A path to design stronger superacids by using superhalogens

Srivastava, Ambrish Kumar; Kumar, Abhishek; Misra, Neeraj

doi:10.1016/j.jfluchem.2017.03.001

Cited by 32 publications

(26 citation statements)

References 21 publications

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“…The compound 11i is stronger than or have comparable acidity with many organic and inorganic superacids reported so far. For example, it is stronger than (AlF 3 ) 2 HClO 4 (∆ G acid = 257.1 kcal mol −1 ), (SbF 5 ) 2 HClO 4 (∆ G acid = 252.0 kcal mol −1 ), B 12 Cl 1 H 11 H 2 (∆ G acid = 261.1 kcal mol −1 ), B 12 F 1 H 11 H 2 (∆ G acid = 265.2 kcal mol −1 ), CB 11 F 1 H 11 H (∆ G acid = 265.2 kcal mol −1 ), C 5 (CN) 5 H (∆ H acid = 263.5 kcal mol −1 ), and HB(BF 4 ) 4 (∆ G acid = 257.7 kcal mol −1 ) …”

Section: Resultsmentioning

confidence: 99%

“…For example, it is stronger than (AlF 3 ) 2 HClO 4 (ΔG acid = 257.1 kcal mol −1 ), [29] (SbF 5 ) 2 HClO 4 (ΔG acid = 252.0 kcal mol −1 ), [29] [17] C 5 (CN) 5 H (ΔH acid = 263.5 kcal mol −1 ), [21] and HB(BF 4 ) 4 (ΔG acid = 257.7 kcal mol −1 ). [63] T Note: The numbers in the parenthesis are ZPVE-corrected energies.…”

Section: Compounds With Fused Cyclopentadiene and Pyrrole Ringsmentioning

confidence: 99%

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Design of new organic superacids with fused and isolated pyrrole and cyclopentadiene rings and assessment of effect of –BX₂(X = H, F, Cl, CN) substituents on the acidity enhancement: A DFT analysis

Parsazadeh

Valadbeigi

Rouhani

2019

Int J of Quantum Chemistry

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New classes of organic Brønsted acids were designed with pyrrole and cyclopentadiene scaffolds, and their acidity was assessed theoretically by the B3LYP/6‐311++G(d,p) method. The hydrogen atom of NH group in pyrrole was substituted by an –BX2 (X = H, F, Cl, CN, CF3). The boron atom stabilizes the conjugated bases by interaction with the center of negative charge after deprotonation. The acidity of the compounds was promoted by substitution of the hydrogen atoms of the rings with CN moiety as a strong electron withdrawing group. Also, after deprotonation, delocalization of the negative charge in both pyrrole and cyclopentadiene rings causes stability of the conjugated bases and consequently enhances the acidity. The charge delocalization in the neutral acids and their conjugated bases was compared using nucleus‐independent chemical shift index. Enthalpies and Gibbs free energies of deprotonation in gas phase, ∆Hacid and ∆Gacid, were used as a measure of acidity. Both compounds with isolated and fused pyrrole and cyclopentadiene rings were investigated and it was found that the formers are more acidic. Using these strategies, several acids and superacids with wide range of acidity with ∆Gacid values of 244 to 328 kcal mol−1 were obtained.

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Section: Resultsmentioning

confidence: 99%

Section: Compounds With Fused Cyclopentadiene and Pyrrole Ringsmentioning

confidence: 99%

Design of new organic superacids with fused and isolated pyrrole and cyclopentadiene rings and assessment of effect of –BX₂(X = H, F, Cl, CN) substituents on the acidity enhancement: A DFT analysis

Parsazadeh

Valadbeigi

Rouhani

2019

Int J of Quantum Chemistry

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“…It should also be noted that such a search for new systems possessing significant acid strength might be carried out by combining selected superhalogen anions (originally proposed by Gutsev and Boldyrev [38] and identified experimentally almost two decades later [39] ) with the additional proton. [25] even though several very strong acids have been recently proposed by following this route [25][26][27][28][40][41][42][43] most of them have not been experimentally obtained thus far. Therefore, it seems that the strongest superacids presently known (i. e., experimentally confirmed) are carborane acids whose enormous acid strength is likely related to the large stability of the icosahedral CB 11 'carborane core'.…”

Section: Introductionmentioning

confidence: 99%

Icosahedral Carborane Superacids and their Conjugate Bases Comprising H, F, Cl, and CN Substituents: A Theoretical Investigation of Monomeric and Dimeric Cages

2020

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Theoretical investigation of the H(CHB11X11) (X=H, F, Cl, CN), H(CHB11XnY11‐n) (X,Y=F, Cl; n=1,5), and dimeric (H(CHB11X11))2 (X=F, Cl) carborane superacids performed at the B3LYP/6‐311++G(d,p) theory level revealed the similarity of their equilibrium structures and the possibility of nearly barrierless hydrogen atom migration among the substituents attached to one side of the icosahedral CB11 cage. The vertical electron detachment energies predicted at the OVGF/6‐311++G(3df,2pd) theory level for the conjugate bases (CHB11X11)− were found to span the 5.82–9.00 ev range. The acid strengths (manifested by the Gibbs free deprotonation energies spanning the 213–266 kcal/mol range) predicted for the icosahedral H(CHB11X11) carborane systems confirm their superacidic properties which might be increased even further by the attachment of the second carborane H(CHB11X11) unit that leads to a dimeric structure mimicking a part of an experimentally observed H‐bridged polymeric chain. The Gibbs free deprotonation energy of the dimeric (H(CHB11Cl11))2 acid was predicted to be smaller by 17 kcal/mol than that of the corresponding monomeric H(CHB11Cl11) acid.

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“…[4][5][6][7] Not only that, superhalogen is used as a building block for many superacids. [27][28][29][30][31][32][33] By looking at the versatile properties and applications of superhalogen we have made an attempt to design super Lewis acids by using superhalogen ligands. For the designing of super Lewis acids, in this work, we have used boron as the central atom and organic heterocyclic compounds as ligands.…”

Section: Introductionmentioning

confidence: 99%

Superhalogens as Building Blocks of Super Lewis Acids

et al. 2019

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Lewis acids play an important role in synthetic chemistry. Using first‐principle calculations on some newly designed molecules containing boron and organic heterocyclic superhalogen ligands, we show that the acid strength depends on the charge of the central atom as well as on the ligands attached to it. In particular, the strength of the Lewis acid increases with increasing electron withdrawing power of the ligand. With this insight, we highlight the importance of superhalogen‐based ligands in the design of strong Lewis acids. Calculated fluoride ion affinity (FIA) values of B[C2BNO(CN)3]3 and B[C2BNS(CN)3]3 show that these are super Lewis acids.

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A path to design stronger superacids by using superhalogens

Cited by 32 publications

References 21 publications

Design of new organic superacids with fused and isolated pyrrole and cyclopentadiene rings and assessment of effect of –BX₂(X = H, F, Cl, CN) substituents on the acidity enhancement: A DFT analysis

Design of new organic superacids with fused and isolated pyrrole and cyclopentadiene rings and assessment of effect of –BX₂(X = H, F, Cl, CN) substituents on the acidity enhancement: A DFT analysis

Icosahedral Carborane Superacids and their Conjugate Bases Comprising H, F, Cl, and CN Substituents: A Theoretical Investigation of Monomeric and Dimeric Cages

Superhalogens as Building Blocks of Super Lewis Acids

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A path to design stronger superacids by using superhalogens

Cited by 32 publications

References 21 publications

Design of new organic superacids with fused and isolated pyrrole and cyclopentadiene rings and assessment of effect of –BX2(X = H, F, Cl, CN) substituents on the acidity enhancement: A DFT analysis

Design of new organic superacids with fused and isolated pyrrole and cyclopentadiene rings and assessment of effect of –BX2(X = H, F, Cl, CN) substituents on the acidity enhancement: A DFT analysis

Icosahedral Carborane Superacids and their Conjugate Bases Comprising H, F, Cl, and CN Substituents: A Theoretical Investigation of Monomeric and Dimeric Cages

Superhalogens as Building Blocks of Super Lewis Acids

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Design of new organic superacids with fused and isolated pyrrole and cyclopentadiene rings and assessment of effect of –BX₂(X = H, F, Cl, CN) substituents on the acidity enhancement: A DFT analysis

Design of new organic superacids with fused and isolated pyrrole and cyclopentadiene rings and assessment of effect of –BX₂(X = H, F, Cl, CN) substituents on the acidity enhancement: A DFT analysis