Exploration of the pentacyano-cyclo-pentadienide ion, C5(CN)5−, as a weakly coordinating anion and potential superacid conjugate base. Silylation and protonation

Richardson, Christopher J. K.; Reed, Christopher A.

doi:10.1039/b316122f

Cited by 55 publications

(45 citation statements)

References 14 publications

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“…However, the recent pioneering success of Richardson and Reed [68] in protonating the C 5 (CN) 5 -anion is encouraging, because this is one of the most stable anions we examined so far. [13][14][15]18] It is noteworthy that the proton was found to be attached exclusively to the nitrogen atom [68] in accordance with our theoretical calculation, [15] which has shown that the acid had a planar heavy atoms structure containing a ketene imine C=C=NH moiety. In other words, [C 5 (CN) 4 ]C=NH is an NH and not a CH acid, at least in its most stable form.…”

Section: Discussionmentioning

confidence: 85%

Strong Acidity of Some Polycyclic Aromatic Compounds Annulated to a Cyclopentadiene Moiety and Their Cyano Derivatives – A Density Functional B3LYP Study

Vianello

Maksić

2005

Eur J Org Chem

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The acidity of the parent 1H‐benz[f]indene (1a), 1H‐benz[e]indene (2a), 1H‐benz[fg]acenaphthylene (3a) and 1H‐cyclopenta[l]phenanthrene (4a) and of their polycyano derivatives is examined in the gas phase and in DMSO by the DFT‐B3LYP methods. It is shown that the parent hydrocarbons exhibit modest acidities, whereas a dramatic increase in acidity is observed upon multiple cyanation leading to hyperstrong neutral organic superacids. It is found that polycyano derivatives undergo prototropic tautomerism with a consequence that the most stable tautomer contains a ketene imine C=C=NH functionality. The origin of their highly pronounced acidity is identified as a very strong anionic resonance effect efficiently assisted by a large number of CN groups in a concerted manner. It is stressed that the polycyanated anions are very stable and have a highly dispersed negative charge, which should lead to a low nucleophilicity and weak coordinating properties, thus making them potentially very useful in academic research and technological applications. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

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Section: Discussionmentioning

confidence: 85%

Strong Acidity of Some Polycyclic Aromatic Compounds Annulated to a Cyclopentadiene Moiety and Their Cyano Derivatives – A Density Functional B3LYP Study

Vianello

Maksić

2005

Eur J Org Chem

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“…It is interesting to note the structural change in the dimer units from a 1,2-(CN) 2 . The crystallographically independent octahedral (tmeda) 2 NaA C H T U N G T R E N N U N G (N C-) 2 configurations at Na1 and Na2 are of opposite chirality.…”

Section: Resultsmentioning

confidence: 99%

A Simple Approach to Coordination Compounds of the Pentacyanocyclopentadienide Anion

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McPartlin

Rawson

et al. 2010

Chemistry A European J

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Deprotonation of [Et(3)NH][C(5)(CN)(5)] with metal bases provides a very simple approach to coordination compounds containing the pentacyanocyclopentadienide anion [C(5)(CN)(5)](-) (1). The three-dimensional polymer [Na(thf)(1.5)(1)](∞) and the molecular dimer [{(tmeda)(2)Na(1)}(2)] are obtained by reaction of this precursor with NaH in the presence of thf or tmeda (Me(2)NCH(2)CH(2)NMe(2)). Their single-crystal X-ray structures both reveal σ-bonded C≡N-Na arrangements and π stacking between [C(5)(CN)(5)](-) ions. DFT calculations on the [C(5)(CN)(5)](-) ion have been used to investigate the structures and bonding in [Na(thf)(1.5)(1)](∞) and [{(tmeda)(2)Na(1)}(2)]. The absence of π bonding of the metal ions in both complexes is due to dispersion of the negative charge from the C(5) ring unit to the C[triple chemical bond]N groups in the [C(5)(CN)(5)](-) ion, making the coordination chemistry of this anion distinctly different from that of cyclopentadienide C(5)H(5)(-).

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“…[1] It has been found that the conjugate acid of the anion C 5 (CN) 5 À forms a stable polymeric structure in the solid phase whereby every proton is simultaneously bound to two anions [9] and the acid is weaker than could be expected from computations.…”

Section: Superacidsmentioning

confidence: 99%

Boratabenzene Anions C₅B(CN)₆⁻ and C₅B(CF₃)₆⁻ and the Superacidic Properties of their Conjugate Acids

Kütt

Koppel

et al. 2009

ChemPhysChem

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Designing superacids: A computational study of protonated boratabenzenes and the gas-phase acidity of their conjugate acids is presented. Conjugate acids of boratabenzenes substituted with CN or CF(3) groups (see figure) are highly acidic species; the protonated hexacyanoboratabenzene and hexakis(trifluoromethyl)boratabenzene have computational gas-phase acidities of 250.5 and 276.8 kcal mol(-1), respectively.

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Exploration of the pentacyano-cyclo-pentadienide ion, C₅(CN)₅⁻, as a weakly coordinating anion and potential superacid conjugate base. Silylation and protonation

Cited by 55 publications

References 14 publications

Strong Acidity of Some Polycyclic Aromatic Compounds Annulated to a Cyclopentadiene Moiety and Their Cyano Derivatives – A Density Functional B3LYP Study

Strong Acidity of Some Polycyclic Aromatic Compounds Annulated to a Cyclopentadiene Moiety and Their Cyano Derivatives – A Density Functional B3LYP Study

A Simple Approach to Coordination Compounds of the Pentacyanocyclopentadienide Anion

Boratabenzene Anions C₅B(CN)₆⁻ and C₅B(CF₃)₆⁻ and the Superacidic Properties of their Conjugate Acids

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Exploration of the pentacyano-cyclo-pentadienide ion, C5(CN)5−, as a weakly coordinating anion and potential superacid conjugate base. Silylation and protonation

Cited by 55 publications

References 14 publications

Strong Acidity of Some Polycyclic Aromatic Compounds Annulated to a Cyclopentadiene Moiety and Their Cyano Derivatives – A Density Functional B3LYP Study

Strong Acidity of Some Polycyclic Aromatic Compounds Annulated to a Cyclopentadiene Moiety and Their Cyano Derivatives – A Density Functional B3LYP Study

A Simple Approach to Coordination Compounds of the Pentacyanocyclopentadienide Anion

Boratabenzene Anions C5B(CN)6− and C5B(CF3)6− and the Superacidic Properties of their Conjugate Acids

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Exploration of the pentacyano-cyclo-pentadienide ion, C₅(CN)₅⁻, as a weakly coordinating anion and potential superacid conjugate base. Silylation and protonation

Boratabenzene Anions C₅B(CN)₆⁻ and C₅B(CF₃)₆⁻ and the Superacidic Properties of their Conjugate Acids