Gas-Phase Thermochemistry of Polyhalide Anions

Nizzi, Katrina Emilia; Pommerening, Cynthia Ann; Sunderlin, Lee S.

doi:10.1021/jp9824508

Cited by 47 publications

(64 citation statements)

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“…The calculated value of −78.2 kcal/mol for Cl 3 − is in excellent agreement with the experimental one of −77.9 ± 1.2 kcal/mol, 38 as is the value of −73.2 kcal/mol for Br 3 − compared to the experimental one of −73.9 ± 1.7 kcal/mol. 38 The experimental value for I 3 − is −60.2 ± 1.4 kcal/mol, 39 and the computational results are in good agreement with the experimental value, being slightly more negative. There is a slightly larger difference between the computational and experimental results for Br 5 − with an experimental value of −75.5 ± 2.4 kcal/mol.…”

Section: ■ Computational Proceduressupporting

confidence: 84%

“…9,17,33−35 The I 3 + was synthesized and characterized by both spectroscopic and crystallographic techniques. 13,17,19,36,37 The Cl 3 − , Br 3 − , and I 3 − anions have been observed in the gas phase, 38,39 in solution, 40−42 and in the solid state 43−45 and characterized by spectroscopic techniques. 46−58 These trihalide anions (X 3 − ) are linear and symmetric in solution, while in the solid phase both symmetric and asymmetric structures are found with the small deviations from linearity being caused by crystal packing forces.…”

Section: ■ Introductionmentioning

confidence: 99%

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Structures, Vibrational Frequencies, and Stabilities of Halogen Cluster Anions and Cations, X_n^+/–, n = 3, 4, and 5

et al. 2014

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The structures, vibrational frequencies, and thermodynamic stabilities of the homonuclear polyhalogen ions, X3(+), X3(-), X4(+), X4(-), X5(+), and X5(-) (X = Cl, Br, I), have been calculated at the CCSD(T) level. The energetics were calculated using the Feller-Peterson-Dixon approach for the prediction of reliable enthalpies of formation. The calculations allow the following predictions where stabilities are defined in terms of thermodynamic quantities. (1) The X3(+) cations are stable toward loss of X2; (2) the X3(-) anions are marginally stable toward loss of X2 with Cl3(-) being the least stable; (3) the X4(+) cations and X4(-) anions are only weakly bound dimers of X2(+1/2) and X2(-1/2) units, respectively, but the cations are marginally stable toward decomposition to X3(+) and X, with I4(+) having the lowest dissociation energy, whereas the X4(-) anions decompose spontaneously to X3(-) and X; (4) the X5(+) cations are only marginally stable at low temperatures toward loss of X2, with Cl5(+) being the least stable; and (5) the X5(-) anions are also only stable at low temperatures toward loss of X2, with Cl5(-) being the least stable.

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Section: ■ Computational Proceduressupporting

confidence: 84%

Section: ■ Introductionmentioning

confidence: 99%

Structures, Vibrational Frequencies, and Stabilities of Halogen Cluster Anions and Cations, X_n^+/–, n = 3, 4, and 5

et al. 2014

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“…17 Our results, together with the energetics shown below, indicate that such polyhalogen anions could stably exist inside the carbon nanotube. 18 The binding strength for the bromine adsorbates inside nanotubes with various diameters is investigated mainly with LDA, as shown in Fig. 2.…”

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confidence: 99%

Formation of polybromine anions and concurrent heavy hole doping in carbon nanotubes

Sung

Park

et al. 2007

Applied Physics Letters

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Using density-functional theory calculations, we investigate the atomic and electronic structure of the bromine species encapsulated in carbon nanotubes. We find that the odd-membered molecular structures (Br3 and Br5) are energetically favored than the common Br2 molecule. The transformation from bromine molecules (Br2) into Br3 or Br5 is found to be almost barrierless. A strong electron transfer from the nanotube to the adsorbates, which has been doubtful in previous studies, is accompanied by the formation of such odd-membered polybromine anions. We suggest that the tip-opened carbon nanotube samples can be heavily hole-doped after exposure to Br2 gas.

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“…Even though the EAs of halogen dimers are lower than that of their corresponding halogen atoms, it is known that the subsequent, higher oligomers of halogens, X n (n 4 2) do have large EA values. 26,27 Since, the EA values of all the (BO 2 ) n oligomers studied here are consistently larger than that of the Cl atom (3.61 eV), these clusters are classified as superhalogens. But most importantly, their EA values are either larger than or comparable to the EA of the BO 2 building unit.…”

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confidence: 79%

Superhalogens beget superhalogens: a case study of (BO₂)_n oligomers

Kandalam

Kiran

Jena

et al. 2015

Phys. Chem. Chem. Phys.

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Superhalogens belong to a class of molecules that not only mimic the chemistry of halogen atoms but also possess electron affinities that are much larger than that of chlorine, the element with the highest electron affinity in the periodic table. Using BO 2 as an example and the synergy between density functional theorybased calculations and photoelectron spectroscopy experiments we demonstrate another unusual property of superhalogens. Unlike halogens, whose ability to accept an electron falls upon dimerization, B 2 O 4 , the dimer of BO 2 , has an electron affinity larger than that of the BO 2 building block. This ability of (BO 2 ) 2 and subsequent, higher oligomers (BO 2 ) n (n = 3 and 4), to retain their superhalogen characteristics can be traced to the enhanced bonding interactions between oxygen and boron atoms and due to the delocalization of the charge of the extra-electron over the terminal oxygen atoms. These results open the door to the design and synthesis of a new class of metal-free highly negative ions with potential for novel applications.Negative ions play an important role in chemistry not only because they are the building blocks of salts, but also because they are useful in purifying air, killing molds, and serving as anti-depressants. Halogens atoms readily form negative ions and have among the highest electron affinities of any element in the periodic table. However, as shown in Table 1, when halogen atoms combine to form molecules, their electron affinities are reduced, 1 i.e. halogens do not beget halogens. This decreasing trend is a consequence of the extra-electron occupying the antibonding orbital of X 2 (X = F, Cl, Br, and I) molecule. In this communication, we show that in contrast to halogens, dimerization of BO 2 , a well-known superhalogen, does not result in lowering of the EA. In addition, the higher oligomers, (BO 2 ) n (n = 3 and 4) also retain their superhalogen characteristics.More than half a century ago it was shown that PtF 6 could oxidize a Xe atom. 2 The electron affinity of this molecule was later estimated to be 6.76 eV, 3 much larger than the electron affinity of any halogen atom. Gutsev and Boldyrev 4 later termed such molecules as superhalogens and generalized the concept to include molecules with composition MX (m+1)/n , where m is the maximal valence of the metal atom M and n is the normal valence of the electronegative atom, X (n = 1 for halogen atoms). Subsequently, several experimental studies have confirmed the existence of superhalogens consisting of simple metal atoms, such as alkalis, Mg, and Al at the core and halogen atoms on the periphery. 5-7 Considerable research conducted in recent years has shown that superhalogens not only mimic the chemistry of halogens but also can be used to promote unusual reactions, 8 as a building block of energetic materials, 9 as dopants to increase the electrical conductivity of polymers, 10 for accessing high oxidation states of metal atoms, 11 as electrolytes in rechargeable batteries, 12 and in the production of organi...

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Gas-Phase Thermochemistry of Polyhalide Anions

Cited by 47 publications

References 37 publications

Structures, Vibrational Frequencies, and Stabilities of Halogen Cluster Anions and Cations, X_n^+/–, n = 3, 4, and 5

Structures, Vibrational Frequencies, and Stabilities of Halogen Cluster Anions and Cations, X_n^+/–, n = 3, 4, and 5

Formation of polybromine anions and concurrent heavy hole doping in carbon nanotubes

Superhalogens beget superhalogens: a case study of (BO₂)_n oligomers

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Gas-Phase Thermochemistry of Polyhalide Anions

Cited by 47 publications

References 37 publications

Structures, Vibrational Frequencies, and Stabilities of Halogen Cluster Anions and Cations, Xn+/–, n = 3, 4, and 5

Structures, Vibrational Frequencies, and Stabilities of Halogen Cluster Anions and Cations, Xn+/–, n = 3, 4, and 5

Formation of polybromine anions and concurrent heavy hole doping in carbon nanotubes

Superhalogens beget superhalogens: a case study of (BO2)n oligomers

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Structures, Vibrational Frequencies, and Stabilities of Halogen Cluster Anions and Cations, X_n^+/–, n = 3, 4, and 5

Structures, Vibrational Frequencies, and Stabilities of Halogen Cluster Anions and Cations, X_n^+/–, n = 3, 4, and 5

Superhalogens beget superhalogens: a case study of (BO₂)_n oligomers