The essential role of charge-shift bonding in hypervalent prototype XeF2

Braı̈da, Benoı̂t; Hiberty, Philippe C.

doi:10.1038/nchem.1619

Cited by 103 publications

(99 citation statements)

References 42 publications

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“…In a way, the scenario of this work upends earlier criteria for the viability of hypervalence, by Braïda and Hiberty (34,35) and Braïda et al (36) within valence-bond theory (34)(35)(36) and by Bickelhaupt and coworkers within MO theory (37). These models relate increasing viability of hypervalence to decreasing ionization potential and increasing atomic radius of the central element.…”

Section: Discussionsupporting

confidence: 72%

Eight-coordinate fluoride in a silicate double-four-ring

Goesten

Hoffmann

Bickelhaupt

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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Fluoride, nature's smallest anion, is capable of covalently coordinating to eight silicon atoms. The setting is a simple and common motif in zeolite chemistry: the box-shaped silicate double-four-ring (D4R). Fluoride seeks its center. It is the strain of box deformation that keeps fluoride in the middle of the box, and freezes what would be a transition state in its absence. Hypervalent bonding ensues. Fluoride's compactness works to its advantage in stabilizing the cage; chloride, bromide, and iodide do not bring about stabilization due to greater steric repulsion with the box frame. The combination of strain and hypervalent bonding, and the way they work in concert to yield this unusual case of multiple hypervalence, has potential for extension to a broader range of solidstate compounds.hat is the maximum number of atoms to which a maingroup element may bond? Four, one would normally think. But, hypervalence and delocalized bonding enlarge the upper range--no one bats an eyelid at silicon binding 6 ligands, and there exist cases of arguably 10-coordinate Si (1, 2). Much thinking on high coordination focuses on atomic or ionic radii, and packing considerations. Or, one can approach the problem from a quantum-chemical perspective. In this paper, we follow the latter course, and operate at the crossing point between molecular and extended systems. We explore how the upper bound for coordination number is determined by attractive and repulsive forces, adding in a factor of strain, associated with deforming a molecular cage that entraps an element in its center.The stage for this work is set by a simple and common motif in catalysis and separation: the silicate double-four-ring (D4R), one of the archetypal building blocks in large-pore zeolites. By use of relativistic density-functional theory (DFT) calculations and Kohn-Sham molecular orbital theory (3-6), we will see that within this box-like environment, fluoride coordinates, actually binds, to eight silicon atoms.

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Section: Discussionsupporting

confidence: 72%

Eight-coordinate fluoride in a silicate double-four-ring

Goesten

Hoffmann

Bickelhaupt

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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“…39 XeF 2 is a typical hypervalent molecule, which can be described through the Rundle-Pimentel 40 model, i.e. a three-center-four-electron molecular orbital diagram.…”

Section: V2 Hypervalency and Charge-shift Bondingmentioning

confidence: 99%

How valence bond theory can help you understand your (bio)chemical reaction

et al. 2015

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“…The VB-QMC wave function we utilize here consists of a VBSCF determinant part multiplied by a Jastrow function that is included to account for electronic correlation. The Jastrow function is the same as in previous studies [44][45][46] and includes explicit two-body electron-electron, electronnucleus, and also three-body electron-electron-nucleus terms. In this study, the energies of the N and V states are computed by optimizing simultaneously Jastrow parameters, VB structural coefficients, and, in some specified cases, also orbitals.…”

Section: The Vb-qmc Levelsmentioning

confidence: 99%

“…Very recently, a mixed valence bond/quantum Monte Carlo (VB-QMC) method has been proposed which managed to provide high accuracy while keeping the full interpretative capabilities of classical valence bond methods [44][45][46]. The VB-QMC wave function we utilize here consists of a VBSCF determinant part multiplied by a Jastrow function that is included to account for electronic correlation.…”

Section: The Vb-qmc Levelsmentioning

confidence: 99%

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The V state of ethylene: valence bond theory takes up the challenge

Zhang

Braı̈da

et al. 2014

Theor Chem Acc

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HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. Further improvement to 7.96/7.93 eV is achieved at the variational and diffusion Monte Carlo (MC) levels, respectively, VMC/DMC, using a Jastrow factor coupled with the same compact VB wave function. Furthermore, the measure of the spatial extension of the V state wave function, 19.14 a 0 2 , is in the range of accepted values obtained by large-scale state-of-the-art molecular orbitalbased methods. The r response to the fluctuations of the p electrons in the V state, known to be a crucial feature of the V state, is taken into account using the breathing orbital valence bond method, which allows the VB structures to have different sets of orbitals. Further valence bond calculations in a larger space of configurations, involving explicit participation of the r response, with 9 VB structures for the N state and 14 for the V state, confirm the results of the minimal structure set, yielding an N ? V transition energy of 7.97 eV and a spatial extension of 19.16 a 0 2 for the V state. Both types of valence bond calculations show that the V state of ethylene is not fully ionic as usually assumed, but involving also a symmetryadapted combination of VB structures each with asymmetric covalent p bonds. The latter VB structures have cumulated weights of 18-26 % and stabilize the V state by about 0.9 eV. It is further shown that these latter VB structures, rather than the commonly considered zwitterionic ones, are the ones responsible for the spatial extension of the V state, known to be ca. 50 % larger than the V state.Keywords Valence bond Á Quantum Monte Carlo Á V state of ethylene Á Breathing orbitals 1 Introduction

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The essential role of charge-shift bonding in hypervalent prototype XeF2

Cited by 103 publications

References 42 publications

Eight-coordinate fluoride in a silicate double-four-ring

Eight-coordinate fluoride in a silicate double-four-ring

How valence bond theory can help you understand your (bio)chemical reaction

The V state of ethylene: valence bond theory takes up the challenge

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