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A systematic investigation on the SN2 displacement reactions of nine carbene radical anions toward the substrate CH3Cl has been theoretically carried out using the popular density functional theory functional BHandHLYP level with different basis sets 6-31+G (d, p)/relativistic effective core potential (RECP), 6-311++G (d, p)/RECP, and aug-cc-pVTZ/RECP. The studied models are CX1X2•− + CH3Cl → X2X1CH3C• + Cl−, with CX1X2•− = CH2•−, CHF•−, CHCl•−, CHBr•−, CHI•−, CF2•−, CCl2•−, CBr2•−, and CI2•−. The main results are proposed as follows: (a) Based on natural bond orbital (NBO), proton affinity (PA), and ionization energy (IE) analysis, reactant CH2•− should be a strongest base among the anion-containing species (CX1X2•−) and so more favorable nucleophile. (b) Regardless of frontside attacking pathway or backside one, the SN2 reaction starts at an identical precomplex whose formation with no barrier. (c) The back-SN2 pathway is much more preferred than the front-SN2 one in terms of the energy gaps [Δ E [ABSTRACT FROM AUTHOR]

A systematic investigation on the H‐abstraction reactions of 8 carbene radical anions with CCl3H has been performed theoretically using the popular DFT functional BHandHLYP/aug‐cc‐pVTZ/RECP level of theory. As a result, our studies strongly suggest that the reactivity of the title reactions (CX1X2•− + CCl3H) present increase in the order: CHI•− < CHBr•− < CHCl•− < CHF•− for first halogen CHX•− and CCI2•− < CBr2•− < CCl2•− < CF2•− for second halogen CX2•−, more important, the reactions of the former exhibit more activity than those of corresponding the latter. Moreover, based on the NBO analysis, the Activation Strain model analysis and the correlations analyses of activation barrier with both PA and IE, respectively, we further confirm over the conclusion. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011 [ABSTRACT FROM AUTHOR]

Abstract: A theoretical investigation at DFT (B3LYP) level on the cyclopropanation reactions catalyzed by nickel(0) and nickel(II) have been extensively investigated. The computation results show that the active catalytic species formed by a CH2 fragment and the Cl2Ni(PH3)2 is carbenoids (PH3)2Ni(CH2Cl)Cl (IMA) and (PH3)Ni(CH2PH3)Cl2 (IMB), but both the carbenes (Cl2NiCH2 (IMC), (PH3)3NiCH2 (IME) and (PH3)2NiCH2 (IMG)) and carbenoids (ClNiCH2Cl (IMD), Ni(CH2PH3)(PH3)2 (IMF) and Ni(CH2PH3)PH3 (IMH)) are active catalytic species obtained from NiCl2, Ni(PH3)3, Ni(PH3)2 and a CH2 fragment. The cyclopropanation reaction proceeds through either concerted or multistep reaction pathway. The most favor cyclopropanation reactions catalyzed by nickel(II) is multistep pathway for IMD with a barrier of 21.65kcalmol−1 but is endothermic 6.74kcalmol−1, and the most favor nickel(0) catalyzed cyclopropanation reactions is also multistep pathway for IME, IMH and IMG species all with barriers of 21.93kcalmol−1 but the downhill potential energy surface discloses that each step of the cyclopropanation reaction are all irreversible. Thus, nickel(0) catalyzed cyclopropanation reaction proceed easer than nickel(II). [Copyright &y& Elsevier]

The mechanisms of the reaction of lanthanide ions (Ce and Pr) with the carbon dioxide were investigated at the B3LYP level of theory. The crossing points (CPs) between the different potential energy surfaces (PESs) have been located by means of the intrinsic reaction coordinate approach used by Yoshizawa et al., and corresponding minimum energy crossing points (MECPs) that we obtained by the mathematical algorithm proposed by Harvey et al. has also been used. In addition, possible spin inversion processes are discussed by means of spin-orbit coupling (SOC) calculations. The value of 61.68 cm (for MECP) and 69.17 cm (for MECP) for the SOC constants indicates that the spin crossing process in Ln + CO (∑) reaction can be occurred efficiently because of the large SOC involved. And the O-atom affinities (OA) testified that the argumentation is thermodynamically allowed. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011 [ABSTRACT FROM AUTHOR]

Abstract: A systematic theoretical study of the reaction NO2(2A1)+CO(1∑+)→NO(2∏)+CO2(1∑g +) catalyzed by Ti+ has been investigated by means of UB3LYP/6-311+G(2d) level. Our calculated results sharply reveal that both NO2(2A1)+Ti+(X4F)→NO(2∏)+TiO+(X2Δ) and TiO+(X2Δ)+CO(1∑+)→Ti+(X4F) + CO2(1∑g +) are spin-forbidden reactions. The minimum-energy crossing points (MECPs) that are involved have been characterized at the same level and the possible spin inversion processes are discussed using the intrinsic reaction coordinate (IRC) approach. [Copyright &y& Elsevier]

Abstract: The gas-phase reaction of activation of C–C double bond of C2H4 by has been investigated using density functional theory (DFT) at the UB3LYP/6-311G(2d,p) level. The calculation results show that the reaction experiences rearranged process. On the basis of Hammond postulate, this is a typical ‘two-state reactivity’ (TSR) reaction. The involving crossing between the singlet and triplet potential energy surfaces has been discussed by means of the intrinsic reaction coordinate (IRC) approach used by Yoshizawa et al., and a minimum energy crossing point (MECP) that we obtained by the mathematical algorithm proposed by Harvey et al. has been also employed. [Copyright &y& Elsevier]

Abstract: The gas-phase reaction of N2O and CO catalyzed by Pt+ has been investigated by means of the relativistic effective core potential (RECP) of Stuttgart basis sets on platinum and UB3LYP/6-311+G(2d) level on nonmetal atoms. The involving crossings between the doublet and quartet potential energy surfaces have been discussed by means of the intrinsic reaction coordinate approach used by Yoshizawa et al, and corresponding MECPs we obtained by the mathematical algorithm proposed by Harvey et al. has also been employed. In addition, the crossing caused by SOC is efficient. And the O-atom affinities (OA) testified that the argumentation is thermodynamically allowed. [Copyright &y& Elsevier]

Abstract: The reactivity of X(3P) (X=Ge, Sn, Pb) with N2O(X1Σ) on both singlet and triplet potential energy surfaces have been investigated at the B3LYP level of theory. To accurately evaluate the activation barrier and reaction energy, the coupled cluster single point calculations using the B3LYP structures is performed. The calculated results are in good agreement with experimental observations. The (X=Ge, Sn, and Pb) reactions that Arthur Fontijn has been observed are spin-forbidden for formation of ground state products in the experiments. The present paper is discussed with the aid of the direct abstraction (DA) mechanism (also called the surface crossing model), a correlation argument based on separated fragments X+O+N2 can explain the inefficiency of the (X=Ge, Sn, and Pb) reactions at 298K by the need to switch electron configurations along low-energy adiabatic paths from ground-state reactants to energetically accessible product states. [Copyright &y& Elsevier]

In this paper, the mechanisms of H 2 evolution on Pt 6 , Pt 5 Sn 5 , and Pt 3 Sn 6 clusters were respectively investigated by the B3LYP method of density functional theory (DFT). The B3LYP functional with non-local dispersion corrections (B3LYP-D3) method were performed to investigate the adsorption of H and H + on clusters. The calculation results indicated that the adsorption energy of H on Pt reduced due to the interaction of Sn and Pt, which promoted H desorption from Pt to form H 2 . Meanwhile, Sn atom of Pt 5 Sn 5 and Pt 3 Sn 6 clusters had strong interaction with H + due to the existence of Pt, which was benefit for the reduction of H + on Sn atom. As a consequence, Pt 5 Sn 5 and Pt 3 Sn 6 showed lower potential barrier and higher activities than Pt for H 2 evolution. The potential barriers of H 2 formation over Pt 3 Sn 6 clusters was only 11.1% of that over Pt cluster. [ABSTRACT FROM AUTHOR]