The Bonding of Trihalide and Bifluoride Ions by the Molecular Orbital Method

Pimentel, George C.

doi:10.1063/1.1748245

Cited by 644 publications

(329 citation statements)

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“…We showed earlier the various diborane phases considered. Of these, we took the β form to higher pressure and compared its enthalpy to those of extended arrays of molecular trimer, tetramer, hexamer, and infinite chain of BH 3 . The optimized structures we found (at 40 GPa) are shown in Figure 5, and their enthalpies as a function of pressure in Figure 6.…”

Section: Journal Of the American Chemical Societymentioning

confidence: 99%

“…XXXX, XXX, XXX−XXX trimer, has not been unambiguously characterized in experiments. Fridmann and Fehlner 44 observed the formation of a triborane product, suggested to be B 3 H 9 , in the reaction of BH 3 and B 2 H 6 . Theoretical calculations 45 suggested that the step II is associated with activation and reaction enthalpies (at 400 K) of approximately 14 and −5 kcal/mol, respectively.…”

Section: Journal Of the American Chemical Societymentioning

confidence: 99%

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BH₃ under Pressure: Leaving the Molecular Diborane Motif

Yao

Hoffmann

2011

J. Am. Chem. Soc.

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Molecular and crystalline structures of (BH 3 ) n have been theoretically studied in the pressure regime from 1 atm to 100 GPa. At lower pressures, crystals of the familiar molecular dimer are the structure of choice. At 1 atm, in addition to the well-characterized β diborane structure, we suggest a new polymorph of B 2 H 6 , fitting the diffraction lines observed in the very first X-ray diffraction investigation of solid diborane, that of Mark and Pohland in 1925. We also find a number of metastable structures for oligomers of BH 3 , including cyclic trimers, tetramers, and hexamers. While the higher oligomers as well as one-dimensional infinite chains (bent at the bridging hydrogens) are less stable than the dimer at ambient pressure, they are stabilized, for reasons of molecular compactness, by application of external pressure. Using periodic DFT calculations, we predict that near 4 GPa a molecular crystal constructed from discrete trimers replaces the β diborane structure as the most stable phase and remains as such until 36 GPa. At higher pressures, a crystal of polymeric, one-dimensional chains is preferred, until at least 100 GPa.

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Section: Journal Of the American Chemical Societymentioning

confidence: 99%

Section: Journal Of the American Chemical Societymentioning

confidence: 99%

BH₃ under Pressure: Leaving the Molecular Diborane Motif

Yao

Hoffmann

2011

J. Am. Chem. Soc.

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“…Oxygen with a ground-state atomic configuration of 1s 2 2s 2 2p x 2 2p y 1 2p z 1 has a nominal valence of two and forms stable compounds such as H 2 O and F 2 O (as well as the radicals OH and OF, which have one unsatisfied valence). However, main group elements beyond the first row regularly form stable molecules that exceed their nominal valence, e.g., sulfur, which is in the same group as oxygen, forms SF 4 and SF 6 in which sulfur has a valence of 4 and 6, respectively. Musher 1 and Schleyer 2 coined the terms "hypervalent" and "hypercoordinated," respectively, to denote molecules where the nominal valence of the atoms is exceeded.…”

Section: Introductionmentioning

confidence: 99%

“…Musher 1 and Schleyer 2 coined the terms "hypervalent" and "hypercoordinated," respectively, to denote molecules where the nominal valence of the atoms is exceeded. Several models have been advanced to rationalize the existence of hypervalent species, the most widely accepted today being the RundlePimentel 3-center, 4-electron (3c-4e) model, which uses basic molecular orbital arguments to rationalize the existence of hypervalent species 3,4 although this rationalization is not without its inconsistencies. 5 Previous studies of the halides of the second row, late p-block elements, by our group have shown that hypervalent or hypercoordinated molecules possess a previously unrecognized type of bond, a recoupled pair bond.…”

Section: Introductionmentioning

confidence: 99%

Fundamental aspects of recoupled pair bonds. I. Recoupled pair bonds in carbon and sulfur monofluoride

Dunning

Takeshita

2015

The Journal of Chemical Physics

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The number of singly occupied orbitals in the ground-state atomic configuration of an element defines its nominal valence. For carbon and sulfur, with two singly occupied orbitals in their 3P ground states, the nominal valence is two. However, in both cases, it is possible to form more bonds than indicated by the nominal valence—up to four bonds for carbon and six bonds for sulfur. In carbon, the electrons in the 2s lone pair can participate in bonding, and in sulfur the electrons in both the 3p and 3s lone pairs can participate. Carbon 2s and sulfur 3p recoupled pair bonds are the basis for the tetravalence of carbon and sulfur, and 3s recoupled pair bonds enable sulfur to be hexavalent. In this paper, we report generalized valence bond as well as more accurate calculations on the a4Σ− states of CF and SF, which are archetypal examples of molecules that possess recoupled pair bonds. These calculations provide insights into the fundamental nature of recoupled pair bonds and illustrate the key differences between recoupled pair bonds formed with the 2s lone pair of carbon, as a representative of the early p-block elements, and recoupled pair bonds formed with the 3p lone pair of sulfur, as a representative of the late p-block elements.

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“…The bonding•in the hydrogen dichloride species can be treated as a three center bond formed from combination of the hydrogen ls orbital and chlorine 3P orbitals [7].…”

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confidence: 99%