Aromatic Superhalogens

Child, Brandon Z.; Giri, Santanab; Gronert, Scott; Jena, P.

doi:10.1002/chem.201305057

Cited by 50 publications

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“…For benzene, n ¼ 1. The electron affinity of hexacyanobenzene [C 6 (CN) 6 ] is 3.53 eV, 25,27 substantially higher than that of C 6 H 6 . benzene is unstable as a mono-anion.…”

Section: àmentioning

confidence: 99%

Unusual stability of multiply charged organo-metallic complexes

et al. 2015

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Stabilization of multiply charged ions in the gas phase has been one of the most fundamental challenges in chemistry since it is hindered either because of fragmentation or auto-electron detachment. Closo-borane B 12 H 12 2À is among the best known multiply charged di-anion in chemistry where the second electron is bound by 0.9 eV. We show that transition metal based organo-metallic di-anions such as Cr[BC 5 (CN) 6 ] 2 can be even more stable than B 12 H 12 2À where the second electron is bound by 2.58 eV. This is in contrast to C 6 H 6 which is unstable even as a mono-anion. The unusual stability of the organo-metallic complex is brought about by having the added electrons simultaneously satisfy three separate electroncounting rules, namely the octet rule, the aromaticity rule, and the 18-electron rule. Mono-anionic Mn[BC 5 (CN) 6 ] 2 which is isoelectronic with di-anionic Cr[BC 5 (CN) 6 ] 2 is also found to be very stable. The design of unusually stable singly and multiply charged organo-metallic negative ion complexes in the gas phase opens the door to the synthesis of new salts with potential applications as organic cathodes and electrolytes in Li ion-batteries and beyond. Equally important, electron counting rules can be used effectively to guide the synthesis of electronegative species beyond super-and hyperhalogens, and hence opening the door for new oxidizing agents.Over the past 30 years the study of multiply charged molecular ions has been a topic of great interest 1 not only because they enable a fundamental understanding of interstellar chemistry but also for their potential as building blocks of salts and Zintl phase compounds, fusion devices, high intensity ion sources, and use in analytic mass spectrometry of large biomolecules. Multiply charged species are commonly seen in solutions or in a condensed phase where they are stabilized either by counterions or interaction with the solvent molecules. Their stability in the gas phase, however, is governed by a delicate balance between the repulsive Coulomb forces and attractive interaction generated by chemical bonding and charge/induceddipole interactions. Small multiply charged molecular negative ions in the gas phase are seldom stable due to spontaneous emission of electron (the so-called auto-detachment) or fragmentation into mono-anions. In the early 1990's observation of long-lived cluster di-anions such as C 60 2À could be explained 2 by the existence of substantial Coulomb barriers that hinder the emission of one of the excess electrons. More recently, electronic stability of di-anionic metal hexauoride complexes such as ZrF 6 2À , rst predicted by theory, 3-5 has been conrmed by photoelectron spectroscopy experiments, 6 but their thermodynamic stability is not addressed. How small a cluster can bind two extra electrons without auto-detaching or fragmenting remains an unanswered question. A classic example of a thermodynamically stable di-anion is B 12 H 12 2À. This cluster belongs to the class of closo-boranes, B n H n 2À , whose stability g...

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“…For benzene, n ¼ 1. The electron affinity of hexacyanobenzene [C 6 (CN) 6 ] is 3.53 eV, 25,27 substantially higher than that of C 6 H 6 . benzene is unstable as a mono-anion.…”

Section: àmentioning

confidence: 99%

Unusual stability of multiply charged organo-metallic complexes

et al. 2015

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“…[13] Owing to these potential applications,c onsiderable work in recent years has greatly expanded the pool of superhalogens.T hey now include moieties where the core metal atom can be replaced by ac luster of atoms, [14] and/orh alogen atoms can be replaced by oxygen [15] or superhalogenm olecules such as CN and BO 2 .Super-and hyperhalogens can even be formed without the benefito f as ingle metal or halogena tom. [19] Indeed, the EAs of C 6 F 6 and C 6 (CN) 6 are found to be 0.75 and 3.53 eV, [20] making the latter even behavel ike Cl. Ac lassic example is benzene;i ts EA is À1.15 eV.…”

Section: Introductionmentioning

confidence: 99%

“…Recently,s chemes making use of electron-counting rules have been developed [20,21] to systematically increase the EAs of organic molecules even further, making them behave like superhalogens. For example, the EA of C 5 H 5 can be increased to 5.59 eV by replacing Hw ith CN.…”

Section: Introductionmentioning

confidence: 99%

From Halogen to Superhalogen Behavior of Organic Molecules Created by Functionalizing Benzene

et al. 2015

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Benzene, the classic organic molecule obeying Hückel's rule of aromaticity, has negative electron affinity (EA), namely -1.15 eV. By using density functional theory with hybrid functional for exchange and correlation potential, we show that a series of organic molecules created by changing either the benzene core or the ligands, or both, result in species with EAs that range from 2.15 to 5.37 eV. This shows that ligand substitution is more effective than aromaticity in increasing the EA of organic molecules. The ability to create highly electronegative organic molecules by functionalizing benzene may provide new opportunities for synthesizing organic oxidizing agents with potential new applications.

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“…21,35-37 On the other hand, much of the experimental work was produced in the Bowen, 38,39 Brauman, 40,41 Compton, 42, 43 Desfrançois,44,45 Johnson, 46,47 and Lineberger 48,49 groups. [57][58][59][60][61][62][63][64][65][66][67][68][69] Suffice it to say that the superhalogens MX k+1 and their anionic daughters (MX k+1 ) À are usually composed of a central atom M (which is preferably metallic although semi-metals (e.g. [50][51][52][53][54][55] Since the large electronic stability of superhalogen anions plays an important role in our discussion provided in the following sections, one needs to recall that such anions (whose existence and properties were first described by Gutsev and Boldyrev in 1981) 56 are typically very strongly bound systems which is manifested by their vertical electron binding energies spanning the 3.6-13.9 eV range.…”

Section: Introductionmentioning

confidence: 99%

The HAlF₄ superacid fragmentation induced by an excess electron attachment

Czapla

Skurski

2015

Phys. Chem. Chem. Phys.

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The excess electron attachment to the HAlF4 superacid molecule was studied by employing ab initio CCSD(T) and MP2 methods and a purposely suited aug-cc-pVTZ+4s4p3d basis set. The results indicate that the HAlF4 molecule, due to its polarity, may attract a distant excess electron and form a dipole-bound anionic state whose vertical electron binding energy is 1106 cm(-1). The initially formed (HAlF4)(-) anion of a dipole-bound nature undergoes an immediate structural reorganization driven by the (AlF4)(-) strongly-bound superhalogen anion formation. The potential energy surface analysis leads to the conclusion that the (HAlF4)(-) → (AlF4)(-) + H transformation should proceed spontaneously and involve the simultaneous structure relaxation of the AlF4 moiety (in the direction approaching a tetrahedral geometry) and the excess electron density migration from the area outside the molecular framework to the valence AlF4 region. The fragmentation of the HAlF4 superacid molecule is predicted to be the final effect of the excess electron attachment process. In addition, the important antenna role of the initially formed (HAlF4)(-) dipole-bound anionic state is discussed.

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Aromatic Superhalogens

Abstract: It has been noticed that Figure 7 in this Full Paper was reproduced incorrectly. The correct Figure is depicted below. Figure 7. Geometries of next higher-energy isomers of neutral C 13-m H 9-m N m (m = 0-3, 9) molecules. Bond lengths are given in .

Cited by 50 publications

References 57 publications

Unusual stability of multiply charged organo-metallic complexes

Unusual stability of multiply charged organo-metallic complexes

From Halogen to Superhalogen Behavior of Organic Molecules Created by Functionalizing Benzene

The HAlF₄ superacid fragmentation induced by an excess electron attachment

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Aromatic Superhalogens

Abstract: It has been noticed that Figure 7 in this Full Paper was reproduced incorrectly. The correct Figure is depicted below. Figure 7. Geometries of next higher-energy isomers of neutral C 13-m H 9-m N m (m = 0-3, 9) molecules. Bond lengths are given in .

Cited by 50 publications

References 57 publications

Unusual stability of multiply charged organo-metallic complexes

Unusual stability of multiply charged organo-metallic complexes

From Halogen to Superhalogen Behavior of Organic Molecules Created by Functionalizing Benzene

The HAlF4 superacid fragmentation induced by an excess electron attachment

Contact Info

Product

Resources

About

Abstract: It has been noticed that Figure 7 in this Full Paper was reproduced incorrectly. The correct Figure is depicted below. Figure 7. Geometries of next higher-energy isomers of neutral C 13-m H 9-m N m (m = 0-3, 9) molecules. Bond lengths are given in .

The HAlF₄ superacid fragmentation induced by an excess electron attachment