Endre søk
RefereraExporteraLink to record
Permanent link

Direct link
Referera
Referensformat
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annet format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annet språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Solvation of carbanions in organic solvents: A test of the polarizable continuum model
KTH, Tidigare Institutioner                               , Kemi.ORCID-id: 0000-0003-2673-075X
2000 (engelsk)Inngår i: Journal of Physical Chemistry B, ISSN 1089-5647, Vol. 104, nr 42, s. 9887-9893Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

The solvation of carbanions in the solvents N,N-dimethylformamide (DMF) and tetrahydrofuran (THF) has been analyzed on the basis of experimental and theoretical data. Experimental solvation energies are obtained from present and previously reported electrochemical measurements of reduction potentials of the corresponding radicals. Theoretical solvation energies are obtained from quantum chemical calculations using the polarizable continuum model (PCM). It is found that the solvation energy is relatively independent of molecular size and structure for the saturated carbanions. This indicates that the negative charge is strongly localized to the anionic carbon. The conjugated carbanions have considerably lower absolute solvation energies (\ DeltaG degrees (sol)\) than the saturated carbanions. This is a consequence of the strong delocalization of the negative charge in the former group. The propargyl anion is also found to have a surprisingly low absolute solvation energy. However, high-level quantum chemical calculations show that the electronic structure has large contributions from two different resonance structures, CH=CCH2- and -CH=C=CH2, which results in a significant charge delocalization. There is good agreement between calculated and experimental solvation energies for both the conjugated and nonconjugated primary anions. However, the PCM method consistently underestimates the absolute solvation energies of the secondary and tertiary carbanions. This is attributed to an insufficient treatment of first-layer solvation effects in the method. According to the experimental measurements, the absolute solvation energies are on average 2-3 kcal mol(-1) lower in THF than in DMF. The theoretical data indicate a considerably larger solvent effect, 7-10 kcal mol(-1). The discrepancy between theory and experiment may partly be attributed to the use of a supporting electrolyte in the measurements, but the main cause seems to be that the short-range interaction tendencies of the solvent cannot be Fully characterized by its dielectric constant.

sted, utgiver, år, opplag, sider
2000. Vol. 104, nr 42, s. 9887-9893
Emneord [en]
free-energies, gas-phase, reduction potentials, aqueous-solution, ab-initio, radicals, photoinjection, inversion, anions, ion
Identifikatorer
URN: urn:nbn:se:kth:diva-20139ISI: 000165077600018OAI: oai:DiVA.org:kth-20139DiVA, id: diva2:338832
Merknad
QC 20100525Tilgjengelig fra: 2010-08-10 Laget: 2010-08-10bibliografisk kontrollert

Open Access i DiVA

Fulltekst mangler i DiVA

Personposter BETA

Brinck, Tore

Søk i DiVA

Av forfatter/redaktør
Brinck, Tore
Av organisasjonen

Søk utenfor DiVA

GoogleGoogle Scholar

urn-nbn

Altmetric

urn-nbn
Totalt: 41 treff
RefereraExporteraLink to record
Permanent link

Direct link
Referera
Referensformat
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annet format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annet språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf