Transition‐Metal Atoms and Dimers

Salahub, Dennis R.

doi:10.1002/9780470142943.ch8

Cited by 128 publications

(9 citation statements)

References 332 publications

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“…In this short prospective we have no aim to provide a complete overview of all the theoretical efforts that have been devoted to the understanding of the bonding in Cr-Cr complexes. Several excellent reviews exist on this topic [21,27,[32][33][34][35] and the reader is invited to consult these Letters as well as the references therein. Instead, we now present an account of the important steps in the theoretical development of the description of the multiply bonded Cr-Cr species over the last three decades.…”

Section: A Historical Overview Of the Theoretical Methodsmentioning

confidence: 99%

Analysing the chromium–chromium multiple bonds using multiconfigurational quantum chemistry

Brynda

Gagliardi

Roos³

2009

Chemical Physics Letters

112

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a b s t r a c tThis Letter discusses the nature of the chemical bond between two chromium atoms in different di-chromium complexes with the metal atoms in different oxidation states. Starting with the Cr diatom, with its formally sextuple bond and oxidation number zero, we proceed to analyse the bonding in some Cr(I)-Cr(I) XCrCrX complexes with X varying from F, to Phenyl, and Aryl. The bond distance in these complexes varies over a large range: 1.65-1.83 Å and we suggest explanations for these variations. A number of dichromium complexes with bond distances around or shorter than 1.80 Å have recently been synthesized and we study one of these complexes, Cr 2 (diazadiene) 2 and show how the Cr-Cr bond order is related to the oxidation number and the ligand bonding, factors that are all involved in the determination of the short Cr-Cr bond length: 1.80 Å. The discussion is based on the use of multiconfigurational wave functions, which give a qualitatively correct description of the electronic structure in these multiply bonded systems.

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Section: A Historical Overview Of the Theoretical Methodsmentioning

confidence: 99%

Analysing the chromium–chromium multiple bonds using multiconfigurational quantum chemistry

Brynda

Gagliardi

Roos³

2009

Chemical Physics Letters

112

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“…38−41 In contrast, LDA is well-known to overestimate adsorption energies when interactions are stronger than πdispersion. 42 In fact, DFT-LDA can qualitatively and quantitatively give an accurate description of the electronic structure of graphitic and carbon nanotube structures where the band structures are dominated by the chemistry of sp 2 orbitals and do not significantly depend on van der Waals forces. 40,43,44 We have previously shown 45 that adsorption energy of benzene on graphene, a pure dispersive system, is clearly underestimated at the LDA (0.20 eV) level, but the value obtained at the PBE+D level (0.5 eV) is in excellent agreement with the experimental value (0.5 eV).…”

Section: Computational Detailsmentioning

confidence: 99%

Electronic Properties of Self-Assembled Trimesic Acid Monolayer on Graphene

Shayeganfar

Rochefort

2014

Langmuir

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The adsorption of trimesic acid (TMA) on a graphene surface has been studied with density functional theory. By considering the adsorption of a single TMA molecule on different sites on graphene, we have been able to perform a detailed analysis of the equilibrium geometry, charge transfer, electronic properties in terms of density of states and band structure, and finally scanning tunneling microscopy simulations on those simple systems. The results for isolated adsorption were then compared to the behavior of the TMA unit within two different self-assembled monolayers. Our results indicate that structural deformations of TMA may significantly contribute to the magnitude of p-doping and band gap opening in graphene. The formation of a hydrogen bonding network within the assembly improves the stability of the adlayer, but its adhesion on graphene is significantly reduced. The magnitude of p-doping in graphene per TMA unit remains nearly constant from the isolated to the assembled systems, but the magnitude of the band gap opening appears to be strongly correlated with the breaking of symmetry of π-states of graphene by the TMA patterning on the surface. Our results suggest that polymorphism in self-assembled adlayers could be used to tune and control the electronic properties of graphene.

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“…This is evident from the large number of studies involving the same method for gas molecule adsorption in the literature. 17,18,[43][44][45][46][47] It should also be noted that local density approximation (LDA) overestimates the adsorption energy 48 for the weakly bound charge-transfer systems and hence, we believe that GGA is an appropriate choice for our calculations describing the interaction between the halogens and the nanocarbons.…”

Section: Computational Detailsmentioning

confidence: 99%

The interaction of halogen molecules with SWNTs and graphene

Ghosh¹,

Yamijala²,

Pati³

et al. 2012

RSC Adv.

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The interaction of halogen molecules of varying electron affinity, such as iodine monochloride (ICl), bromine (Br 2 ), iodine monobromide (IBr) and iodine (I 2 ) with single-walled carbon nanotubes (SWNTs) and graphene has been investigated in detail. Halogen doping of the two nanocarbons has been examined using Raman spectroscopy in conjunction with electronic absorption spectroscopy and extensive theoretical calculations. The halogen molecules, being electron withdrawing in nature, induce distinct changes in the electronic states of both the SWNTs and graphene, which manifests with a change in the spectroscopic signatures. Stiffening of the Raman G-bands of the nanocarbons upon treatment with the different halogen molecules and the emergence of new bands in the electronic absorption spectra, both point to the fact that the halogen molecules are involved in molecular charge-transfer with the nanocarbons. The experimental findings have been explained through density functional theory (DFT) calculations, which suggest that the extent of charge-transfer depends on the electron affinities of the different halogens, which determines the overall spectroscopic properties. The magnitude of the molecular charge-transfer between the halogens and the nanocarbons generally varies in the order ICl . Br 2 . IBr . I 2, which is consistent with the expected order of electron affinities.

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Transition‐Metal Atoms and Dimers

Cited by 128 publications

References 332 publications

Analysing the chromium–chromium multiple bonds using multiconfigurational quantum chemistry

Analysing the chromium–chromium multiple bonds using multiconfigurational quantum chemistry

Electronic Properties of Self-Assembled Trimesic Acid Monolayer on Graphene

The interaction of halogen molecules with SWNTs and graphene

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