An endohedral metallocarbohedrene C@Ti8C12

Lou, L.; Nordlander, Peter

doi:10.1016/0009-2614(94)00592-3

Cited by 19 publications

(33 citation statements)

References 22 publications

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“…This type of double numerical basis 15 has been used previously for clusters involving 3d transition metals and carbon and has shown to yield very satisfactory results for these kinds of systems. 16 The calculated total energy ͑presented as the relative energy between different structures for each cluster͒, the population on the Fe 3d/4s orbitals based on a Mulliken analysis, and the bond lengths in each structure are listed in Table I. Both the linear and two-dimensional structures are obtained by minimizing the total energy using analytical gradient methods, with no symmetry constraints on the displacements of the nuclei.…”

Section: Density Functional Calculationsmentioning

confidence: 99%

FeCn− and FeCnH− (n=3,4): A photoelectron spectroscopic and density functional study

Fan

Lou

Wang

1995

The Journal of Chemical Physics

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Photoelectron spectra of the title molecules are reported at 3.49 eV photon energy. Vibrational structures are resolved in the spectra of FeC−3 and FeC3H−. The FeC−4 spectrum is unusually broad, indicating a large equilibrium geometry change from the anion to the neutral states. The FeC4H− spectrum exhibits a single strong feature. Theoretical studies using the density functional theory are carried out to determine the structures and bonding of these clusters. All the molecules in the anion ground states are found to be linear with the Fe atom bonded at one end. The Fe and C bonding involves strong Fe 4s and C sp interactions as well as considerable Fe 3d and C π interactions. The n=3 species can be best characterized by cumulenic types of bonding with FeC3H also having an acetylenic isomer. The n=4 species in the linear structures can be approximately described by diacetylenic types of bonding. Mulliken charge analyses indicate that the extra charge in all the anions enters mainly into the Fe 4s antibonding orbital, in agreement with the assignment that the threshold detachment takes place from the σ* orbital mainly between the Fe and C atoms. The vibrational structure resolved in the FeC−3 spectrum yields a Fe–C stretching frequency of 700 (150) cm−1 for the first excited state of FeC3, in agreement with the Fe–C multiple bonding character.

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Section: Density Functional Calculationsmentioning

confidence: 99%

FeCn− and FeCnH− (n=3,4): A photoelectron spectroscopic and density functional study

Fan

Lou

Wang

1995

The Journal of Chemical Physics

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“…Castleman and co-workers have proposed a pentagonal dodecahedron structure with T h symmetry for the M 8 C 12 cluster, which is consistent with the results of saturation chemisorption studies 5 and ion chromatography experiments. 16 However, theoretical calculations indicate that other structures (T d or D 2d symmetry) slightly distorted from the T h cage are more likely, [17][18][19][20][21][22][23][24][25][26][27][28][29][30][31] and these structures are also supported by chemisorption experiments. 32 In spite of the intensive research on the metcars, the structure and bonding of these unique clusters are still not well understood.…”

Section: Introductionmentioning

confidence: 99%

Density Functional Study on the Structures and Energies of the Ti₂C₂Cluster

Sumathi

Hendrickx

1999

J. Phys. Chem. A

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The structures and energies of the binary dititanium dicarbide, Ti2C2, in the lowest singlet, triplet, and quintet states have been investigated by density functional theory using the hybrid B3LYP functionals. Geometries and frequencies for a number of isomeric structures are presented at the B3LYP level. A rhombic structure with a transannular C−C bond (VI) is found to be the global Ti2C2 minimum. The other four-membered planar ring structures (VII and VIII) derived from the two-fold addition of carbon to the Ti−Ti or the Ti−C bond of the cyclic (C 2 v ) Ti2C are characterized as higher energy local minima. A linear structure (I) with terminal titanium atoms is found to be a higher energy minimum in its singlet, triplet, and quintet potential energy surfaces (PES) and has a bonding characteristic of a cumulene-like valence structure. Besides, a unique nonplanar C 2 v structure, which has not been obtained in the isovalence electronic Si2C2 and SiC3 systems, has been identified as a minimum. Cyclic structures are energetically favored over the linear structures. A comparison with the tetra-atomic group IVA silicon−carbon clusters is given, where appropriate.

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“…Second , the reaction of polar molecules with Ti 8 C 12 and V 8 C 12 results in the adsorption of upto eight molecules, which signifies that all the eight metal sites are equivalent by coordination and also that the regular dodecahedron structure is among the five platonic solids, all of which are very well-known abundant stable structures, often preferred by nature. However, theoretical calculations showed the possibility of two different structures which are of D 2 d and T d symmetry, and they were found to be lower in energy than the T h symmetric structure proposed earlier. − Detailed investigations in this regard soon established the fact that the theoretical calculations are indeed correct, and the distorted T d structure is confirmed to be the ground state geometry, later verified by experiments …”

Section: Introductionmentioning

confidence: 83%

“…The initial guess geometry of tetrahedral Nb 8 C 12 is taken from the T d symmetric metcar structure reported in the earlier literature. − The neutral and the cationic structures of Nb–metcar are optimized by assigning different spin multiplicities using both M06-2X and B3LYP functional using Triple Zeta Valence Plus Polarization (TZVP) basis for “C” atoms and LANL2DZ-ECP basis for niobium. It is observed that with both the functionals, the neutral and cationic Nb 8 C 12 clusters with minimum spin multiplicity are lowest in energy (see Supporting Information).…”

Section: Computational Detailsmentioning

confidence: 99%

Mechanistic Investigation of the Carbon–Iodine Bond Activation on the Niobium–Carbon Cluster

2017

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The activation process of carbon–iodine (C–I) bond on neutral and cationic niobium metcars (Nb 8 C 12 ) is investigated using density functional theory and related computational techniques. Metallocarbohedrenes or metcars are a class of stable metal–carbide clusters of specific stoichiometry and of great interest to cluster chemists since their first discovery. The detailed reaction mechanism along with the overall energy profile of the C–I dissociation reaction on niobium metcar and its cations is presented in this paper. The tunneling-corrected rate constants and their related reaction parameters such as the pre-exponential factor are also included alongside. The major differences between the reaction mechanism of the neutral and cationic metcars are also highlighted as well. Despite the available experimental results, the C–I bond dissociation on metcars has remained an unexplored problem in the theoretical and computational domains. Thus, the present investigation can fill in the gap and may also provide new insights provoking further developments in cluster and materials chemistry in future.

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An endohedral metallocarbohedrene C@Ti8C12

Cited by 19 publications

References 22 publications

FeCn− and FeCnH− (n=3,4): A photoelectron spectroscopic and density functional study

FeCn− and FeCnH− (n=3,4): A photoelectron spectroscopic and density functional study

Density Functional Study on the Structures and Energies of the Ti₂C₂Cluster

Mechanistic Investigation of the Carbon–Iodine Bond Activation on the Niobium–Carbon Cluster

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An endohedral metallocarbohedrene C@Ti8C12

Cited by 19 publications

References 22 publications

FeCn− and FeCnH− (n=3,4): A photoelectron spectroscopic and density functional study

FeCn− and FeCnH− (n=3,4): A photoelectron spectroscopic and density functional study

Density Functional Study on the Structures and Energies of the Ti2C2Cluster

Mechanistic Investigation of the Carbon–Iodine Bond Activation on the Niobium–Carbon Cluster

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Density Functional Study on the Structures and Energies of the Ti₂C₂Cluster