A DFT Study of the Interstitial Chemical Shifts in Main Group Element Centered Hexazirconium Halide Clusters

Shen, Jingyi; Hughbanks, Timothy

doi:10.1021/jp0368029

Cited by 4 publications

(5 citation statements)

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“…41 Recently, Shen and Hughbanks also described the qualitative inverse proportionality between the interstitial chemical shifts and the calculated energy gaps between pairs of Kohn-Sham orbitals in main group element centered hexazirconium halide clusters. 68 In this case it was deduced from symmetry arguments that the HLG was not an appropriate criterion. We will show in the fifth section with the help of accurately determined MO contributions that for complexes VI and VII, the HOMO itself does not contribute to J Pt -Tl in the unsolvated systems.…”

Section: Comparison Of the Optimized Complexes With The Single-crystamentioning

confidence: 99%

NMR properties of platinumthallium bonded complexes: analysis of relativistic density functional theory results

2004

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The metal NMR parameters of the complexes [(NC)(5)Pt-Tl(CN)(n)](n -) (n = 0-3, I-IV) and [(NC)(5)Pt-Tl-Pt(CN)(5)](3-) (V), as well as [{Pt(NO(3))(NH(3))(2)L(2)}Tl(NO(3))(2)(MeOH)] (VI) and [{Pt(NO(3))(NH(3))(2)L(2)}(2)Tl](+) (VII) with L = NHCO(t)Bu, were computationally investigated by relativistic density functional theory. Complexes I-V were previously studied by us. We briefly review the main findings here. Their spin-spin coupling constants are analyzed in terms of molecular orbital and fragment orbital contributions which demonstrate the various influences of the solvent and of the ligands on the extraordinarily large metal-metal coupling constants. Complexes VI and VII and various model systems were investigated in more detail. It is shown that the same computational model which performs best for I-V yields too large metal-metal coupling constants for VI and VII. The analysis shows that this is likely to be attributable to a strong sensitivity of the coupling constants to the rather small Pt 6s contributions in the occupied metal-metal sigma-bonding orbitals. Bulk solvent effects on the metal-metal couplings are sizeable and should be considered in the computational model. Both calculated and experimental Pt--Tl coupling constants for VI and VII are substantially larger than those for I-V, thereby representing the largest heteronuclear coupling constants known so far experimentally. Metal chemical shifts for VI and VII were also investigated. The computational results indicate that the choice of the Pt reference is rather problematic. Tl chemical shifts agree much better with experimental data.

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Section: Comparison Of the Optimized Complexes With The Single-crystamentioning

confidence: 99%

NMR properties of platinumthallium bonded complexes: analysis of relativistic density functional theory results

2004

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“…[11] By using the density functional theory, a quantitative extension of this work has established additional correlations between the interstitial chemical shifts and the electronic structure of such complexes. [12] However, previous analyses of the electronic structure of main group element centered octahedral gold clusters have highlighted the differences between the title complex and interstitial carbide complexes. [1,13] In particular, one should underline that the gold systems are thought to have radial CÀAu bonds and rather weak (aurophilic) interactions between the AuL ligands, whereas in the case of interstitial carbide complexes, strong metal-metal bonds stabilize the structures.…”

Section: Introductionmentioning

confidence: 97%

“…Other examples are the 13 C NMR chemical shifts of a series of interstitial carbides in transition-metal clusters. [3][4][5][6][7] It might thus be expected that the interstitial 13 C NMR chemical shift in 1 is very large in magnitude, either positive or negative depending on whether the chemical environment is similar to carbides or similar to clusters as WAu 12 .…”

Section: Introductionmentioning

confidence: 99%

The “Invisible” ¹³C NMR Chemical Shift of the Central Carbon Atom in [(Ph₃PAu)₆C]²⁺: A Theoretical Investigation

Guennic¹,

Neugebauer²,

Reiher³

et al. 2005

Chemistry A European J

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The experimental 13C NMR chemical shift of the central carbon atom in the octahedral [(Ph3PAu)6C]2+ cluster was investigated on the basis of relativistic density functional calculations. In order to arrive at independent model conclusions regarding the value of the chemical shift, a systematic study of the dependence of the cluster structure on the phosphine ligands, the chosen density functionals, and the basis set size was conducted. The best structures obtained were then used in the NMR calculations. Because of the cage-like cluster structure a pronounced deshielding of the central carbon nucleus could have been expected. However, upon comparison with the 13C NMR properties of the related complex [C{Au[P(C6H5)2(p-C6H4NMe2)]}6]2+, Schmidbaur et al. have assigned a signal at delta=135.2 ppm to the interstitial carbon atom. Our calculations confirm this value in the region of the aromatic carbon atoms of the triphenylphosphine ligands. The close-lying signals of the 108 phenyl carbon atoms can explain the difficulties of assigning them experimentally.

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“…Later density functional theory (DFT) and Hartree-Fock (HF) calculations established that the HOMO is metal-based and that the emission can be described as a metal-metal transition, contradicting a previous XR calculation, but description of the absorption excitations were not substantially changed. 27,35,37 In connection with our long-standing interest in polynuclear metal clusters, [38][39][40][41] this paper seeks to extend the study of [Re 6 S 8 ] 2+ clusters' electronic structure via timedependent density functional theory (TDDFT) calculations. We will examine the influence that the high negative charge borne by these clusters has on their predicted optical properties by comparing calculations on clusters in vacuo and in the solid state.…”

Section: Introductionmentioning

confidence: 99%

“…In connection with our long-standing interest in polynuclear metal clusters, − this paper seeks to extend the study of [Re 6 S 8 ] 2+ clusters' electronic structure via time-dependent density functional theory (TDDFT) calculations. We will examine the influence that the high negative charge borne by these clusters has on their predicted optical properties by comparing calculations on clusters in vacuo and in the solid state.…”

Section: Introductionmentioning

confidence: 99%

Electronic Transitions in [Re₆S₈X₆]⁴^- (X = Cl, Br, I): Results from Time-Dependent Density Functional Theory and Solid-State Calculations

Roy

Hughbanks

2006

Inorg. Chem.

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Relativistic time-dependent density functional theory (TDDFT) calculations were performed on the excited states of the [Re6S8X6](4-) (X = Cl, Br, I) series. For all members of the series, the lowest excited states in the spectra do not correspond to a ligand-to-metal (or ligand-to-cluster) excitation but rather a cluster-cluster transition from the HOMO e(g) to antibonding t(1u) orbitals with only a modest admixture of Re-X sigma* character. These results lead to a re-evaluation of the role of the axial ligand in these compounds. The calculated excitation energies reproduce the experimental absorption and emission spectra. This work also confirms previous TDDFT calculations on the emission energies. Results for discrete cluster ions are compared with those obtained from calculations in the solid state in Cs4[Re6S8X6].CsX (X = Cl, Br) and Cs4[Re6S8I6].2CsI. Significant differences are seen in the relatively higher energies of the antibonding t(1u) orbital in the solid-state case, and an inversion in the orbital character of the two allowed absorptions is calculated. The e(g) (HOMO)-to-a(2g) (LUMO) orbital energy differences corresponding to the emission transition are quite comparable for the solid state and discrete cluster calculations, and both overestimate the observed emission energy by the same margin.

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A DFT Study of the Interstitial Chemical Shifts in Main Group Element Centered Hexazirconium Halide Clusters

Cited by 4 publications

References 53 publications

NMR properties of platinumthallium bonded complexes: analysis of relativistic density functional theory results

NMR properties of platinumthallium bonded complexes: analysis of relativistic density functional theory results

The “Invisible” ¹³C NMR Chemical Shift of the Central Carbon Atom in [(Ph₃PAu)₆C]²⁺: A Theoretical Investigation

Electronic Transitions in [Re₆S₈X₆]⁴^- (X = Cl, Br, I): Results from Time-Dependent Density Functional Theory and Solid-State Calculations

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A DFT Study of the Interstitial Chemical Shifts in Main Group Element Centered Hexazirconium Halide Clusters

Cited by 4 publications

References 53 publications

NMR properties of platinumthallium bonded complexes: analysis of relativistic density functional theory results

NMR properties of platinumthallium bonded complexes: analysis of relativistic density functional theory results

The “Invisible” 13C NMR Chemical Shift of the Central Carbon Atom in [(Ph3PAu)6C]2+: A Theoretical Investigation

Electronic Transitions in [Re6S8X6]4- (X = Cl, Br, I): Results from Time-Dependent Density Functional Theory and Solid-State Calculations

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Product

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The “Invisible” ¹³C NMR Chemical Shift of the Central Carbon Atom in [(Ph₃PAu)₆C]²⁺: A Theoretical Investigation

Electronic Transitions in [Re₆S₈X₆]⁴^- (X = Cl, Br, I): Results from Time-Dependent Density Functional Theory and Solid-State Calculations