On the Dewar–Chatt–Duncanson Model for Catalytic Gold(I) Complexes

Salvi, Nicola; Belpassi, Leonardo; Tarantelli, Francesco

doi:10.1002/chem.201000608

Cited by 98 publications

(130 citation statements)

References 63 publications

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“…To study the presence of a CT component in these systems, we analyzed the electron density changes due to the interaction between CCl 4 (CF 4 ) and the Ngs by means of the charge displacement function (CDF), 100 which we have successfully used to study intermolecular weak interactions 48,50,[52][53][54][55]101,102 and chemical bonding in several diverse contexts. [103][104][105][106] …”

Section: A Computational Detailsmentioning

confidence: 99%

“…To investigate the occurrence of CT in the Ng-CCl 4 and Ng-CF 4 , including its radial dependence and stereo specificity, we exploited the CDF, recently employed with success to study the chemical bond in several contexts, [103][104][105][106] including weak intermolecular hydrogen bonds. 50,54,55 CDF offers a broad perspective for an assessment of the CT occurrence, free of any charge decomposition scheme.…”

Section: Ct Effectsmentioning

confidence: 99%

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Catching the role of anisotropic electronic distribution and charge transfer in halogen bonded complexes of noble gases

Bartocci

Belpassi

Cappelletti

et al. 2015

The Journal of Chemical Physics

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The systems studied in this work are gas-phase weakly bound adducts of the noble-gas (Ng) atoms with CCl4 and CF4. Their investigation was motivated by the widespread current interest for the intermolecular halogen bonding (XB), a structural motif recognized to play a role in fields ranging from elementary processes to biochemistry. The simulation of the static and dynamic behaviors of complex systems featuring XB requires the formulation of reliable and accurate model potentials, whose development relies on the detailed characterization of strength and nature of the interactions occurring in simple exemplary halogenated systems. We thus selected the prototypical Ng-CCl4 and Ng-CF4 and performed high-resolution molecular beam scattering experiments to measure the absolute scale of their intermolecular potentials, with high sensitivity. In general, we expected to probe typical van der Waals interactions, consisting of a combination of size (exchange) repulsion with dispersion/induction attraction. For the He/Ne-CF4, the analysis of the glory quantum interference pattern, observable in the velocity dependence of the integral cross section, confirmed indeed this expectation. On the other hand, for the He/Ne/Ar-CCl4, the scattering data unravelled much deeper potential wells, particularly for certain configurations of the interacting partners. The experimental data can be properly reproduced only including a shifting of the repulsive wall at shorter distances, accompanied by an increased role of the dispersion attraction, and an additional short-range stabilization component. To put these findings on a firmer ground, we performed, for selected geometries of the interacting complexes, accurate theoretical calculations aimed to evaluate the intermolecular interaction and the effects of the complex formation on the electron charge density of the constituting moieties. It was thus ascertained that the adjustments of the potential suggested by the analysis of the experiments actually reflect two chemically meaningful contributions, namely, a stabilizing interaction arising from the anisotropy of the charge distribution around the Cl atom in CCl4 and a stereospecific electron transfer that occurs at the intermolecular distances mainly probed by the experiments. Our model calculations suggest that the largest effect is for the vertex geometry of CCl4 while other geometries appear to play a minor to negligible role.

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Section: A Computational Detailsmentioning

confidence: 99%

Section: Ct Effectsmentioning

confidence: 99%

Catching the role of anisotropic electronic distribution and charge transfer in halogen bonded complexes of noble gases

Bartocci

Belpassi

Cappelletti

et al. 2015

The Journal of Chemical Physics

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“…The CDF is the exact definition of the amount of electronic charge which, upon formation of the complex, is displaced from left to right (the direction of decreasing z) across the plane perpendicular to the axis at point z. As previously demonstrated, [21,22] for suitably symmetric complexes and fragments, D1, and consequently Dq(z), can be decomposed into additive symmetry components which can be readily identified with the DCD components of the bond.In the present case, in order to separate the components, it is sufficient that the complex presents a symmetry plane perpendicular to the C À C bond of ethyne through its midpoint. All systems considered in this work have this C s symmetry.…”

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confidence: 99%

Disentanglement of Donation and Back‐Donation Effects on Experimental Observables: A Case Study of Gold–Ethyne Complexes

2013

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The Dewar-Chatt-Duncanson (DCD) model [1][2][3] was introduced more than 60 years ago to describe the h 2 coordination of ethene to a coinage-metal atom. It gives a formally simple picture of the bond between an unsaturated substrate (S) and a transition metal (M), which involves the donation of p electrons from the substrate to empty ds orbitals of the metal (S!M) and the back donation from filled dp orbitals of the metal to empty substrate orbitals of the proper symmetry (M!S). In unsaturated organic systems, these empty orbitals have typically a p* anti-bonding character and their population tends to weaken the CÀC bond, but a reverse effect may also be observed if the empty orbitals have a bonding character, as recently observed. [4][5][6] The DCD model enjoys enormous popularity among chemists, as it represents the standard framework in which to analyze the electronic properties of ligands and metal fragments, especially with a view of rationalizing and controlling the activation of substrates in catalyzed chemical reactions. It appears also appropriate for the captodative description of the carbon bond. [7] Despite the fact that the DCD model is so well accepted, the assessment of the relative importance of the donation and back-donation contributions to the bond is often ambiguous and controversial. [8][9][10][11][12][13] The components of the DCD model are quantum-mechanically not well defined [14] and, while conclusions are commonly drawn from indirect experimental clues, they may be unreliable because no rigorous quantitative relationship, of either theoretical or empirical nature, has ever been established between observed properties and the DCD bond components. In fact, even just proving that the relative extent of donation and back donation can at all be extracted from experiments would be a highly desirable feat. Herein, we demonstrate that the DCD components can be effectively disentangled, and in principle quantitatively revealed, by measuring simple experimental observables. As a prototype case study we consider the bond between gold and ethyne.Such coordination systems have received increasing attention in the recent impetuous development of novel homogeneousphase catalytic systems for alkyne activation. [15][16][17][18][19] Our analysis, which builds on a clear-cut quantitative definition of the DCD components, aims, at first, to show how donation and back donation in [Au 3 -ethyne] + correlate with simple observables, the bending of the C À C À H moiety and the redshift of the CÀC stretching frequency of ethyne. Having established this correlation, we then show that it is surprisingly accurate for a large number of compounds in which ethyne interacts with other metal substrates.As mentioned above, the key component of our analysis is a satisfactory and objective definition of the donation and back-donation charges. This can be obtained starting from the charge-displacement function (CDF): [20] DqðzÞ ¼where D1 is the difference between the electron density of a complex and that of its non-inter...

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“…The slightly more pronounced electron accumulation at the C1 site, compared with C2, is entirely consistent with the observed larger 13 C NMR shielding (Table 1). It is important to note that the AueC distance is a crucial factor for the modulation of the nature of the bond in this type of gold(I)ealkene (alkyne) complexes [31]. In particular, the metal-to-substrate p-back-donation component of the DewareChatteDuncanson model is most sensitive to the substrate distortion and its distance from gold(I).…”

Section: Synthesis and Intramolecular Characterization Of The Complexesmentioning

confidence: 99%

Ion pairing in NHC gold(I) olefin complexes: A combined experimental/theoretical study

Salvi

Belpassi

Zuccaccia

et al. 2010

Journal of Organometallic Chemistry

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On the Dewar–Chatt–Duncanson Model for Catalytic Gold(I) Complexes

Cited by 98 publications

References 63 publications

Catching the role of anisotropic electronic distribution and charge transfer in halogen bonded complexes of noble gases

Catching the role of anisotropic electronic distribution and charge transfer in halogen bonded complexes of noble gases

Disentanglement of Donation and Back‐Donation Effects on Experimental Observables: A Case Study of Gold–Ethyne Complexes

Ion pairing in NHC gold(I) olefin complexes: A combined experimental/theoretical study

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