Effective core potential studies of transition metal bonding, structure and reactivity

Gordon, Mark S.; Cundari, Thomas R.

doi:10.1016/0010-8545(95)01133-1

Cited by 77 publications

(35 citation statements)

References 84 publications

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“…19 The nature of chemical bonding in transition metal complexes can be analyzed and interrelations between complex ab initio calculations and a simple valence bond approach revealed using the MCSCF/LMO/CI scheme. 20 The approach includes construction of the CASSCF wave function, derivation of MOs localized on atoms to the greatest extent, and construction of the CI wave function with the active space including the localized orbitals. As a result, one obtains (i) contributions of each structure to the wave function of the system and (ii) configurations similar to resonance structures.…”

Section: Resultsmentioning

confidence: 99%

Alkane activation by silica supported Group VB metal hydrides. A quantum-chemical study

Михайлов

Kustov

2005

Russ Chem Bull

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A quantum chemical study of alkane hydrogenolysis and metathesis on silica supported Group VB metal hydrides (M = V, Nb, Ta) was carried out. Using a model fragment with the β crystobalite structure permits a correct description of the properties of the grafted organome tallic complexes. Alkane hydrogenolysis and metathesis reactions involve (i) π complexes and carbene complexes of M V and (ii) alkyl derivatives of M III as possible intermediates. The character of the potential energy surfaces of the key alkane transformations points to an important role of triplet states in the catalytic processes involving niobium and vanadium. An alternative low energy reaction pathway characterized by a change in the spin state was found.Key words: activation of alkanes, hydrogenolysis of alkanes, metathesis of alkanes, surface metal complexes, Group VB metal hydrides, quantum chemical calculations, ab initio quan tum chemical calculations.

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Section: Resultsmentioning

confidence: 99%

Alkane activation by silica supported Group VB metal hydrides. A quantum-chemical study

Михайлов

Kustov

2005

Russ Chem Bull

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“…Thus, occupation numbers between 1.90 and 0.10 are found for the stretched ethylene bond, and can be considered an indication of considerable multireference character. [19] In Table 1, the MP2 occupation numbers of the frontier orbitals in the retinal chromophore are shown. Here, occupation numbers that deviate significantly from 2 to 0 are already apparent in the ground state structure.…”

Section: %270mentioning

confidence: 99%

Polarizable embedding based on multiconfigurational methods: Current developments and the road ahead

Hedegård

Jensen

Kongsted

2014

Int J of Quantum Chemistry

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This perspective gives a brief overview of recent developments within the polarizable embedding (PE) method -a multiscale approach developed over the last years. In particular, we are concerned with a recent coupling of the PE method to a multiconfiguration self-consistent field (MCSCF) code. Current applications and target systems are outlined, and methods to incorporate dynamical correlation are discussed. With respect to dynamical correlation, the focus is on perturbative treatments as well as a range-separated multiconfigurational hybrid between MCSCF and density functional theory (MC-srDFT). A short discussion of CAS active spaces is also given. A few sample results using a retinal chromophore surrounded by a protein environment illustrate both the importance of the choice of active space and the importance of dynamical correlation.

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“…Brown and Kent [5] clarified some of these points when they reported a detailed structural characterization in solution of the intermediates and their interconversion pathways for the hydroformylation catalyzed by HRh(CO)(PPh 3 ) 3 , using 1 H, 13 C, and 31 P NMR experiments. This study gave support for the mechanistic proposal of the Montedison group [6] in which the regioselectivity is controlled by a competitive trapping of the olefin by coordinately unsaturated intermediates HRh(CO)(PPh 3 ) 2 and HRh(CO) 2 (PPh 3 ).…”

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confidence: 95%

Insertion reaction of propene into Rh?H bond in HRh(CO)(PH3)2(C3H6) compound: A density functional study

Rocha

Almeida

2000

Int. J. Quant. Chem.

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ABSTRACT:Quantum mechanical calculations at the MP4 (SDQ) level using the BP86-optimized geometries were carried out to investigate the energies and reaction mechanism for the propene (CH 3 -C 1 H=CH 2 2 ) insertion reaction into the Rh-H bond, using the cis-HRh(CO)(PH 3 ) 2 compound as a model catalytic species. Since the reaction may occur on the branched carbon 1 or in the normal carbon 2, which leads to branched and normal Rh(alkyl) compounds, respectively, we investigated these two mechanisms. The results show that the insertion in the branched carbon has an activation energy of 16.2 kcal/mol, and the activation energy for the reaction to take place at the normal carbon is 14.3 kcal/mol. These activation energies, together with the calculated relative energy of the metal-alkyl compounds formed after the insertion considering these two pathways, were used to access the regioselectivity on this reaction. We found a ratio of normal-and iso-products, n:iso, of (96:4), which is in excellent agreement with the experimental regioselectity of (95:5).

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Effective core potential studies of transition metal bonding, structure and reactivity

Cited by 77 publications

References 84 publications

Alkane activation by silica supported Group VB metal hydrides. A quantum-chemical study

Alkane activation by silica supported Group VB metal hydrides. A quantum-chemical study

Polarizable embedding based on multiconfigurational methods: Current developments and the road ahead

Insertion reaction of propene into Rh?H bond in HRh(CO)(PH3)2(C3H6) compound: A density functional study

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