An ab initio calculation was performed on the electronic structures of MoS,MoS_4^(2-) and Mo_2S_2 using relativistic effective core potential(RECP)for molybdenum,and non-relativistic ECP for sulfur.We predicted that t...An ab initio calculation was performed on the electronic structures of MoS,MoS_4^(2-) and Mo_2S_2 using relativistic effective core potential(RECP)for molybdenum,and non-relativistic ECP for sulfur.We predicted that the equilibrium bond length and the dissociation energy of MoS in ground state are 3.89 a.u.and 4.67 eV,respectively,and that the bond is a triple-bond.The ground state of MoS_4^(2-) in Td symmetry is ~1A_1 and π-bonding dominates σ-donation in the molybdenum- sulfur interaction.The Mo_2S_2 is a model contracted from bi-nuclear sulfur-bridged clusters,and the bonding orbitals 1 b_(1u),1b_1g and 1b_2g make the dominant contribution to the stabilization of sulfur- bridged species.展开更多
Ab initio method, under the effective core potential(ECP) approximation at HF/LANL2DZ level, has been employed to study the reaction mechanism of the carbonyl insertion of olefin hydroformylation catalyzed by a carbo...Ab initio method, under the effective core potential(ECP) approximation at HF/LANL2DZ level, has been employed to study the reaction mechanism of the carbonyl insertion of olefin hydroformylation catalyzed by a carbonyl cobalt HCo(CO)_3. The two reaction paths have been discussed. The calculated potential energy barriers for the carbonyl migration and the ethyl group migration are 105. 0 kJ/mol and 39. 17 kJ/mol, respectively. The results indicate that the reaction path via ethyl migration is more energetically favorable than that via carbonyl insertion.展开更多
The interactions between metal ions such as Zn2+, Pb2+, Mn2+, Hg2+, Cd2+, Ni2+ and chitosan have been investigated using the model cluster model method and density functional method. Full optimization and frequency an...The interactions between metal ions such as Zn2+, Pb2+, Mn2+, Hg2+, Cd2+, Ni2+ and chitosan have been investigated using the model cluster model method and density functional method. Full optimization and frequency analysis of all cluster models have been performed employing B3LYP hybrid method at 3-21G basis set level except metal ions which were invoked to use effective core potential (ECP) method. The energy changes, and the main structural parameters have been obtained during the theoretical study of the adsorption of metal ions on the chitosan. The calculations showed that the coordination modes of metal ions with chitosan models were different, the geometries of Mn2+, Zn2+, Cd2+, Hg2+, Pb2+ ions coordinated with two nitrogen atoms and two oxygen atoms were distorted tetrahedral, while the square planar structure of Ni2+ coordinated two nitrogen atoms and two oxygen atoms was observed. The heat of reaction between six metal ions and chitosan models showed the order: Mn2+ >Ni2+ >Zn2+ >Pb2+ >Hg2+ >Cd2+, this suggested that the coordination strength of Mn2+ >Ni2+ >Zn2+ >Pb2+ >Hg2+ >Cd2+.展开更多
The [Os(PH3)4H(H2)]+ system was studied using the Gaussian 88 and the energy gradient technique at the restricted Hartree-Fock level under the effective core potential (ECP) approximation. The two different isomers of...The [Os(PH3)4H(H2)]+ system was studied using the Gaussian 88 and the energy gradient technique at the restricted Hartree-Fock level under the effective core potential (ECP) approximation. The two different isomers of complex [Os(PH3)4H (H2)] (cis and trans) were optimized, and several orientations of the hydrogen molecule were considered for the cis isomer. When the hydride is placed in the cis position and oriented suitably, there is a strongly attractive effect between it and the molecular hydrogen.展开更多
Using the density functional method B3LYP with relativistic effective core potential （RECP） for Pu atom, the low-lying excited states （^4Σ^＋, ^6Σ^＋, ^8Σ^＋） for three structures of PuOH molecule were optimize...Using the density functional method B3LYP with relativistic effective core potential （RECP） for Pu atom, the low-lying excited states （^4Σ^＋, ^6Σ^＋, ^8Σ^＋） for three structures of PuOH molecule were optimized. The results show that the ground state is X^6Σ^＋ of the linear Pu-O-H （C∞v）, its corresponding equilibrium geometry and dissociation energy are RPu-O = 0.20595 nm, RO-H=0.09581 nm and -8.68 eV, respectively. At the same time, two other metastable structures [PuOH （Cs） and H-Pu-O （C∞v）] were found. The analytical potential energy function has also been derived for whole range using the many-body expansion method. This potential energy function represents the considerable topographical features of PuOH molecule in detail, which is adequately accurate in the whole potential surface and can be used for the molecular reaction dynamics research.展开更多
The whole catalytic cycle of the carbonylation of methanol to acetic acid catalyzed by Rh complex is theoretically studied. All structural geometries of reactant, intermediates, transition states and product are optim...The whole catalytic cycle of the carbonylation of methanol to acetic acid catalyzed by Rh complex is theoretically studied. All structural geometries of reactant, intermediates, transition states and product are optimized at HF/LANL2DZ level under the ECP approximation. The potential energy profiles for elementary reactions of carbonylation are calculated respectively. The transition states are further confirmed by having one and only one imaginary vibrational frequency. The results indicate that the activation energy values of CHin3I oxidative addition, carbonyl insertion and CH3COI reductive elimination fundamental steps are 216.03, 128.10 and 126.55 kJ/mol, respectively; and that the CH3I oxidative addition step is predicted to be the rate-determining one.展开更多
文摘An ab initio calculation was performed on the electronic structures of MoS,MoS_4^(2-) and Mo_2S_2 using relativistic effective core potential(RECP)for molybdenum,and non-relativistic ECP for sulfur.We predicted that the equilibrium bond length and the dissociation energy of MoS in ground state are 3.89 a.u.and 4.67 eV,respectively,and that the bond is a triple-bond.The ground state of MoS_4^(2-) in Td symmetry is ~1A_1 and π-bonding dominates σ-donation in the molybdenum- sulfur interaction.The Mo_2S_2 is a model contracted from bi-nuclear sulfur-bridged clusters,and the bonding orbitals 1 b_(1u),1b_1g and 1b_2g make the dominant contribution to the stabilization of sulfur- bridged species.
文摘Ab initio method, under the effective core potential(ECP) approximation at HF/LANL2DZ level, has been employed to study the reaction mechanism of the carbonyl insertion of olefin hydroformylation catalyzed by a carbonyl cobalt HCo(CO)_3. The two reaction paths have been discussed. The calculated potential energy barriers for the carbonyl migration and the ethyl group migration are 105. 0 kJ/mol and 39. 17 kJ/mol, respectively. The results indicate that the reaction path via ethyl migration is more energetically favorable than that via carbonyl insertion.
基金The Ph. D. Foundation (Y030426) and Post-doctoral Foundation of China University of Petroleum (East China).
文摘The interactions between metal ions such as Zn2+, Pb2+, Mn2+, Hg2+, Cd2+, Ni2+ and chitosan have been investigated using the model cluster model method and density functional method. Full optimization and frequency analysis of all cluster models have been performed employing B3LYP hybrid method at 3-21G basis set level except metal ions which were invoked to use effective core potential (ECP) method. The energy changes, and the main structural parameters have been obtained during the theoretical study of the adsorption of metal ions on the chitosan. The calculations showed that the coordination modes of metal ions with chitosan models were different, the geometries of Mn2+, Zn2+, Cd2+, Hg2+, Pb2+ ions coordinated with two nitrogen atoms and two oxygen atoms were distorted tetrahedral, while the square planar structure of Ni2+ coordinated two nitrogen atoms and two oxygen atoms was observed. The heat of reaction between six metal ions and chitosan models showed the order: Mn2+ >Ni2+ >Zn2+ >Pb2+ >Hg2+ >Cd2+, this suggested that the coordination strength of Mn2+ >Ni2+ >Zn2+ >Pb2+ >Hg2+ >Cd2+.
文摘The [Os(PH3)4H(H2)]+ system was studied using the Gaussian 88 and the energy gradient technique at the restricted Hartree-Fock level under the effective core potential (ECP) approximation. The two different isomers of complex [Os(PH3)4H (H2)] (cis and trans) were optimized, and several orientations of the hydrogen molecule were considered for the cis isomer. When the hydride is placed in the cis position and oriented suitably, there is a strongly attractive effect between it and the molecular hydrogen.
文摘Using the density functional method B3LYP with relativistic effective core potential （RECP） for Pu atom, the low-lying excited states （^4Σ^＋, ^6Σ^＋, ^8Σ^＋） for three structures of PuOH molecule were optimized. The results show that the ground state is X^6Σ^＋ of the linear Pu-O-H （C∞v）, its corresponding equilibrium geometry and dissociation energy are RPu-O = 0.20595 nm, RO-H=0.09581 nm and -8.68 eV, respectively. At the same time, two other metastable structures [PuOH （Cs） and H-Pu-O （C∞v）] were found. The analytical potential energy function has also been derived for whole range using the many-body expansion method. This potential energy function represents the considerable topographical features of PuOH molecule in detail, which is adequately accurate in the whole potential surface and can be used for the molecular reaction dynamics research.
基金the Young Teachers' Foundation of Beijing University of Chemical Technology (Grant No. QN0018).
文摘The whole catalytic cycle of the carbonylation of methanol to acetic acid catalyzed by Rh complex is theoretically studied. All structural geometries of reactant, intermediates, transition states and product are optimized at HF/LANL2DZ level under the ECP approximation. The potential energy profiles for elementary reactions of carbonylation are calculated respectively. The transition states are further confirmed by having one and only one imaginary vibrational frequency. The results indicate that the activation energy values of CHin3I oxidative addition, carbonyl insertion and CH3COI reductive elimination fundamental steps are 216.03, 128.10 and 126.55 kJ/mol, respectively; and that the CH3I oxidative addition step is predicted to be the rate-determining one.
