) + H₂O system are complicated due to the involvement of two reactive potential energy surfaces with branchings occurring along each. Modifications in product distributions for reactions taking place in condensed phases are elaborated. The decisive reaction conditions, under which the oxygen abstraction and intermolecular formaldehyde generation dominate, are suggested to clarify the discrepancy related with experimental CO observation. The findings are consistent with available experimental data on this system. Oxygen abstraction and intermolecular formaldehyde generation mechanisms suggested here are capable of serving as models for similar reactions of alcohols. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2012     

Au+(1S, 3D)与N2O(1Σ+)反应机理的理论研究

采用密度泛函B3LYP方法, O和N用6-311+G*基组, Au+用赝势基组(8s7p6d)/[6s5p3d], 研究了Au+(1S, 3D)离子和N2O(1Σ+)分子的反应机理. 报道了在基态单重态和激发三重态势能面上各反应物、中间体和过渡态的构型特征及能量. 结果表明, 两个主反应通道Au+(1S)+ N2O(1Σ+)→1NA-Complex-1→1NA-TS1→1NA-Complex-2→1NA-Crossing→[3OAuNN]+和Au+(1S)+ N2O(1Σ+)→1NB-Complex→1NB-Crossing→[AuNN(1Σ+)]++O(3P)都需经过反应交叉势能面, 出现“系间窜越”. 用内禀坐标单点计算垂直激发态的方法确定了势能面交叉点, 并用含时密度泛函TD-B3LYP方法进一步探讨了自旋翻转机理.     

Computational study of carbon atom (3P and 1D) reaction with CH2O. Theoretical evaluation of 1B1 methylene production by C (1D)

Singlet and triplet free energy surfaces for the reactions of C atom ((3)P and (1)D) with CH(2)O are studied computationally to evaluate the excited singlet ((1)B(1)) methylene formation from deoxygenation of CH(2)O by C ((1)D) atom as suggested by Shevlin et al. Carbon atoms can react by addition to the oxygen lone pair or to the C=O double bond on both the triplet and singlet surfaces. Triplet C ((3)P) atoms will deoxygenate to give CO plus CH(2) ((3)B(1)) as the major products, while singlet C ((1)D) reactions will form ketene and CO plus CH(2) ((1)A(1)). No definitive evidence of the formation of excited singlet ((1)B(1)) methylene was found on the singlet free energy surface. A conical intersection between the (1)A' and (1)A' ' surfaces located near an exit channel may play a role in product formation. The suggested (1)B(1) state of methylene may form via the (1)A' ' surface only if dynamic effects are important. In an effort to interpret experimental observation of products trapped by (Z)-2-butene, formation of cis- and trans-1,2-dimethylcyclopropane is studied computationally. The results suggests that "hot" ketene may react with (Z)-2-butene nonstereospecifically.     

Reactions of (Me2N)3P with functionalized di- and trichlorocyclopentenones

2,3-Dichloro-4,4-ethylenedioxycyclopent-2-enone, its 5-chloroderivative, and 5-allyl-2,3,5-trichloro-4,4-dimethoxycyclopent-2-enone react with (Me₂N)₃P to give the corresponding products of substitution of the NMe₂ group for the vinylic Cl atom at C(3). Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2555–2556, December, 1998.     

A theoretical study of the fluoride exchange between UO2F+(aq) and UO2 2+(aq)

Experimental data on the thermodynamics and reaction mechanism of the inner-sphere fluoride exchange reaction U17O2(2+) + UO2F+ <==> U17O2F+ + UO2(2+) have been compared with different intimate reaction mechanisms using quantum chemical methods. Two models have been tested that start from the outer sphere complexes, (H2O)[U(A)O2F(OH2)4+]...[U(B)O2(OH2)5(2+)] and [U(A)O2F(OH2)4+]...[U(B)O2(OH2)5(2+)]; the geometry and energies of the intermediates and transition states along possible reaction pathways have been calculated using different ab initio methods, SCF, B3LYP and MP2. Both the experimental data and the theoretical results suggest that the fluoride exchange takes place via the formation and breaking of a U-F-U bridge that is the rate determining step. The calculated activation enthalpy DeltaH( not equal) = 30.9 kJ mol(-1) is virtually identical to the experimental value 31 kJ mol(-1); however this agreement may be a coincidence as we do not expect a larger accuracy than 10 kJ mol(-1) with the methods used. The calculations show that the fluoride bridge is formed as an insertion of U(A)O2)F(OH2)4+ into U(B)O2(OH2)5(2+) followed by a subsequent transfer of water from the first to the second coordination sphere of U(B).