Vibronic Interaction in Potassium o-Xylenide

Tuttle, Thomas R.

doi:10.1021/ja00873a048

Cited by 17 publications

(4 citation statements)

References 2 publications

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“…Orbital mixing. Coupling constants of cr-protons in a few hydrocarbon n-radicals having a near-degenerate ground state are known to exhibit a temperature dependence comparable to that observed for 10 [6] 171. In such n-radicals, thermal mixing of two one readily concludes that the n-spin population in IQ is distributed according to (@, )-, i.e.…”

Section: Fi)mentioning

confidence: 81%

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Unusual Features in the ESR. Spectra of 1, 6‐Methano[10] annulene Radical Anion. A modified mcconnell equation for non‐planar π‐radicals

Gerson

Müllen

Vogel

1971

Helvetica Chimica Acta

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Summury. SSR. spectra of the radical anions of 1,6-methano[lO]annulcnc (1) and its 2,5,7, 0tetradeuterio derivative I1 are reported for a temperature range of over 100". The abnormally small magnitudes of the a-proton coupling constants are attributed to thc deviation of the ten-Inernbered n-perimeter from planarity; an cxtension of the McConneZZ equation is proposed to achieve agreement between theory and experiment. It is suggested that the marked temperaturedependence of the ESR. spectra arises from slight changes in geometry which for Ie should have a more pronounced cffect on the a-proton coupling constants than for planar n-radicals.Several years ago, we reported the ESR. data for the radical anions of 3,6methano[lO]annulene (I) and some of this deuterio derivatives [l]. The coupling constants of the cl-protons3) in 10 were found to deviate strongly from the expected values. Later investigations also revealed that the ESR. spectrum of 10, which was previously observed at -70", is markedly temperature dependent.In the present paper we report the ESR. data for 10 and its 2,5,7,10-tetradeuterio derivative 110 over a range of more than 100°C.4) We also discuss the effect of nonplanarity of the ten-membered perimeter on the a-proton coupling constants and attempt to rationalize their temperature dependence in terms of changes in geometry.Results. -Radical anion of l,6-methano[10]annulene (I). Fig. 1 illustrates the effect of temperature variation on the ESR. spectra of IQ in 1,2-dimethoxyethane (DME) with Na@ as counter-ion.5) Before the observed changes in the spectra are l)

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Section: Fi)mentioning

confidence: 81%

“…The plots of I U H (~) 1, I U H (~) 1, and 1 abHp j vs. temperature ( T ) are presented in Radical anion of 2,5,7,lO-tetradeuterio-7, 6 Fig. 3 shows the ESR.…”

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confidence: 99%

Unusual Features in the ESR. Spectra of 1, 6‐Methano[10] annulene Radical Anion. A modified mcconnell equation for non‐planar π‐radicals

Gerson

Müllen

Vogel

1971

Helvetica Chimica Acta

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“…Depending on the catalyst used, methyl branches are incorporated into synthetic Fischer–Tropsch waxes, , thus changing physical properties. A class of “microcrystalline” wax also contains a significant branched chain component. − Conversion of normal paraffin feedstocks into a desirable lower melting lubricant component is achieved by zeolite-mediated catalysis via creation of iso -branched products . Addition of a branched chain component to a waxy fuel mixture may also act as a crystal growth modifier to retard the lateral crystal plate size in cold weather …”

Section: Introductionmentioning

confidence: 99%

Rectangular Chain Packing of Methyl-Branched Paraffins: Persistence of an Interchain Interaction and Forms of Disorder

et al. 2011

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The rectangular crystal packing of methyl-branched paraffins in their orthorhombic forms is studied systematically by electron diffraction to show that, irrespective of branch position on the chain, a close interaction of chain double rows occurs, placing the branch in the space between two chain ends. If the chain branches occur near the ends, the structure can slowly rearrange into a true bilayer. If the branch occurs near the center, then there are a large number of intermediate "nematocrystalline" disordered forms that are possible before the final ordered layered packing.

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“…this radical undergoes a dynamical Jahn-Teller effect [2][3][4]. Substitution of an alkyl group in a benzene negative ion removes this degeneracy, but recent electron spin resonance experiments [5][6][7] have shown that the energy splitting of the two electronic states is relatively small and that a dynamical vibronic coupling consequently still exists. The ordinary Born-Oppenheimer potential surfaces and wave functions still play a fundamental role in the theory of the coupled vibrational-electronic motion [8] so that the understanding of, say, the spin resonance spectra of the substituted ions involves two main steps : (1) the computation of the energies and spin density distributions of the two initially degenerate states and (2) the calculation of the coupling of these two electronic states by the molecule's nuclear motions.…”

Section: Introductionmentioning

confidence: 99%

Spin densities in hydrocarbon ions with degenerate ground states

Hobey

1964

Molecular Physics

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In dealing theoretically with the effects of vibronic interactions in substituted benzene mononegative radical-ions it is useful to know the spin density distributions in the degenerate ground level of unsubstituted benzene anions. A configuration interaction theory is developed for hydrocarbon anions with degenerate ground states and applied to the benzene anion problem. The results show negative spin densities on atoms having zero spin density in the Htickel approximation.

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Vibronic Interaction in Potassium o-Xylenide

Cited by 17 publications

References 2 publications

Unusual Features in the ESR. Spectra of 1, 6‐Methano[10] annulene Radical Anion. A modified mcconnell equation for non‐planar π‐radicals

Unusual Features in the ESR. Spectra of 1, 6‐Methano[10] annulene Radical Anion. A modified mcconnell equation for non‐planar π‐radicals

Rectangular Chain Packing of Methyl-Branched Paraffins: Persistence of an Interchain Interaction and Forms of Disorder

Spin densities in hydrocarbon ions with degenerate ground states

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