Four Decades of the Chemistry of Planar Hypercoordinate Compounds

Li, Yang; Ganz, Eric; Chen, Zhongfang; Wang, Zhi Xiang; Schleyer, Paul von Ragué

doi:10.1002/anie.201410407

Cited by 229 publications

(208 citation statements)

References 299 publications

(612 reference statements)

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“…A direct consequence of this model is that the 3c-4e bond is expected to be substantially weaker than the two-center two-electron (2c-2e) bond in a given hypervalent molecule. Even though there are various works showing that d-orbital contributions to hypervalent bonds (HVB) are minimal, many chemistry text books still make use of the idea of an extended octet and the formation of spd-hybrid orbitals to explain HVB [34]. There is a strong overlap between the concepts of fractional bond order, the 3c-4e bond, and the halogen bond (XB) in trihalides, which are considered prime examples of 3c-4e bonding, but also strong XB [35,36].…”

Section: Introductionmentioning

confidence: 99%

A Continuum from Halogen Bonds to Covalent Bonds: Where Do λ3 Iodanes Fit?

et al. 2019

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The intrinsic bonding nature of λ 3 -iodanes was investigated to determine where its hypervalent bonds fit along the spectrum between halogen bonding and covalent bonding. Density functional theory with an augmented Dunning valence triple zeta basis set ( ω B97X-D/aug-cc-pVTZ) coupled with vibrational spectroscopy was utilized to study a diverse set of 34 hypervalent iodine compounds. This level of theory was rationalized by comparing computational and experimental data for a small set of closely-related and well-studied iodine molecules and by a comparison with CCSD(T)/aug-cc-pVTZ results for a subset of the investigated iodine compounds. Axial bonds in λ 3 -iodanes fit between the three-center four-electron bond, as observed for the trihalide species IF 2 − and the covalent FI molecule. The equatorial bonds in λ 3 -iodanes are of a covalent nature. We explored how the equatorial ligand and axial substituents affect the chemical properties of λ 3 -iodanes by analyzing natural bond orbital charges, local vibrational modes, the covalent/electrostatic character, and the three-center four-electron bonding character. In summary, our results show for the first time that there is a smooth transition between halogen bonding → 3c–4e bonding in trihalides → 3c–4e bonding in hypervalent iodine compounds → covalent bonding, opening a manifold of new avenues for the design of hypervalent iodine compounds with specific properties.

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Section: Introductionmentioning

confidence: 99%

A Continuum from Halogen Bonds to Covalent Bonds: Where Do λ3 Iodanes Fit?

et al. 2019

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“…[1][2][3] With the rise of nanotechnology, lowdimensional structures have enormous potential applications in electronics and optoelectronics. [4][5][6][7][8][9][10][11] For example, recently proposed two-dimensional and nanowire arrays materials have peculiar magnetic and optical properties, providing novel possibilities for traditional electronic devices. [12][13][14][15][16] We have put the focus on the potential properties of these new materials.…”

Section: Introductionmentioning

confidence: 99%

Comparison of quantum and collection efficiency of field‐assisted uniform‐doping and exponential‐doping GaN nanowire cathodes

Liu

2020

Int J Energy Res

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Summary The field‐assisted method is proposed to increase electron capture of the GaN nanowire cathode. We deduce the photoemission or electron collection efficiencies of the field‐assisted uniform‐doping and exponential‐doping cathodes using the diffusion‐drift formula. Results show that the external electric field has a significantly better collection efficiency for uniform‐doping nanowire cathodes than that of exponential‐doping. In cathodes without a build‐in field, quantum efficiency and collection efficiency reached a maximum at incident angles of 65° and 45°, and field intensity of 0.1 and 0.7 V/μm, respectively. The external electric field also contributes to the polarization of GaN nanowires. The field‐assisted GaN NWAs (nanowirearray) cathode could improve the photoemission performance and are expected to be realized in the follow‐up experiment.

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“…Among the well-known examples are highly electron-delocalized (eg, species containing planar tetracoordinate or hypercoordinate carbons) and highly strained (eg, hydrocarbon cages and twisted double bonds) structures, many of which have been the subject of numerous computational and experimental studies. [1] Here, we will address our interest in strained hydrocarbon alkenes, particularly alkenes with twisted double bonds. [2] Although double bonds typically favor planar geometries due to sp 2 -hybridization of the carbon atoms, there are ways to achieve "twisted" double bonds.…”

Section: Introductionmentioning

confidence: 99%

The quest for a triplet ground‐state alkene: Highly twisted C═C double bonds

Hommes

Lenoir

et al. 2019

J of Physical Organic Chem

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Density functional theory and extrapolated CCSD(T) computations of several "anti-Bredt" alkenes were carried to explore possible 1,2-diyl "alkene" candidates with a triplet ground state. Ten candidates containing twisted double bonds at the bridgehead positions of bicyclic structures (1-6) or adamantene (7-10) derivatives were studied. Based on a combination of ring strain, rigid scaffolding, and steric crowding, four species were identified to have surprisingly low singlet-triplet energy gaps (lower than 4 kcal/mol). A tert-butyl substituted bicyclic structure (4) was identified to have a near-zero singlettriplet energy gap, but no triplet ground-state alkene was found. Ring strain energy (RSE) calculations, π-orbital axis vector (POAV) analyses, and multiple linear regression models were performed to elucidate the geometric and energetic effects of double bond twisting in 1-10. Based on our computational exploration, it appears unlikely that there is a ground-state triplet olefin.

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Four Decades of the Chemistry of Planar Hypercoordinate Compounds

Cited by 229 publications

References 299 publications

A Continuum from Halogen Bonds to Covalent Bonds: Where Do λ3 Iodanes Fit?

A Continuum from Halogen Bonds to Covalent Bonds: Where Do λ3 Iodanes Fit?

Comparison of quantum and collection efficiency of field‐assisted uniform‐doping and exponential‐doping GaN nanowire cathodes

The quest for a triplet ground‐state alkene: Highly twisted C═C double bonds

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