Effective Core Potential Approaches to the Chemistry of the Heavier Elements

Cundari, Thomas R.; Benson, Michael; Lutz, Matthias; Sommerer, Shaun O.

doi:10.1002/9780470125854.ch3

Cited by 80 publications

(22 citation statements)

References 180 publications

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“…Quantum chemical methods have become useful and practical tools in study of TM complexes (14)(15)(16)(17). Particularly, advancements in density functional theory (DFT) (16) and the use of effective core potentials (14,15) have made qualitatively accurate predictions of the structures and chemistry of TM complexes possible at a reasonable computational cost (17).…”

Section: Metal-alkane Binding Energies Have Been Calculated For [Cprementioning

confidence: 99%

“…Particularly, advancements in density functional theory (DFT) (16) and the use of effective core potentials (14,15) have made qualitatively accurate predictions of the structures and chemistry of TM complexes possible at a reasonable computational cost (17). The goals of the present work are twofold: to make computational predictions of the relative stabilities of a selection of alkane -complexes, which will aid synthetic chemists in their efforts toward isolating and fully characterizing such species, and to explain the nature of the alkane-metal interaction in such complexes.…”

Section: Metal-alkane Binding Energies Have Been Calculated For [Cprementioning

confidence: 99%

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Theoretical study of the rhenium–alkane interaction in transition metal–alkane σ-complexes

Cobar

Khaliullin

Bergman

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

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Metal-alkane binding energies have been calculated for [CpRe(CO) 2](alkane) and [(CO)2M(C5H4)C'C(C5H4)M(CO)2](alkane), where M ‫؍‬ Re or Mn. Calculated binding energies were found to increase with the number of metal-alkane interaction sites. In all cases examined, the manganese-alkane binding energies were predicted to be significantly lower than those for the analogous rhenium-alkane complexes. The metal (Mn or Re)-alkane interaction was predicted to be primarily one of charge transfer, both from the alkane to the metal complex (70 -80% of total charge transfer) and from the metal complex to the alkane (20 -30% of the total charge transfer).binding energy ͉ COH activation ͉ DFT calculations ͉ manganese C arbon-hydrogen (COH) bond activation reactions are important from a fundamental point of view, as well as in more practical terms to medicine, academia, and industry, as they are being used for the conversion of common, inexpensive alkanes into reactive (and physiologically active) molecules (1, 2). Many transition metal complexes are now known that can be used to activate COH bonds in alkanes (3). With low-valent metal complexes, the first bond-breaking step involves oxidative addition of an alkane to an unsaturated metal center (Fig. 1). The goal of subsequent steps is to convert the alkyl group R into an alcohol ROH or other potentially useful functionalized organic molecule.Many researchers today are focusing on the development of industrially practical organometallic oxidation catalysts (5-8), but there remain fundamental aspects of the COH activation process that are not fully understood. For instance, it is widely accepted that COH activation reactions proceed via alkane -complex intermediates (3) (Fig. 1, compound 3), and such species have recently been detected and studied in lowtemperature NMR experiments (9-11). Although complexes with intramolecular COH/metal (so-called agostic) interactions have been isolated and crystallographically characterized (3), in systems where strong evidence has been provided for intermolecular metal-alkane coordination in solution (9-11), isolation and solid state structural characterization have not yet been accomplished.† † Intermolecular metal-alkane complexes are therefore one of the most important targets in the study of COH activation; an understanding of the mechanisms of COH activation, which will allow researchers to better control and manipulate the outcome of the reactions, is crucial for the advancement of this area of chemistry.Quantum chemical methods have become useful and practical tools in study of TM complexes (14-17). Particularly, advancements in density functional theory (DFT) (16) and the use of effective core potentials (14, 15) have made qualitatively accurate predictions of the structures and chemistry of TM complexes possible at a reasonable computational cost (17). The goals of the present work are twofold: to make computational predictions of the relative stabilities of a selection of alkane -complexes, which will aid synthetic chemists in th...

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Section: Metal-alkane Binding Energies Have Been Calculated For [Cprementioning

confidence: 99%

Section: Metal-alkane Binding Energies Have Been Calculated For [Cprementioning

confidence: 99%

Theoretical study of the rhenium–alkane interaction in transition metal–alkane σ-complexes

Cobar

Khaliullin

Bergman

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

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“…The model core potential (MCP) [82][83][84] is an extension to the effective core potentials [85,86] with the proper consideration of the nodal structure of valence orbitals. MCP can be generated for heavy atoms using high level relativistic calculations [87].…”

Section: Introductionmentioning

confidence: 99%

Analytic gradient and molecular dynamics simulations using the fragment molecular orbital method combined with effective potentials

2012

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The completely analytic energy gradients are derived and implemented for the two-body fragment molecular orbital (FMO2) method combined with the model core potentials (MCP) and effective fragment potentials (EFP). The many-body terms in EFP require solving coupled-perturbed Hartree-Fock equations, which are derived and implemented. The molecular dynamics (MD) simulations are performed using the FMO2/MCP method for the capped alanine decamer and with the FMO2/EFP method for the zwitterionic conformer of glycine tetramer immersed in the water layer of 6.0 Å (135 water molecules). The results of the MD simulations using the FMO2/EFP and FMO2/MCP gradients show that the total energy is conserved at the time steps less than 1 fs.

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“…Accordingly, a transferable potential can be applied, which mimics the effects of this subvalence electron density on the outer electrons. 103 When ab initio calculations are performed with pseudopotentials, the electron density obtained is a valence density, which could be strictly the valence density as understood in a chemical context, or it may extend up to one subvalence shell depending on the pseudopotential applied. 104 We can then use the resulting valence densities in the evaluation of the MQSM in Eq.…”

Section: Electron Densities For Molecular Quantum Similaritymentioning

confidence: 99%

“…Pseudopotentials, also known as effective core potentials (ECPs), are techniques that help reduce the computational cost of ab initio calculations 103 by replacing the core electrons with a fixed potential. In that way, no effort needs to be spent on determining the orbitals for the subvalence electrons.…”

Section: Electron Densities For Molecular Quantum Similaritymentioning

confidence: 99%