MPW1PW91 Methods Research Articles

Hydroxyl Radical Reactivity with Cytosine and Thymine: A Computational Study

Addition of hydroxyl radical (OH) at the different sites of cytosine and thymine were studied at the different levels of theory of the density functional theory (DFT). All the molecular geometries were optimized at B3LYP, B3PW91, WB97XD, and MPW1PW91 methods with 6-31G (d,p) basis set. The binding energies at the different sites of these two DNA bases were calculated at all the mentioned levels of theory in gas phase and also in different solvents of dielectric constant varying from lower to higher values. The dependence of binding energies in water, methanol, ethanol, acetone, toluene and benzene reveals that binding energies are not much affected by salvation.

Molecular structure, X-ray crystallography, spectroscopic characterization, solvent effect, NLO, NBO, FMO analysis of [Cu(bpabza)] complexe

In this work, first, the new asymmetric carboxamide ligand of (H2bpabza) was synthesized in the laboratory and it was used to make [Cu(bpabza)] complex. Then, FT IR and NMR spectra and X-ray crystallography were used to examine the structure of tetradentate ligand N,N′-bis (2-pyridinecarboxamide)-2-aminobenzylamine (H2bpabza) and Cu(II) complex. Next, the structure of ligand and the resulting complex were drawn using Chembio Draw Ultra software and powerful Gaussian 09 software, computational methods of Density Functional Theory (DFT), B3LYP and MPW1PW91 methods with LanL2DZ basis set were used to study the structure of ligand and Cu(II) complex, to optimize them and to examine the bond length and the bond angle and these values were compared with experimental values.Then, polarizability of its atoms was calculated using Mulliken charge and natural atomic charges. Stretching and bending vibrations were calculated by FT IR and were compared with experimental values. Also, the chemical shift of carbons and hydrogens were calculated using Nuclear Magnetic Resonance (NMR). Donor-acceptor interactions and Hyperpolarizability calculations were used to determine the type of electron transfers and the amount of global hardness (η) and global softness (S) of molecule were calculated using the energy difference between the highest occupied molecular orbital (HOMO) to the Lowest unoccupied molecular orbital (LUMO) in the presence of solvents CH3OH, DMSO, C6H6 and CHCl3. Also UV–Vis spectra were calculated in the presence of solvents CH3OH, DMSO, C6H6 and CHCl3. DFT/B3LYP and MPW1PW91 methods with LanL2DZ basis set were used in all computational methods.

Coordination chemistry and bonding analysis of tetranuclear transition metal pyrene sandwich complexes

Geometry optimizations have been performed on the M4(Pyr)2 (M = Ti-Ni, Pd and Pt, Pyr = C16H10) complexes by means of DFT method using BP86 and mPW1PW91 functionals combined to the TZP basis set. The M4 moiety encapsulated between two pyrene ligands tends to establish M-L bonding with various hapticies from η2 to η6. In accordance with the coordination modes, the pyrene behaves as neutral, dianionic, or tetraanionic ligand. For the Ti, V, and Fe, the low-spin (S = 0) and the high-spin (S = 1) structures are isoenergetic, while the Cr, Mn, and Co structures prefer the high-spin states. The Ni, Pd, and Pt structures are more favorable in low-spin state. The zigzag metallic chain is predicted to be more stable than that of the two-dimensional sheet for the Pd complexes. The spin state changes of the studied complexes in their ground states could be characterized in some cases by different molecular structure modifications (structural isomerisation, where structural modifications accompany the spin state modification like as bonds and angles), electronic configurations (low-spin or high-spin), or oxidation states with respect to the metal charges, in agreement with the metal nature. The optimized structures obtained by both BP86 and mPW1PW91 methods are consistent to each other, where the energetic parameters follow similar tendencies regarding the stability order between isomers.

The Allylic Rearrangements (Claisen and Thio-Claisen) and Decomposition Reactions of Allyl Formate and its Sulfur Analogue: Density Function Theory Study and Nucleus-Independent Chemical Shifts

Theoretical studies of the Claisen and thio-Claisen allylic (3,3-sigmatropic) rearrangements and decomposition reactions of allyl formate (1) and allyl dithioformate (2), have been performed using density functional theory (DFT) and B3LYP and MPW1PW91 methods with a 6-31++G** basis set. Of these DFT, the values for activation parameters obtained with the B3LYP/6-31++G** method are in good agreement with the available experimental data. Transition states optimised at the B3LYP/6-31++G** level of theory were used for calculating the nucleus-independent chemical shift (NICS). Our results indicate that the magnitudes of the aromatic characters of the transition states are not in agreement with the activation energies and therefore these reactions are not controlled by aromaticity, but are controlled kinetically by the aromaticity of the transition states.

Studies on structures and electron affinities of the simplest alkyl dithio radicals and their anions with gaussian-3 theory and density functional theory

The equilibrium geometries and electron affinities of the R-SS/R-SS(-)(R=CH₃, C₂H₅, n-C₃H7, i-C₃H₇, n-C₄H₉, t-C₄H₉, n-C₅H₁₁) species have been studied using the higher level of the Gaussian-3(G3) theory and 21 carefully calibrated pure and hybrid density functionals (five generalized gradient approximation (GGA) methods, seven hybrid GGAs, three meta GGA methods, and six hybrid meta GGAs) in conjunction with diffuse function augmented double-ζ plus polarization (DZP++) basis sets. The geometries are fully optimized with each method and discussed. The reliable adiabatic electron affinity has been presented by means of the high level of G3 technique. With the DZP++ DFT method, three measures of neutral/anion energy differences reported in this work are the adiabatic electron affinity, the vertical electron affinity, and the vertical detachment energy. The adiabatic electron affinities, obtained at the BP86, M05-2X, B3LYP, M06, B98, M06-2X, mPW1PW91, HCTH, B97-1, M05, PBE1PBE, and VSXC methods, are in agreement with the G3 results. These methods perform better for EA prediction and are considered to be reliable.

Fourier transform infrared spectra and normal mode analysis of drug molecules: Zidovudine

The FTIR spectra of zidovudine molecule have been recorded in the range 4000–400cm−1. The title compound is used as a drug against AIDS or HIV. The molecular structure, fundamental vibrational frequencies and intensities of vibrational bands are evaluated using density functional theory (DFT) using BLYP, B3LYP, B3PW91 and MPW1PW91 methods with 6-31+G(d,p) standard basis set. Comparison of simulated spectra with the experimental spectrum provides important informations and the ability of the computational method to describe the vibrational modes. These calculations have allowed finding most stable conformational structure of AZT. Calculated results of the title compound indicate that the drug molecule has syn orientation. The glycosidic bond in AZT and a minimum-energy structure in which the glycosy torsion angle χ and torsion angle γ values are consistent with those in the conformation of AZT in the AZT5-triphosphate bound to HIV RT is determined.

Gas Phase Pyrolysis Reaction of 1-pyrazoline: A Theoretical Kinetic Study

We report kinetic and mechanistic studies of nitrogen elimination from 1-pyrazoline and its deuterated derivatives. This study was carried out for the gas phase employing 6-311 + G(d,p) basis sets with B3LYP, MPW1PW91 and PBEPBE methods. This reaction may proceed through two different mechanisms, molecular and radical. The molecular mechanism advances via two different paths and corresponding intermediates. There are either a four-centred cyclic or a six-centred cyclic intermediate as transition states in the molecular mechanism. The calculated kinetic parameters and isotope effects for the molecular mechanism are consistent with experimental results for cyclopropane formation. However, from the kinetic isotope effects point of view, the fit is better for the radical mechanism for propene formation. Considering activation energies, theoretical calculations suggest that the radical mechanism is the less suitable. The B3LYP method results are in a better agreement with the experimental results when considering only computational data.

Theoretical calculations on the mechanisms of the gas‐phase elimination kinetics of 2‐chloro‐1‐phenylethane, 3‐chloro‐1‐phenylpropane, 4‐chloro‐1‐phenylbutane, 5‐chloro‐1‐phenylpentane, and their corresponding chloroalkanes: The effect of the phenyl ring

AbstractThe kinetics and mechanisms of the dehydrochlorination of 2‐chloro‐1‐ phenylethane, 3‐chloro‐1‐phenylpropane, 4‐chloro‐1‐phenylbutane, 5‐chloro‐1‐phenylpentane, and their corresponding chloroalkanes were examined by means of electronic structure calculation using density functional theory methods B3LYP/6–31G(d,p), B3LYP/6–31++G(d,p), MPW1PW91/6–31G(d,p), MPW1PW91/6–31++G(d,p), PBEPBE/6–31G(d,p), and PBEPBE/6–31++G(d,p). The potential energy surface was investigated for the minimum energy path. Calculated enthalpies and energies of activation are in good agreement with experimental values using the MPW1PW91 and B3LYP methods. The transition state of these reactions is a four‐centered cyclic structure. The reported experimental results proposing neighboring group participation by the phenyl group was not supported by theoretical calculations. The rate‐determining process in these reactions is the breaking of ClC bond. The reactions are described as concerted moderately polar and nonsynchronous. © 2011 Wiley Peiodicals, Inc. Int J Chem Kinet 43: 292–302, 2011

DFT calculation of molecular structures and vibrational spectra of antitumor drugs: cis-[Pt(CH 3CN) 2Cl 2

The molecular structure and vibrational frequencies of cis-[Pt(CH 3CN) 2Cl 2] were calculated by five density functional theory (DFT) and HF methods using several basis sets. The theoretical results are discussed and compared with the experimental data. It is remarkable that mPW1PW91 and PBE1PBE methods at SDD basis sets are clearly superior to the remaining density functional methods in predicting the structures of cis-[Pt(CH 3CN) 2Cl 2]. Mean deviation between the calculated harmonic and observed fundamental vibrational frequencies for each method is also calculated. The results indicate that mPW1PW91 and PBE1PBE methods at SDD basis sets are also the best to predict vibrational spectra of cis-[Pt(CH 3CN) 2Cl 2].

Experimental and Theoretical Studies of the Homogeneous, Unimolecular Gas-Phase Elimination Kinetics of Trimethyl Orthovalerate and Trimethyl Orthochloroacetate

The rates of gas-phase elimination of trimethyl orthovalerate and trimethyl orthochloroacetate have been determined in a static system, and the reaction Pyrex vessels have been deactivated with the product of decomposition of allyl bromide. The reactions are unimolecular and follow a first-order rate law. The working temperature and pressure ranges were 313-410 degrees C and 40-140 Torr, respectively. The rate coefficients for the homogeneous reaction are given by the following Arrhenius expressions: for trimethyl orthovalerate: log k (s(-1)) = [(14.00 +/- 0.28) - (196.3 +/- 1.7) (kJ/mol)] (2.303RT)(-1), (r = 0.9999); and for trimethyl orthochloroacetate: log k (s(-1)) = [(13.54 +/- 0.21) - (209.3 +/- 1.9)(kJ/mol)](2.303RT)(-1), (r = 0.9998). The theoretical calculations of the kinetic and thermodynamic parameters were carried out by using B3LYP, B3PW91, MPW1PW91, and PBEPBE methods. The theoretical results show reasonably good agreement with the experimental energy and enthalpy of activation values when using the B3PW91/6-31++G** method for trimethyl orthovalerate and PBEPBE /6-31++G** for trimethyl orthochloroacetate. These calculations suggest a molecular concerted nonsynchronous mechanism where C-OCH(3) bond polarization, in the sense C(delta+)...(delta-)OCH(3), is the rate-determining step. The increase in electron density of the oxygen atom at OCH(3) eases the abstraction of the hydrogen of the adjacent C-H bond in a four-membered cyclic structure to give methanol and the corresponding unsaturated ketal. The electron-donor substituent enhances decomposition rates by stabilizing the positive charge developing in the transition state at the carbon bearing the three methoxy groups, whereas the electron-withdrawing substituent destabilizes this charge, thus retarding the reaction.

Trends of the bonding effect on the performance of DFT methods in electric properties calculations: A pattern recognition and metric space approach on some XY2 (X = O, S and Y = H, O, F, S, Cl) molecules

A test set of 10 molecules (open and ring forms of ozone and sulfur dioxide as well as water and hydrogen sulfide and their respective fluoro- and chloro-substituted analogs) of specific atmospheric interest has been formed as to assess the performance of various density functional theory methods in (hyper)polarizability calculations against well-established ab initio methods. The choice of these molecules was further based on (i) the profound change in the physics between isomeric systems, e.g., open (C(2v)) and ring (D(3h)) forms of ozone, (ii) the relation between isomeric forms, e.g., open and ring form of sulfur dioxide (both of C(2v) symmetry), and (iii) the effect of the substitution, e.g., in fluoro- and chloro-substituted water analogs. The analysis is aided by arguments chosen from the information theory, graph theory, and pattern recognition fields of Mathematics: In brief, a multidimensional space is formed by the methods which are playing the role of vectors with the independent components of the electric properties to act as the coordinates of these vectors, hence the relation between different vectors (e.g., methods) can be quantified by a proximity measure. Results are in agreement with previous studies revealing the acceptable and consistent behavior of the mPW1PW91, B3P86, and PBE0 methods. It is worth noting the remarkable good performance of the double hybrid functionals (namely: B2PLYP and mPW2PLYP) which are for the first time used in calculations of electric response properties.

The interplay between metal–metal bonds, four‐electron donor carbonyl groups, and five‐electron donor nitrosyl groups in highly unsaturated binuclear rhenium carbonyl nitrosyls

AbstractOptimization of structures for the highly unsaturated binuclear rhenium carbonyl nitrosyls Re2(NO)2(CO)n (n = 5, 4) using the MPW1PW91 and BP86 methods of density functional theory indicate complicated potential energy surfaces with eight singlet and three triplet energetically accessible structures for Re2(NO)2(CO)5 and 11 singlet and six triplet energetically accessible structures for Re2(NO)2(CO)4. The lowest energy structure for Re2(NO)2(CO)5 is a singlet predicted to have two bridging nitrosyl groups and a formal ReRe triple bond to give both rhenium atoms the favored 18‐electron configuration. However, other relatively low‐energy structures for Re2(NO)2(CO)5 are found with five‐electron donor bridging nitrosyl groups, four‐electron donor bridging carbonyl groups, and coordinatively unsaturated rheniumatoms. The lowest energy structures for Re2(NO)2(CO)4 are predicted to be unbridged structures having rhenium–rhenium distances short enough for formal triple or even quadruple bonds. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2009

A comparison of C–C rotational barrier in [2]staffane, [2]tetrahedrane and ethane

Analysis of internal rotation about C–C single bond in [2]staffane, [2]tetrahedrane, and ethane has been carried out using HF, B3LYP, B3PW91, MPW1PW91, MP2, QCISD and QCISD(T) methods combined with 6-31G ∗∗, 6-311++G ∗∗ and AUG-cc-PVTZ basis sets. The calculated rotational barriers Δ E and the trend in them depend on basis set and method. Both hyperconjugation interaction, which stabilizes the staggered conformation more than eclipsed one, and steric effect, which is negligible in ethane and is comparable with hyperconjugation interaction in [2]tetrahedrane and [2]staffane, cause the hindered rotation. In addition, the Δ E values are in good agreement with electron charge densities calculated at central C–C bond critical point.

X-ray diffraction and vibrational spectroscopic studies of indolecarboxylic acids and their metal complexes: Part VII. Indole-2-carboxylic acid and catena-poly[[diaquazinc(II)]-bis(μ 2-indole-2-carboxylato-O:O′)

The catena-poly[[diaquazinc(II)]-bis(μ 2-indole-2-carboxylato-O:O′)], [Zn(I2CA) 2(H 2O) 2] n has been synthesized and characterized by X-ray diffraction analysis and the infrared and Raman spectroscopic methods. The co-ordination of the indole-2-carboxylate anion to Zn(II) results in the formation of the [Zn(I2CA) 2(H 2O) 2] n , in which the Zn(II) cations lie on inversion centres in space group P2 1/c, with water ligands in the apical sites of octahedral geometry. Moreover, the infrared and Raman spectra of indole-2-carboxylic acid (I2CA) and the infrared spectrum of deuterated derivative of indole-2-carbocylic acid (I2CA-d2) are recorded in the solid phase. The theoretical wavenumbers, infrared intensities and Raman scattering activities were calculated by density functional B3LYP and mPW1PW91 methods with the 6-311++G(d,p) basis set for I2CA and I2CA-d2 and with the 6-311++G(d,p)/LanL2DZ basis sets for the theoretical model of Zn(I2CA) 2(H 2O) 2] n . The detailed vibrational assignment has been made on the basis of the calculated potential energy distribution for all molecules.

Effect of microsolvation on zwitterionic glycine: an ab initio and density functional theory study

The effect of microsolvation on zwitterionic glycine, considering both (-NH3(+)) as proton donor and (-COO(-)) as proton acceptor at correlated ab initio (MP2) level and density functional methods (B3LYP, PW91, MPW1PW91 and PBE) using 6-311++G** basis set has been reported. DFT methods have been employed so as to compare the performance/quality of different gradient-corrected correlation functionals (PW91, PBE), hybrid functionals (B3LYP, MPW1PW91) and to predict the near quantitative structural and vibrational properties, at reduced computational cost. B3LYP method outperforms among the different DFT methods for the computed hydrogen bond distances and found closer to the value obtained by correlated MP2 level, whereas MPW1PW91 and PBE methods shows very similar values but approximately 0.03 A less, compared to B3LYP method. MP2 calculation and single point CCSD(T)//MP2 calculation have been considered to decompose the interaction energy, including corrections for basis set superposition error (BSSE). Moreover, charge distribution analysis has also been carried out to understand the long raised questions, how and why the two body energies have significant contribution to the total binding energy.

Binuclear manganese and rhenium carbonyls M2(CO)n (n = 10, 9, 8, 7): comparison of first row and third row transition metal carbonyl structures

The equilibrium geometries, thermochemistry, and vibrational frequencies of the homoleptic binuclear rhenium carbonyls Re2(CO)n (n = 10, 9, 8, 7) were determined using the MPW1PW91 and BP86 methods from density functional theory (DFT) with the effective core potential basis sets LANL2DZ and SDD. In all cases triplet structures for Re2(CO)n were found to be unfavorable energetically relative to singlet structures, in contrast to corresponding Mn2(CO)n derivatives, apparently owing to the larger ligand field splitting of rhenium. For M2(CO)10 (M = Mn, Re) the unbridged structures (OC)5M-M(CO)5 are preferred energetically over structures with bridging CO groups. For M2(CO)9 (M = Mn, Re) the two low energy structures are (OC)4M(micro-CO)M(CO)4 with an M-M single bond and a four-electron donor bridging CO group and (OC)4M[double bond, length as m-dash]M(CO)5 with no bridging CO groups and an M[double bond, length as m-dash]M distance suggesting a double bond. The lowest energy structures for Re2(CO)8 have Re[triple bond, length as m-dash]Re distances in the range 2.6-2.7 A suggesting the triple bonds required to give the Re atoms the favored 18-electron configuration. Low energy structures for Re2(CO)7 are either of the type (OC)(4)M[triple bond, length as m-dash]M(CO)3 with short metal-metal distances suggesting triple bonds or have a single four-electron donor bridging CO group and longer M-M distances consistent with single or double bonds. The 18-electron rule thus appears to be violated in these highly unsaturated Re2(CO)7 structures.

X-ray diffraction and vibrational spectroscopic studies of indolecarboxylic acids and their metal complexes: Part VI. Indole-3-propionic acid and catena-poly[(di-μ 3-aqua)(η 2-:-μ 2-indole-3-propionato- O, O′:- O)(μ 3-indole-3-propionato- O)disodium

In the present studies the novel catena-poly[(di-μ 3-aqua)(η 2-:-μ 2-indole-3-propionato- O, O′:- O)(μ 3-indole-3-propionato- O)disodium], [Na 2(I3PA) 2(H 2O) 2] n has been synthesized and characterized by X-ray diffraction analysis and infrared and Raman spectroscopic methods. In the [Na 2(I3PA) 2(H 2O) 2] n , there are two different crystallographic sites for the Na + ions, which are coordinated by six and seven oxygen atoms. Moreover, two O-deprotonated I3PA ions exhibit different coordination modes. One I3PA ion acts as a tetradentate chelating-bridging ligand using two oxygen atoms of the carboxylic group, while the other behaves like a tridentate bridging using one oxygen atom of the carboxylic group, whereas the water molecules act as the tridentate bridging. The crystals of [Na 2(I3PA) 2(H 2O) 2] n are triclinic, space group P 1 ¯ , with a = 6.1281(8), b = 7.5812(9), c = 22.893(3) Å, α = 91.79(1), β = 96.56(1), γ = 90.35(1) o, V = 1056.0(2) Å 3 and Z = 2. Moreover, the infrared and Raman spectra of indole-3-carboxylic acid (I3CA) and indole-3-propionic acid (I3PA) and the infrared spectra of their deuterated derivatives I3CA-d2 and I3PA-d2, respectively, have been recorded in the solid state. Experimental studies were combined with theoretical studies. Theoretical studies were performed using density functional B3LYP and mPW1PW91 methods with the 6-311++G(d,p) basis set for I3CA, I3PA, I3CA-d2, and I3PA-d2. Normal coordinate analysis was employed to obtain a clear-cut assignment of the vibrational spectra indole-3-carboxylic and indole-3-propionic acids, and their deuterated derivatives.

Vibrational spectrum and assignments of 2-(4-methoxyphenyl)-1 H-benzo[ d]imidazole by ab initio Hartree–Fock and density functional methods

The room temperature attenuated total reflection Fourier transform infrared spectrum of the 2-(4-methoxyphenyl)-1 H-benzo[ d]imidazole has been recorded with diamond/ZnSe prism. The conformational behaviour, structural stability of optimized geometry, frequency and intensity of the vibrational bands of the title compound were investigated by utilizing ab initio calculations with 6-311G** basis set at HF, B3LYP, BLYP, B3PW91 and mPW1PW91 levels. The harmonic vibrational frequencies were calculated and scaled values have been compared with experimental IR spectrum. The observed and the calculated frequencies are found to be in good agreement. The theoretical vibrational spectra of the title compound were interpreted by means of potential energy distributions using VEDA 4 program. Furthermore, the optimal uniform scaling factors calculated for the title compound are 0.9120, 0.9596, 0.9660, 0.9699, and 0.9993 for HF, mPW1PW91, B3PW91, B3LYP and BLYP methods, respectively.

Homoleptic Carbonyls of the Second-Row Transition Metals: Evaluation of Hartree-Fock and Density Functional Theory Methods.

The homoleptic mono- and multinuclear carbonyls for Mo, Tc, Ru, and Rh, namely, Mo(CO)6, Ru(CO)5, Tc2(CO)10, Ru3(CO)12, Rh4(CO)12, and Rh6(CO)16, are investigated theoretically by the Hartree-Fock method and three density functional theory (DFT) methods, i.e., BP86, B3LYP, and MPW1PW91, along with the SDD ECP basis sets. The results predicted by all the methods are basically in agreement with each other. The MPW1PW91 and BP86 methods predict geometric parameters and vibrational spectra, respectively, closest to the experimental values. For Ru3(CO)12 the relative energies of the D3h isomer with only terminal CO groups and the C2v isomer with two bridging CO groups are within 3 kcal/mol of each other with the lower energy isomer depending upon the computational method used. For Rh4(CO)12 the global minimum is predicted to have C3v symmetry, with three bridging and nine terminal carbonyls, in accord with experiment. The Rh6(CO)16 structure has Td symmetry and satisfies the Wade-Mingos rules for an octahedral cluster. Using the MPW1PW91 method the Rh-Rh distances in Rh4(CO)12 are found to be 2.692 Å and 2.750 Å and those in Rh6(CO)16 to be 2.785 Å.

DFT studies of the phosphinidene derivative HPNaF and its insertion reaction with R–H(R=F, OH, NH2, CH3)

The formations of the phosphinidene derivative HPNaF and its insertion reactions with R–H (R=F, OH, NH2, CH3) have been systematically investigated employing the density functional theory (DFT), such as the B3LYP and MPW1PW91 methods. A comparison with the results of MP2 calculations shows that MPW1PW91 underestimates the barrier heights for the four reactions considered. Similarly, the same is also true for the B3LYP method depending on the selected reactions, but by much less than MPW1PW91, where the barrier heights of the four reactions are 25.2, 85.7, 119.0, and 142.4 kJ/mol at the B3LYP/6-311+G* level of theory, respectively. All the mechanisms of the four reactions are identical to each other, i.e., an intermediate has been located during the insertion reaction. Then, the intermediate could dissociate to substituted phosphinidane(H2RP) and NaF with a barrier corresponding to their respective dissociation energies. Correspondingly, the reaction energies for the four reactions are −92.2, −68.1, −57.2, and −44.3 kJ/mol at the B3LYP/6-311+G* level of theory, respectively, where both the B3LYP and MPW1PW91 methods underestimate the reaction energies compared with the MP2 results. The linear correlations between the calculated barrier heights and the reaction energies have also been observed. As a result, the relative reactivity among the four insertion reactions should be as follows: H–F > H–OH > H–NH2 > H–CH3.