σ‐Conjugation and σ‐Aromaticity

Dewar, Michael J. S.

doi:10.1002/bscb.19790881201

Cited by 313 publications

(354 citation statements)

References 22 publications

(1 reference statement)

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“…2b and 2c). Consequently, the interaction between the Pt atom and the PAH molecule can be characterized according to the Dewar-Chatt-Duncanson model [107][108][109] .…”

Section: -12 |mentioning

confidence: 99%

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Structural and electronic properties of the Pt_n–PAH complex (n = 1, 2) from density functional calculations

Mahmoodinia

Ebadi

Åstrand

et al. 2014

Phys. Chem. Chem. Phys.

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A detailed density functional study of the Pt atom and Pt dimer adsorption on a polyaromatic hydrocarbon (PAH) is presented. The preferred adsorption site for a Pt atom is confirmed to be the bridge site. Upon adsorption of a single Pt atom, however, it is found here that the electronic ground state changes from the triplet state (5d 9 6s 1 configuration) to the closed-shell singlet state (5d 10 6s 0 configuration), which consequently will affect the catalytic activity of Pt when single Pt atoms bind to a carbon surface. The preferred adsorption site for the Pt dimer in the upright configuration is the hollow site. In contrast to the adsorption of a single Pt atom, the formation of a Pt-C bond in the adsorption of a Pt dimer is not accompanied by a change in the spin state, so the most stable electronic state is still the triplet state. While the atomic charge on the Pt atoms and dimers (in parallel configuration) in the Pt n /PAH complex is positive, a negative charge is found on the upper Pt atom for the upright configuration, indicating that single layers of Pt atoms will have a different catalytic activity as compared to Pt clusters on a carbon surface. Comparing the Pt-C bond length and the charge transfer on different sites, the magnitude of the charge transfer decreases with bond elongation, indicating that the catalytic activity of the Pt atom and dimer can be changed by modifying its chemical surroundings. The adsorption energy for the Pt dimer on a PAH surface is larger than for two individual Pt atoms on the surface indicating that aggregation of Pt atoms on the PAH surface is favorable.

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“…2b and 2c). Consequently, the interaction between the Pt atom and the PAH molecule can be characterized according to the Dewar-Chatt-Duncanson model [107][108][109] .…”

Section: -12 |mentioning

confidence: 99%

“…The donation and backdonation charge density between the Pt atoms and the PAH molecule is illustrated in these figures. Again, the interaction between the Pt atom and dimer with the PAH molecule can be characterized by the Dewar-Chatt-Duncanson model [107][108][109] .…”

Section: Pt Dimer On the Pah Surfacementioning

confidence: 99%

Structural and electronic properties of the Pt_n–PAH complex (n = 1, 2) from density functional calculations

Mahmoodinia

Ebadi

Åstrand

et al. 2014

Phys. Chem. Chem. Phys.

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“…Already classical view on binding and activation of ligands with multiple bonds in complexes with transition-metal cations ascribed them to two main electronic contributions: donation and backdonation processes [24,25]. On the other hand, it was suggested, after analyzing atomic population changes upon ligand adsorption on a bare cation versus the cation embedded in a model environment that the unusual catalytic activity of transition-metal exchanged zeolites should be due to the activation of the transition-metal ion by the zeolite framework which functions as a specific ligand.…”

Section: Introductionmentioning

confidence: 99%

On the nature of spin- and orbital-resolved Cu+–NO charge transfer in the gas phase and at Cu(I) sites in zeolites

et al. 2012

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Electronic factors essential for NO activation by Cu(I) sites in zeolites are investigated within spin-resolved analysis of electron transfer channels (natural orbitals for chemical valence). NOCV analysis is performed for three DFT-optimized models of Cu(I)-NO site in ZSM-5: [CuNO] ? , (T1)CuNO, and (M7)CuNO. NO as a non-innocent, openshell ligand reveals significant differences between independent deformation density components for a and b spins. Four distinct components are identified: (i) unpaired electron donation from NO p k * antibonding orbital to Cu s,d ; (ii) backdonation from copper d yz to p \ * antibonding orbital; (iii) donation from occupied p k and Cu d xz to bonding region, and (iv) donation from nitrogen lone-pair to Cu s,d . Channel (i), corresponding to one-electron bond, shows-up solely for spin majority and is effective only in the interaction of NO with naked Cu ? . Channel (ii) dominates for models b and c: it strongly activates NO bond by populating antibonding p* orbital and weakens the N-O bond in contrast to channel (i), depopulating the antibonding orbital and strengthening N-O bond. This picture perfectly agrees with IR experiment: interaction with naked Cu ? imposes small blue-shift of NO stretching frequency while it becomes strongly red-shifted for Cu(I) site in ZSM-5 due to enhanced backdonation.

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“…93,94 That is, in both cases there generally exists one -type MO that is a linear combination of Proposed mechanisms for the hydrolysis of 1.…”

mentioning

confidence: 99%

Phospha-Fischer Carbenes: Synthesis, Structure, Bonding, and Reactions of Pd(0)− and Pt(0)−Phosphenium Complexes

et al. 2009

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σ‐Conjugation and σ‐Aromaticity

Cited by 313 publications

References 22 publications

Structural and electronic properties of the Pt_n–PAH complex (n = 1, 2) from density functional calculations

Structural and electronic properties of the Pt_n–PAH complex (n = 1, 2) from density functional calculations

On the nature of spin- and orbital-resolved Cu+–NO charge transfer in the gas phase and at Cu(I) sites in zeolites

Phospha-Fischer Carbenes: Synthesis, Structure, Bonding, and Reactions of Pd(0)− and Pt(0)−Phosphenium Complexes

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σ‐Conjugation and σ‐Aromaticity

Cited by 313 publications

References 22 publications

Structural and electronic properties of the Ptn–PAH complex (n = 1, 2) from density functional calculations

Structural and electronic properties of the Ptn–PAH complex (n = 1, 2) from density functional calculations

On the nature of spin- and orbital-resolved Cu+–NO charge transfer in the gas phase and at Cu(I) sites in zeolites

Phospha-Fischer Carbenes: Synthesis, Structure, Bonding, and Reactions of Pd(0)− and Pt(0)−Phosphenium Complexes

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Structural and electronic properties of the Pt_n–PAH complex (n = 1, 2) from density functional calculations

Structural and electronic properties of the Pt_n–PAH complex (n = 1, 2) from density functional calculations