Benzonitrile Anion Research Articles

The quest to uncover the nature of benzonitrile anion

Anionic states of benzonitrile are investigated by high-level electronic structure methods. The calculations using equation-of-motion coupled-cluster theory for electron-attached states confirm earlier conclusions drawn from the photodetachment experiments wherein the ground state of the anion is the valence 2B1 state, while the dipole bound state lies adiabatically ∼0.1 eV above. Inclusion of triple excitations and zero-point vibrational energies is important for recovering relative state correct ordering. The computed Franck-Condon factors and photodetachment cross-sections further confirm that the observed photodetachment spectrum originates from the valence anion. The valence anion is electronically bound at its equilibrium geometry, but it is metastable at the equilibrium geometry of the neutral. The dipole-bound state, which is the only bound anionic state at the neutral equilibrium geometry, may serve as a gateway state for capturing the electron. Thus, the emerging mechanistic picture entails electron capture via a dipole bound state, followed by non-adiabatic relaxation forming valence anions.

Configuration and energy landscape of the benzonitrile anion

Quantum chemical calculations are employed to study the configurational isomers of the anion formed by benzene substituted with a cyano group. It is found that an excess electron can form dipole-bound (DB) states with benzonitrile and phenyl-isocyanide isomers. It can also attach to the cyano group, if this group is separated from the benzene ring by some distance, forming a covalent CN− anion. There are four positions at peripherals of the benzene ring where this anion can localize and form stable complexes with the benzene radical. In these complexes CN− is connected to the benzene radical via non-covalent interactions.

Benzonitrile: Electron affinity, excited states, and anion solvation.

We report a negative-ion photoelectron imaging study of benzonitrile and several of its hydrated, oxygenated, and homo-molecularly solvated cluster anions. The photodetachment from the unsolvated benzonitrile anion to the X̃(1)A1 state of the neutral peaks at 58 ± 5 meV. This value is assigned as the vertical detachment energy (VDE) of the valence anion and the upper bound of adiabatic electron affinity (EA) of benzonitrile. The EA of the lowest excited electronic state of benzonitrile, ã(3)A1, is determined as 3.41 ± 0.01 eV, corresponding to a 3.35 eV lower bound for the singlet-triplet splitting. The next excited state, the open-shell singlet Ã(1)A1, is found about an electron-volt above the triplet, with a VDE of 4.45 ± 0.01 eV. These results are in good agreement with ab initio calculations for neutral benzonitrile and its valence anion but do not preclude the existence of a dipole-bound state of similar energy and geometry. The step-wise and cumulative solvation energies of benzonitrile anions by several types of species were determined, including homo-molecular solvation by benzonitrile, hydration by 1-3 waters, oxygenation by 1-3 oxygen molecules, and mixed solvation by various combinations of O2, H2O, and benzonitrile. The plausible structures of the dimer anion of benzonitrile were examined using density functional theory and compared to the experimental observations. It is predicted that the dimer anion favors a stacked geometry capitalizing on the π-π interactions between the two partially charged benzonitrile moieties.

Infrared Vibrational Autodetachment Spectroscopy of Microsolvated Benzonitrile Radical Anions

Vibrational spectra of microsolvated benzonitrile radical anions (C6H5CN- -S; S = H2O and CH3OH) were measured by probing the electron detachment efficiency in the 3 microm region, representing resonance bands of autodetachment via OH stretching vibrations of the solvent molecules. The hydrogen-bonded OH band for both the cluster anions exhibited a large shift to the lower energy side with approximately 300 cm-1 compared to those for the corresponding neutral clusters. The solvent molecules are bound collinearly to the edge of the CN group of the benzonitrile anion in the cluster structures optimized with the density functional theory, in which the simulated vibrational energies are in good agreement with the observed band positions. Natural population analyses were performed for a qualitative implication in changes of solvent orientation upon electron attachment. Asymmetric band shapes depending on the vibrational modes are discussed with respect to dynamics of the autodetachment process from a theoretical aspect incorporated with density functional calculations.

On the yield of hydrated electrons at elevated temperature

In order to estimate the yield of e aq- at 200°C a pulse-radiolysis experiment was carried out with aqueous benzonitrile (BN) solutions containing 0.5 mol dm -3 ethanol. The rate coefficient of the reaction between e aq- and BN was found to increase from 2.0 × 10 10 dm 3 mol -1 s -1 at 20°C to 2.1 × 10 11 dm 3 mol -1 s -1 at 200°C. The G-value of benzonitrile anion (BN -) was evaluated from its absorption around 310 nm using an assumption that the absorption coefficient varied proportionally to the inverse of the band width. The estimated G(BN -) in a 5.1 × 10 -4 mol dm -3 BN solution was 3.1 and 3.4 mol/100 eV respectively at 20 and 200°C. The former G(BN -) is larger than G e aq at 20°C due to an effect of ethanol added to scavenge OH and H radicals, while the latter G(BN -) at 200°C is presumed to be little affected by the presence of ethanol. The result is consistent with the view that G e aq- increases significantly with temperature.

Infrared spectra and structures of carbanions—XI: Estimation of σ + constants of anionic substituents

σ + constants of H 2Cxxx- (−11.2), HNxxx- (−7.6), C 2H 5OOC-HCxxx- (−5.0), NC-HCxxx- (−5.4) and some other anionic substituents were estimated on the basis of ν CN of the corresponding benzonitrile anions and by using the correlations ν CN σ + for benzonitriles, in polar aprotic solvents.

ChemInform Abstract: PROTONATION REACTION OF THE BENZONITRILE RADICAL ANION AND ABSORPTION OF THE PRODUCT

Chemischer InformationsdienstVolume 6, Issue 24 Preparative Organic Chemistry ChemInform Abstract: PROTONATION REACTION OF THE BENZONITRILE RADICAL ANION AND ABSORPTION OF THE PRODUCT JERZY HOLCMAN, JERZY HOLCMANSearch for more papers by this authorKNUD SEHESTED, KNUD SEHESTEDSearch for more papers by this author JERZY HOLCMAN, JERZY HOLCMANSearch for more papers by this authorKNUD SEHESTED, KNUD SEHESTEDSearch for more papers by this author First published: June 17, 1975 https://doi.org/10.1002/chin.197524162AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume6, Issue24June 17, 1975 RelatedInformation

Protonation reaction of the benzonitrile radical anion and absorption of the product

The rate constant for the protonation of benzonitrile radical anions formed in pulse radiolysis of aqueous benzonitrile solutions is (3.5 ± 0.5)× 1010 dm3 mol–1 s–1. A new 270 nm absorption band is attributed to the protonated benzonitrile anion. The pK of the protonation reaction is determined to be 7.4, in good accordance with values in the literature.

Spin density calculations by modified INDO and MZDO methods. Part 1.—Organic radicals

Molecular orbital methods INDO and MZDO have been modified in an attempt to calculate spin density in large molecules where d orbitals may be included. Several such methods have been tested on the four radicals methyl, phenyl, benzonitrile anion and pyridine anion by comparing spin and charge distributions with those calculated by Pople et al. The most successful method is a modification of INDO.

Electrochemical studies of the formation and decomposition of halogenated benzonitrile anion radicals

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTElectrochemical studies of the formation and decomposition of halogenated benzonitrile anion radicalsDuane E. Bartak, Kent J. Houser, Bruce C. Rudy, and M. Dale HawleyCite this: J. Am. Chem. Soc. 1972, 94, 21, 7526–7530Publication Date (Print):October 1, 1972Publication History Published online1 May 2002Published inissue 1 October 1972https://doi.org/10.1021/ja00776a040RIGHTS & PERMISSIONSArticle Views453Altmetric-Citations39LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (614 KB) Get e-Alerts Get e-Alerts