The Molecular Structure of Gaseous Dibenzene Chromium (C6H6)2Cr.

Haaland, Arne; Blomstrand, Rolf; Reunanen, Matti; Kyyhkynen, Hertta; Hoffman, Ragnar A.; Westerdahl, Anders

doi:10.3891/acta.chem.scand.19-0041

Cited by 131 publications

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“…The structural rehybridization is known to be quite small in the bis(benzene)Cr molecule. 28 Similarly, the Cr atom does not cause remarkable changes in the different junctions investi- 39 This value is remarkably close to that of the present study. Larger linker atoms also move the neighboring carbon atoms away from the TM atom and the average displacement of the six nearest-neighbor carbon atoms is 0.15 Å in the case of a molybdenum or tungsten linker atom.…”

Section: A Structure Of the Tm-atom-cnt Junctionssupporting

confidence: 80%

Enhancing conductivity of metallic carbon nanotube networks by transition metal adsorption

Ketolainen

Havu

Puska

2015

The Journal of Chemical Physics

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The conductivity of carbon nanotube thin films is mainly determined by carbon nanotube junctions, the resistance of which can be reduced by several different methods. We investigate electronic transport through carbon nanotube junctions in a four-terminal configuration, where two metallic single-wall carbon nanotubes are linked by a group 6 transition metal atom. The transport calculations are based on the Green’s function method combined with the density-functional theory. The transition metal atom is found to enhance the transport through the junction near the Fermi level. However, the size of the nanotube affects the improvement in the conductivity. The enhancement is related to the hybridization of chromium and carbon atom orbitals, which is clearly reflected in the character of eigenstates near the Fermi level. The effects of chromium atoms and precursor molecules remaining adsorbed on the nanotubes outside the junctions are also examined.

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Section: A Structure Of the Tm-atom-cnt Junctionssupporting

confidence: 80%

Enhancing conductivity of metallic carbon nanotube networks by transition metal adsorption

Ketolainen

Havu

Puska

2015

The Journal of Chemical Physics

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“…In agreement with studies using various experimental techniques (X-ray, IR spectroscopy, gas-phase electron diffraction) [24][25][26] as well as previous quantum-chemical calculations, [21,26,27] our calculations predict a D 6h -symmetric structure for (h 6 -C 6 H 6 ) 2 Cr (12 b; Figure 1, Table 1). In 12 b, the distance between the metal atom and the center of each FULL PAPER basal cycle (1.646 ) is the shortest among the metallocenes considered thus far (1.721 for 10 b and 1.684 for 11 b) and the HOMO-LUMO energy gap (3.99 eV) is smaller than that for either 10 b (4.23 eV) or 11 b (5.14 eV).…”

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confidence: 76%

Sandwich Compounds of Transition Metals with Cyclopolyenes and Isolobal Boron Analogues

Gribanova

Starikov

Minyaev

et al. 2010

Chemistry A European J

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A series of sandwich compounds of transition metals (M=Ni, Fe, Cr) with cyclic hydrocarbon (M(CH)(n)) and borane (M(BH(2))(n)), ligands (including mixed hydrocarbon/borane sandwiches) has been studied using density functional theory (B3LYP/6-311+G(df,p)). Multicenter bonding between the central metal atom and basal cycloborane rings provides stabilization to planar cycloborane species. Large negative NICS values allude to aromatic character in the cycloboranes similar to the analogous cyclic hydrocarbons. The ability of cycloborane sandwiches to stabilize attached carbocations, radicals and carbanions is also assessed.

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“…Part of the interest in this complex arose from discussions on the symmetry of the benzene ring in chromium dibenzene. After some controversy the symmetry was determined to be D6h (crystal structure at 100°K by Keulen & Jellinek, 1966; electron diffraction in gas phase by Haaland, 1965; infrared spectrum in gas phase by Ngai, Stafford & Schfifer, 1969; thermodynamic study by Andrews, Westrum & Bjerrum, 1969). The symmetry of the isolated benzene chromium tricarbonyl molecule is C3v but the room-temperature study by Bailey & Dahl (1965a) did not show any evidence for a distortion of the benzene ring from D6h symmetry.…”

Section: Introductionmentioning

confidence: 99%

Electronic structure of benzene chromium tricarbonyl by X-ray and neutron diffraction at 78 K

Rees¹,

Coppens²

1973

Acta Crystallogr Sect B

155

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The crystal structure of C6H6Cr(CO)3 has been studied at 78 °K by both X-ray and neutron diffraction. The studies indicate a lowering of the benzene-ring symmetry to C3v. The C-C bonds in the ring alternate in length, the shortest bonds being trans to the carbonyl groups. The average difference is 0-017 (2)/~,. The observed bond lengths correlate well with electron overlap populations obtained in semi-empirical molecular orbital calculations. The neutron results show the hydrogen atom to be displaced by an average of 0.03 A from the plane of the benzene ring in a direction towards the chromium atom. X-N maps show large residual density features near the chromium nucleus, which are to be confirmed by further studies on related compounds. Other residual peaks correspond to the overlap density in the Cr-C, C-C, C-O and C-H bonds and to the lone-pair electrons on the oxygen atoms. The Cr-C(O) bond peaks are closer to the carbon atom, in agreement with theoretical predictions. This is the first combined X-ray and neutron diffraction study of a compound containing third-row atoms, and it is concluded that the bonding in transition metal complexes can now be studied by this technique. A spherical charge refinement of the X-ray data did not lead to satisfactory results. This is partly due to the lack of an appropriate X-ray form factor for chromium.

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The Molecular Structure of Gaseous Dibenzene Chromium (C6H6)2Cr.

Cited by 131 publications

References 0 publications

Enhancing conductivity of metallic carbon nanotube networks by transition metal adsorption

Enhancing conductivity of metallic carbon nanotube networks by transition metal adsorption

Sandwich Compounds of Transition Metals with Cyclopolyenes and Isolobal Boron Analogues

Electronic structure of benzene chromium tricarbonyl by X-ray and neutron diffraction at 78 K

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