SCF ab-initio ground state potential energy surfaces for HCN and HCN−

Pacansky, J.; Dalal, N. S.; Bagus, Paul S.

doi:10.1016/0301-0104(78)87050-5

Cited by 23 publications

(6 citation statements)

References 11 publications

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“…For two reasons, chemical catalysis represents the superior option with regard to CO 2 electroreduction. First, the generation of a CO 2 · – intermediate in an outer-sphere electron transfer is unfavorable and associated with a high reorganization energy (linear molecule vs bent radical anion). − Second, in the presence of CO 2 , typical outer-sphere reagents such as radical anions of hydrocarbons with extended π-systems (generated in aprotic media) rather undergo carboxylation via electrophilic aromatic substitution than an outer-sphere electron transfer, , whereby an exception from this trend is represented by radical anions of benzoic esters and benzonitriles (see section ). , Consequently, the CO 2 molecule is in most cases activated with a chemical catalyst, whereas redox catalysts/outer-sphere mediators are more suitable for the electroconversion of larger organic molecules. − …”

Section: Fundamentals Of Electrochemical Co2 Reductionmentioning

confidence: 99%

Homogeneously Catalyzed Electroreduction of Carbon Dioxide—Methods, Mechanisms, and Catalysts

2018

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The utilization of CO via electrochemical reduction constitutes a promising approach toward production of value-added chemicals or fuels using intermittent renewable energy sources. For this purpose, molecular electrocatalysts are frequently studied and the recent progress both in tuning of the catalytic properties and in mechanistic understanding is truly remarkable. While in earlier years research efforts were focused on complexes with rare metal centers such as Re, Ru, and Pd, the focus has recently shifted toward earth-abundant transition metals such as Mn, Fe, Co, and Ni. By application of appropriate ligands, these metals have been rendered more than competitive for CO reduction compared to the heavier homologues. In addition, the important roles of the second and outer coordination spheres in the catalytic processes have become apparent, and metal-ligand cooperativity has recently become a well-established tool for further tuning of the catalytic behavior. Surprising advances have also been made with very simple organocatalysts, although the mechanisms behind their reactivity are not yet entirely understood. Herein, the developments of the last three decades in electrocatalytic CO reduction with homogeneous catalysts are reviewed. A discussion of the underlying mechanistic principles is included along with a treatment of the experimental and computational techniques for mechanistic studies and catalyst benchmarking. Important catalyst families are discussed in detail with regard to mechanistic aspects, and recent advances in the field are highlighted.

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Section: Fundamentals Of Electrochemical Co2 Reductionmentioning

confidence: 99%

Homogeneously Catalyzed Electroreduction of Carbon Dioxide—Methods, Mechanisms, and Catalysts

2018

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“…[7][8][9] Pacansky et al, 7 on the basis of Hartree-Fock ͑HF͒ calculations, obtained a negative value of the adiabatic electron affinity ͑Ϫ1.95 and Ϫ2.09 eV, depending on the basis set used͒ for HCN and, therefore, concluded that its anion should not be stable in the gas phase since it was unlikely, in their opinion, that correlation effects would be sufficiently large to change the sign of the calculated EA. A similar conclusion was made later by Lohr 8 on the basis of HF calculations with 6-31ϩG** basis sets.…”

Section: A Anions Of Hydrogen Cyanide and Isocyanidementioning

confidence: 99%

Ab initio electronic structure of HCN− and HNC− dipole-bound anions and a description of electron loss upon tautomerization

Skurski

Gutowski

Simons

2001

The Journal of Chemical Physics

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A Drude-model approach to dispersion interactions in dipole-bound anionsThe binding of an excess electron to HCN and HNC was studied at the coupled cluster level of theory with single, double, and noniterative triple excitations and with extended basis sets to accommodate the loosely bound excess electron. The HCN molecule, with a dipole moment of 3.05 Debye, binds an electron by 10 cm Ϫ1 , whereas the HNC tautomer possesses a similar dipole moment ͑3.08 Debye͒ and binds the electron by 43 cm Ϫ1 . The electronic stability of the anionic system along the minimum energy HCN→HNC tautomerization path has been investigated, and it was concluded that the excess electron autodetaches during the tautomerization. Unusually large electron correlation energy contributions to the total electron binding energy were found and are discussed.

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“…There is significant interest in the properties of CO 2 in aqueous media. It is well-established that free molecular CO 2 cannot bind an electron as CO 2 – is predicted to be metastable with a potential energy minimum 0.4 eV above the ground state of the neutral CO 2 molecule. − In order to spectroscopically measure the properties of this unstable anionic species, early CO 2 – studies were conducted by trapping the anion in various salt matrices, such as alkali halides . Time-of-flight (TOF) mass spectrometry (MS) was used to observe direct attachment of an electron to (CO 2 ) n clusters with 2 ≤ n ≤ 6 generated from a supersonic nozzle; however, the presence of CO 2 – was not observed in this TOF MS study.…”

Section: Introductionmentioning

confidence: 99%

Energetics of CO₂^– in Aqueous Solution

McNeill

Dixon

2019

J. Phys. Chem. A

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Gas-phase and aqueous solution properties of neutral and anionic clusters of CO 2 with 3, 4, and 8 explicit H 2 O molecules are calculated at the coupled cluster (CCSD(T)) level plus a self-consistent reaction field. Anionic clusters with the radical electron density localized on the carbon of the CO 2 molecule rather than localized on the H 2 O molecules are more favorable energetically by 10−20 kcal/mol in the gas phase (ΔH gas (298 K)) and 20−30 kcal/mol in aqueous solution (ΔG aq (298 K)). The most favorable structures are those with the largest number of strong hydrogen bonds between the CO 2 − and the explicit H 2 O molecules. Adiabatic electron affinities were calculated in the gas phase and in aqueous solution for the microsolvated anion. The adiabatic electron affinity of aqueous CO 2 − is predicted to be 2.35 ± 0.08 eV and is converged with as few as 3 explicit H 2 O molecules plus a self-consistent reaction field. The EA of aqueous CO 2 is significantly greater than the aqueous solvation free energy of the electron. The vertical attachment energies to CO 2 and the vertical detachment energies from CO 2 − were calculated. The solvated CO 2 − anion is substantially bent to 135°, which requires 1.52 eV. The large energy required for bending in combination with the vertical detachment and attachment energies shows that substantial local solvent reorganization occurs on detachment or attachment of an electron to solvated CO 2 . The formation of aqueous C 2 O 4 2− from CO 2 − was also explored, and dimerization is predicted to occur.

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SCF ab-initio ground state potential energy surfaces for HCN and HCN−

Cited by 23 publications

References 11 publications

Homogeneously Catalyzed Electroreduction of Carbon Dioxide—Methods, Mechanisms, and Catalysts

Homogeneously Catalyzed Electroreduction of Carbon Dioxide—Methods, Mechanisms, and Catalysts

Ab initio electronic structure of HCN− and HNC− dipole-bound anions and a description of electron loss upon tautomerization

Energetics of CO₂^– in Aqueous Solution

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SCF ab-initio ground state potential energy surfaces for HCN and HCN−

Cited by 23 publications

References 11 publications

Homogeneously Catalyzed Electroreduction of Carbon Dioxide—Methods, Mechanisms, and Catalysts

Homogeneously Catalyzed Electroreduction of Carbon Dioxide—Methods, Mechanisms, and Catalysts

Ab initio electronic structure of HCN− and HNC− dipole-bound anions and a description of electron loss upon tautomerization

Energetics of CO2– in Aqueous Solution

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Energetics of CO₂^– in Aqueous Solution