Binding energy of chromium hexacarbonyl. 2. Revisited with correlation effects

Machado, Francisco B. C.; Davidson, Ernest R.

doi:10.1021/j100119a024

Cited by 24 publications

(61 citation statements)

References 3 publications

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“…The NBOs are depicted by drawing isosurface values of 0.05. The NBO shapes, shown in Figure 5, support the notion that NBO CAS (8,12), suggested by Weinhold's perturbation analysis (see Ref. Bold face numbers 1-12 label the NBOs.…”

Section: Main Features Of the Computational Scheme For Obtaining The supporting

confidence: 75%

“…The NBO shapes, shown in Figure 5, support the notion that NBO CAS (8,12), suggested by Weinhold's perturbation analysis (see Ref. BD in Fe(CO) 5 Evaluated by a FCI in the NLMO CAS (8,12) Above, Weinhold's NBO technique (see Ref. The BD processes turn out to be ETs from the strongly occupied lone pair NBOs 1-4 into the antibond NBOs 5-12.…”

Section: Main Features Of the Computational Scheme For Obtaining The supporting

confidence: 70%

“…The largest E (2) values (bold numbers) suggest an NBO CAS for Fe(CO) 5 made up by the iron d-lone pairs 40-43 and the antibond p* acceptor NBOs 159, 160, 162, 163, 165, 166, 168, and 171. They give rise to an NBO CAS (8,12) where eight electrons occupy four Fe d-type lone pairs in the parent configuration. Those electrons get distributed by a FCI into the manifold of the 12 NBOs depicted in Figure 5.…”

Section: Main Features Of the Computational Scheme For Obtaining The mentioning

confidence: 99%

“…The antibond p*-NBOs 5-12, localized at the CO ligands, have positive NBO energies and smaller electron occupation numbers. In the following section, we use NBO CAS (8,12) of Figure 5 as a guide to determine an NLMO CAS (8,12) for investigating BD in Fe(CO) 5 more quantitatively. [33], section 3.2.3), is appropriate for describing BD of the DCD model operating in Fe(CO) 5 .…”

Section: Main Features Of the Computational Scheme For Obtaining The mentioning

confidence: 99%

“…An FeACO r-bond is formed by electron transfer (ET) from an occupied r molecular orbital (MO) of CO into an empty r-orbital of the central Fe. The operation of the DCD model has been critically discussed for the TMACO bonds of TM carbonyls, [6][7][8][9] the TM¼ ¼CH 2 bond of TM carbenes, [10][11][12][13] and bonds of TMAolefine complexes. [4] Therefore, the central iron atom diminishes this electron excess by an ET from occupied Fe d-orbitals into empty p-MOs of the CO ligands.…”

Section: Introductionmentioning

confidence: 99%

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A quantum chemical calculation on Fe(CO)₅ revealing the operation of the Dewar–Chatt–Duncanson model

Bachler

2012

J Comput Chem

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A nonstandard computational scheme has been applied to calculate Fe(CO)(5) with the aim to illustrate the operation of the Dewar-Chatt-Duncanson model by computation. A full configuration interaction (CI) calculation in an active space has been performed. The active space is built from naturally localized molecular orbitals (NLMOs) localized in bond regions or forming lone pairs. For selecting this active space, Weinhold's perturbation theory formulated in the natural bond orbital (NBO) space has been applied. Bonding, lone pair, and antibond NBOs exhibiting large interaction energies serve to define the active space. The actually applied active space, however, comprises NLMOs that are close in shape to the NBOs indicated by perturbation theory. Thus, a CI calculation with localized orbitals has been performed meeting the classical reasoning of chemists that is often based on local bonding concepts. The computational scheme yields the Lewis structure for Fe(CO)(5) whose energy is identical to the Hartree-Fock energy. The Lewis energy comprises CO → Fe σ-electron transfer (ET) and CO ← Fe electron back donation (BD). This Lewis energy gets lowered by localized correlation energy contributions caused by ET processes where electrons are back donated from the Fe d-lone pairs into the CO ligands. Thus, electron correlation within the selected active space is dominated by electron BD. Energies and electron populations of the NBOs support the notion that electrons are preferentially back donated into the equatorial CO ligands. Weights of local Slater determinants, determining the correlation energy, also point to a predominant BD into the equatorial CO ligands. Correlation energy increments resulting from electron BD into single antibond orbitals of the CO ligands have been calculated. These energy quantities also demonstrate that BD into the equatorial CO ligands is more energy lowering than BD into the axial CO ligands.

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Section: Main Features Of the Computational Scheme For Obtaining The supporting

confidence: 75%

Section: Main Features Of the Computational Scheme For Obtaining The supporting

confidence: 70%

Section: Main Features Of the Computational Scheme For Obtaining The mentioning

confidence: 99%

Section: Main Features Of the Computational Scheme For Obtaining The mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A quantum chemical calculation on Fe(CO)₅ revealing the operation of the Dewar–Chatt–Duncanson model

Bachler

2012

J Comput Chem

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Ethylene coordination, insertion, and chain transfer at a cationic aluminum center: A comparative study withAb Initio correlated level and density functional methods

2000

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The performance of correlated ab initio methods and DFT methods was compared for the propagation and chain transfer steps of ethylene polymerization by a model aluminum–amidinate system, [{HC(NH)2}AlCH2CH3]+. All methods agree that the main chain transfer mechanism is β‐hydrogen transfer to the monomer (BHT), and that this is substantially easier than propagation; implications for the real Jordan system are discussed briefly. Counterpoise corrections are necessary to obtain reasonable olefin complexation energies. Activation energies are consistently lower at DFT (BP86, B3LYP) than at ab initio levels [MP2, MP3, MP4, CI, CCSD(T)]; the differences are particularly large (16 kcal/mol) for the BHT reaction. This is suggested to be related to the known problem of DFT in describing hydrogen bridged systems. © 2000 John Wiley & Sons, Inc. J Comput Chem 21: 398–410, 2000

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Electronic Structure Calculations: Metal Carbonyls

Daniel

2005

Encyclopedia of Inorganic Chemistry

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A survey of the specificities of the electronic structure of transition metal carbonyls is presented, with emphasis on the theoretical complication inherent to the description of this class of molecules. The difficulties originate from the nature of the metal‐carbonyl bonding, which is governed by the electronic configuration of the metal atom. The distribution of the electronic density may vary significantly from first‐row to third‐row transition metals. The presence of several metal centers or other ligands than CO perturbs the well‐balanced repartition driven by the donor‐acceptor capabilities of the metal and the CO groups in “classic” saturated M(CO) n complexes. Quantum chemistry needs highly correlated methods, which are sufficiently flexible to model this electronic flexibility that is at the origin of the chemical richness of transition metal carbonyls. A short review of the appropriate methods, with their advantages and drawbacks, is given in the introductory section. Several classes of transition metal carbonyls are described in the case studies section. The theoretical analysis of electronic ground and excited states properties of neutral and charge M(CO) n saturated first‐, second‐, and third‐row transition metal carbonyls is illustrated for M(CO) 6 (M = Cr, Mo, W), M(CO) 5 (M = Fe, Ru, Os), and M(CO) 4 (M = Ni, Pd, Pt). More predictive theoretical work concerns either the unsaturated species, generated by photofragmentation, which are characterized by nearly degenerate electronic ground states such as MCO, M(CO) 2 , and M(CO) 3 , or transition metal carbonyls with coordination numbers greater than six. Density functional theory (DFT) methods as well as ab initio approaches are necessary to study these complicated electronic problems. Here, the field of polynuclear transition metal carbonyls is limited to binuclear complexes, studied extensively by DFT owing to the size of the molecules characterized by numerous geometrical structures with terminal or bridged CO and the possibility for metal–metal multiple bonds. This is illustrated by a detailed study of binuclear vanadium carbonyls V 2 (CO) n ( n = 9–12) coexisting in singlet as well as in triplet electronic configurations. Even if binuclear transition metal carbonyls are a source of interesting photochemistry, extensively investigated experimentally, only a few theoretical studies are devoted to this aspect. The world of mixed ligand transition metal carbonyls is vast and the number of problems to be solved is unlimited. One important part concerns the electronic ground state reactivity that can be studied by routine calculations based on the determination of reaction pathway energetics, transition states, and intermediates structures. The discovery of new catalysts is another facet illustrated by the study of the bonding capabilities of various ligands, which are isolobal analogs of CO. In the same manner, DFT calculations allow the prediction of new possible structures isoelectronic to well‐known homoleptic binuclear iron and manganese carbonyls. The richness of the photophysics and photochemistry of mixed ligand transition metal carbonyls makes them an inexhaustible subject for investigation including the assignment of featureless absorption spectra, the modeling of elementary steps that contribute to the observed photoreactivity, or the determination of the complete structure of electronic excited states. Transition metal carbonyls possessing low‐lying metal‐to‐ligand‐charge‐transfer states are fascinating in the diversity of processes generated by light absorption in the UV‐vis energy domain such as ultrafast dissociation of CO (∼100 fs), luminescence, electron transfer, or isomerization of selective ligands.

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Binding energy of chromium hexacarbonyl. 2. Revisited with correlation effects

Cited by 24 publications

References 3 publications

A quantum chemical calculation on Fe(CO)₅ revealing the operation of the Dewar–Chatt–Duncanson model

A quantum chemical calculation on Fe(CO)₅ revealing the operation of the Dewar–Chatt–Duncanson model

Ethylene coordination, insertion, and chain transfer at a cationic aluminum center: A comparative study withAb Initio correlated level and density functional methods

Electronic Structure Calculations: Metal Carbonyls

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Binding energy of chromium hexacarbonyl. 2. Revisited with correlation effects

Cited by 24 publications

References 3 publications

A quantum chemical calculation on Fe(CO)5 revealing the operation of the Dewar–Chatt–Duncanson model

A quantum chemical calculation on Fe(CO)5 revealing the operation of the Dewar–Chatt–Duncanson model

Ethylene coordination, insertion, and chain transfer at a cationic aluminum center: A comparative study withAb Initio correlated level and density functional methods

Electronic Structure Calculations: Metal Carbonyls

Contact Info

Product

Resources

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A quantum chemical calculation on Fe(CO)₅ revealing the operation of the Dewar–Chatt–Duncanson model

A quantum chemical calculation on Fe(CO)₅ revealing the operation of the Dewar–Chatt–Duncanson model