Multinuclear ENDOR study of trapped electrons in the polycrystalline cesium hexamethylhexacyclen sodide, Cs+(HMHCY).cntdot.Na-

Ellaboudy, Ahmed S.; Bender, Christopher J.; Kim, Jineun; Shin, Dae Ho; Kuchenmeister, M. E.; Babcock, Gerald T.; Dye, James

doi:10.1021/ja00007a001

Cited by 14 publications

(10 citation statements)

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“…The results of our ESEEM analysis for the "stronger" coupled cesium ion differ with those reported for recent ENDOR studies of Cs+(HMHCY)Na - [10]. In this ENDOR work, a pair of lines split by 0.31 MHz about the 133Cs Larmor frequency was observed.…”

Section: Resultscontrasting

confidence: 97%

“…Because a large amount of unpaired electron spin density ii present at the Cs cation closest to the proposed Na-vacancy, it is reasonable to assume that couplings to the nitrogen nuclei of the HMHCY complexant should be observed. This idea is supported by previous ENDOR studies [10] where proton hyperfine couplings as large as 4.0 MHz were assigned to the methyl protons of the HMHCY complexant based on isotopic substitution work. Additional, weak ESEEM frequency components were observed at 3.4, 4.2, and 4.6 MHz and may arise from hyperfine coupling to 14N or 23Na nuclei.…”

Section: Resultssupporting

confidence: 67%

“…Previous cw-EPR and cw-ENDOR studies of Cs+(HMHCY)Na -have provided valuable information toward reaching this goal [10]. The X-band cw-EPR spectrum of this material shows a large hyperfine splitting by a single Cs +, with the isotropic or Fermi contact portion of the coupling being 98 G. Parallel ENDOR studies showed additional magnetic couplings between the unpaired electron spin and protons of the complexant, 23Na and 133Cs nuclei.…”

Section: Lntroductionmentioning

confidence: 84%

“…The cw-EPR spectrum of Cs+(HMHCY)Na -has been reported [10]. The spectrum has eight major peaks split about g = 1.98 that have been attributed to hyperfine coupling between the trapped electron and its complexed Cs + counterion 4.26 A away.…”

Section: Resultsmentioning

confidence: 99%

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Pulsed EPR studies of polycrystalline cesium hexamethyl hexacyclen sodide

1992

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The electron spin echo envelope modulation (ESEEM) technique of pulsed EPR spectroscopy has been used to measure weak 133Cs hyperfine couplings to trapped electrons in polycrystalline cesium hexamethyl hexacyclen sodide. Two magnetically distinct groups of weakly coupled 133Cs nuclei were found -one with an isotropic electron-nuclear hyperfine (Fermi contact) coupling of 0.34 MHz and the other with a contact coupling less than 0.1 MHz. Analysis of these data, by computer simulation, shows that the number of Cs nuclei that give rise to these interactions and their distance from the paramagnetic center is consistent with the hypothesis that the trapped electrons occupy vacant anion sites. The results indicate that the spread of unpaired electron spin density, along the axis formed by the "contact ion pair," may be greater than that in the plane perpendicular to this axis. lntroductionElectrides are a class of solids that consist of complexed metal cations and trapped electrons in a well-defined structural arrangement. Asa class, electrides represent extremes where trapped electrons are localized at one limit and are able to move from site to site at the other. The degree of localization of trapped electrons depends markedly on the metal cation and complexant used for the synthesis. For cesium 18-crown-6 electride, Cs+(18C6)2 e-, cesium cations are complexed by two 18C6 crown ethers, and the trapped electrons are localized with separation distances of 8-10 ,/k [1,2]. A much different situation is found for K+(C222)e -, where strong inter-electron interactions have been observed [3]. Possible uses of these compounds for the doping of organic semiconductors [4], andas chemical reagents for the preparation of small metal particles [5] have been reported. Because their chemical and physical properties depend on the nature of their trapped electrons, it is important that the details of these trapping sites be understood.

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Section: Resultscontrasting

confidence: 97%

Section: Resultssupporting

confidence: 67%

Section: Lntroductionmentioning

confidence: 84%

Section: Resultsmentioning

confidence: 99%

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Pulsed EPR studies of polycrystalline cesium hexamethyl hexacyclen sodide

1992

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“…A most direct experimental method will be a charge-density mapping by X-ray diffraction (XRD) using the maximum entropy method combined with the Rietveld analysis. This method was carried out for another electride 12CaO·7Al 2 O 3 . Unfortunately, such measurements are unlikely at present because the density of interstitial electrons is too low to be probed by XRD .…”

mentioning

confidence: 99%

Evidence for Anionic Excess Electrons in a Quasi-Two-Dimensional Ca₂N Electride by Angle-Resolved Photoemission Spectroscopy

Kang

Kim

et al. 2016

J. Am. Chem. Soc.

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Angle-resolved photoemission spectroscopy (ARPES) study of a layered electride Ca2N was carried out to reveal its quasi-two-dimensional electronic structure. The band dispersions and the Fermi-surface map are consistent with the density functional theory results except for a chemical potential shift that may originate from the high reactivity of surface excess electrons. Thus, the existence of anionic excess electrons in the interlayer region of Ca2N is strongly supported by ARPES.

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Verzerrte Moleküle: Störungsdesign, Synthesen und Strukturen

Bock

Ruppert²,

Näther³

et al. 1992

Angewandte Chemie

157

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Die Struktur eines Molekiils kann sich mit seiner Energie und damit seiner Elektronenverteilung innerhalb der Zeitskala dynamischer Relaxation betrlchtlich andern. Ausgehend von Vergleichen geeigneter MeDdaten verwandter Verbindungen und unterstiitzt durch quantenchemische Naherungsrechnungen lassen sich daher ladungsgestorte undloder raumlich iiberfiillte Molekiile entwerfen, deren Synthese, Handhabung und Strukturbestimmung -unter oft extremen und vor allem weitgehend aprotischen Bedingungen -zu manchen Uberraschungen fuhrt. Dabei werden neue Strukturprinzipien deutlich und altbekannte bestatigt. So enthalten einige der bei ultraschallgeforderter Reduktion ungesattigter Kohlenwasserstoffe mit Natriummetall entstehenden Kontaktionenaggregate von Molekiilanionen DibenzolnatriumSandwich-Einheiten. Vicinale Dimethylaminosubstituenten bewirken wie die isoelektronischen Isopropylgruppen sterische Uberfiillung und erleichtern die Oxidation zu Molekiilkationen durch energetisch giinstige Delokalisierung der erzeugten positiven Ladung. Molekiile und Molekiilionen, in denen sich eine gerade Anzahl von .n-Elektronen iiber ein ungeradzahliges cr-Geriist verteilt, bilden bevorzugt Cyanin-Untereinheiten aus; dies belegen auch die erstmals isolierten Salze von Ethen-Dikationen und Ethen-Dianionen mit C-C-Einfachbindung und gegeneinander verdrillten Molekiilhalften. -Insgesamt konnten in zwei Jahren iiber 50 unbekannte Strukturen bestimmt werden. Aus ihnen haben wir vie1 gelernt, insbesondere iiber Elektronentransfer und Kontaktionenpaar-Bildung in aprotischen Losungen. Wir mu& ten aber auch erkennen, daI3 eine Beantwortung vieler Fragen -darunter vor allem ,,was kristallisiert wie und warum?" -noch in weiter Ferne liegt. Eigentlich ist alles vie1 komplizierterVorwort einer Frankfurter Doktorarbeit Ausgangspunkt : Strukturabschatzungen aus MeBdaten und naherungsweisen Energieh yperflachen-BerechnungenAuch der iiberwiegend praparativ engagierte Chemiker profitiert erheblich, wenn er seine Spektren zusatzlich unter dem Gesichtspunkt ,,Molekiilzustands-Fingerabdriicke" betrachtet"]. Je ein Beispiel fur Gasphase und Losung sollen Vorgehen und Erkenntnisgewinn verdeutlichen. Die Struktur von H,CS-CEC-SCH, in der GasphaseDie Gasphasenthermolyse von Bis(methy1thio)cyclobuten-l,2-dion bei 720 K verlauft nach Photoelektronen(PE)-

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Multinuclear ENDOR study of trapped electrons in the polycrystalline cesium hexamethylhexacyclen sodide, Cs+(HMHCY).cntdot.Na-

Cited by 14 publications

References 2 publications

Pulsed EPR studies of polycrystalline cesium hexamethyl hexacyclen sodide

Pulsed EPR studies of polycrystalline cesium hexamethyl hexacyclen sodide

Evidence for Anionic Excess Electrons in a Quasi-Two-Dimensional Ca₂N Electride by Angle-Resolved Photoemission Spectroscopy

Verzerrte Moleküle: Störungsdesign, Synthesen und Strukturen

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Multinuclear ENDOR study of trapped electrons in the polycrystalline cesium hexamethylhexacyclen sodide, Cs+(HMHCY).cntdot.Na-

Cited by 14 publications

References 2 publications

Pulsed EPR studies of polycrystalline cesium hexamethyl hexacyclen sodide

Pulsed EPR studies of polycrystalline cesium hexamethyl hexacyclen sodide

Evidence for Anionic Excess Electrons in a Quasi-Two-Dimensional Ca2N Electride by Angle-Resolved Photoemission Spectroscopy

Verzerrte Moleküle: Störungsdesign, Synthesen und Strukturen

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Product

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Evidence for Anionic Excess Electrons in a Quasi-Two-Dimensional Ca₂N Electride by Angle-Resolved Photoemission Spectroscopy