Structure and photodecomposition reactions of cations of cyclopentane, cyclohexane, cyclic olefines and dienes inγ-irradiated frozen solutions of CF3CCl3. An ESR study

Tabata, Masayoshi; Lund, A.

doi:10.1016/0301-0104(83)85204-5

Cited by 72 publications

(23 citation statements)

References 12 publications

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“…The radical cation 9 . of cyclohexa-1,4-diene exhibits an extremely large coupling constant, 6.8 [15] (or 6.71 mT [16]), of the four CH 2 b-protons, which is similar to the a value, 6.60 mT, of two such protons in 4f . .…”

Section: Scheme 2 Schemementioning

confidence: 66%

Influence of Ring Annelation on the Mode Selectivity of the Ionized Diazabicycloheptenes and Corresponding Housanes: An ESR and ENDOR Study

Gerson

Şahin

2001

HCA

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Dedicated to Professor Edgar Heilbronner on the occasion of his 80th birthdayThe tricyclic azoalkanes, (1a,4a,4aa,7aa)-4,4a,5,6,7,7a-hexahydro-1,4,8,8-tetramethyl-1,4-methano-1H-cyclopenta[d]pyridazine (1c), (1a,4a,4aa,6aa)-4,4a,5,6,6a-pentahydro-1,4,7,7-tetramethyl-1,4-methano-1H-cyclobuta[d]pyridazine (1d), (1a,4a,4aa,6aa)-4,4a,6a-trihydro-1,4,7,7-tetramethyl-1,4-methano-1H-cyclobuta[d]-pyridazine (1e), and (1a,4a,4aa,5aa)-4,4a,5,5a-tetrahydro-1,4,6,6-tetramethyl-1,4-methano-1H-cyclopropa[d]-pyridazine (1f), as well as the corresponding housanes, the 2,3,3,4-tetramethyl-substituted tricyclo[3.3.0.0 2,4 ]octane (2c), tricyclo[3.2.0.0 2,4 ]heptane (2d), and tricyclo[3.2.0.0 2,4 ]hept-6-ene (2e), were subjected to g-irradiation in Freon matrices. The reaction products were identified with the use of ESR and, in part, ENDOR spectroscopy. As expected, the strain on the C-framework increases on going from the cyclopentane-annelated azoalkanes and housanes (1c and 2c) to those annelated by cyclobutane (1d and 2d), by cyclobutene (1e and 2e), and by cyclopropane (1f). Accordingly, the products obtained from 1c and 2c in all three Freons used, CFCl 3 , CF 3 CCl 3 , and CF 2 ClCFCl 2 , were the radical cations 3c . and 2c . of 2,3,4,4-tetramethylbicyclo[3.3.0]oct-2-ene and 2,3,3,4-tetramethylbicyclo[3.3.0]octane-2,4-diyl, respectively. In CFCl 3 and CF 3 CCl 3 matrices, 1d and 2d yielded analogous products, namely the radical cations 3d . and 2d . of 2,3,4,4-tetramethylbicyclo[3.2.0]hept-2-ene and 2,3,3,4-tetramethylbicyclo[3.2.0]heptane-2,4-diyl. The radical cations 3c . and 3d . and 2c . and 2d . correspond to their non-annelated counterparts 3a . and 3b . , and 2a . and 2b . generated previously under the same conditions from 2,3-diazabicyclo[2.2.1]hept-2-ene (1a) and bicyclo[2.1.0]pentane (2a), as well as from their 1,4-dimethyl derivatives (1b and 2b). However, in a CF 2 ClCFCl 2 matrix, both 1d and 2d gave the radical cation 4d . of 2,3,3,4-tetramethylcyclohepta-1,4-diene. Starting from 1e and 2e, the radical cations 4e . and 4e' . of the isomeric 1,2,7,7-and 1,6,7,7-tetramethylcyclohepta-1,3,5-trienes appeared as the corresponding products, while 1f was converted into the radical cation 4f . of 1,5,6,6-tetramethylcyclohexa-1,4-diene which readily lost a proton to yield the corresponding cyclohexadienyl radical 4f . . Reaction mechanisms leading to the pertinent radical cations are discussed.Introduction. ± In a previous work, ionization of 2,3-diazabicyclo[2.2.1]hept-2-ene (1a) and the corresponding bicyclo[2.1.0]pentane (housane; 2a), as well as of their 1,4-dimethyl derivatives 1b and 2b, respectively, was carried out by g-irradiation in Freon matrices, and the resulting radical cations were studied by ESR spectroscopy [1]. Whereas the azoalkanes 1a and 1b yielded the radical cations of cyclopentene (3a) and its 1,3-dimethyl derivative 3b, respectively, cyclopentane-1,3-diyl radical cations were obtained by starting from the corresponding housanes 2a and 2b (Scheme 1).Despite a considerable weakening of the cent...

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Section: Scheme 2 Schemementioning

confidence: 66%

Influence of Ring Annelation on the Mode Selectivity of the Ionized Diazabicycloheptenes and Corresponding Housanes: An ESR and ENDOR Study

Gerson

Şahin

2001

HCA

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“…Previously we reported19, 20, 27–31, 33, 34, 43, 50 that the g value of not only aromatic but also aliphatic poly(acetylene)s, such as poly(alkylpropiolate)s, called poly(acetyleneester)s can be used to deduce the reasonable geometrical conformations, that is, cis form or trans form, when one hetero atom such as an O, N, or S is involved within the side chain of the polymer. Such a hetero atom is reported to have a relatively large spin orbit coupling constant (δ)51, 52 compared with the case of the hydrocarbon radicals. The hetero atom is expected to increase the observed g value, that is, to shift the center of the ESR spectrum to a fairly lower magnetic field, especially in the case of the cis form, although in the case of the trans form such a shift is not largely expected because in the trans form such effective decoupling on the magnetic interaction dose not work between the side chain and the planar trans main‐chain 19, 20, 33, 34, 43, 46.…”

Section: Resultsmentioning

confidence: 99%

Origin of the color of π‐conjugated columnar polymers: Poly(p‐n‐octylthiophenyl)acetylene prepared using a [Rh(norbornadiene)Cl]₂ catalyst

Huang

Tabata

Mawatari

et al. 2005

J. Polym. Sci. A Polym. Chem.

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Highly stereospecific polymerization of a novel sulfur containing aromatic acetylenes, that is, (p-n-octylthiophenyl)acetylene (pOctSPA), was successfully performed using the Rh complex, [Rh(norbornadiene)Cl] 2 -TEA, catalyst in the presence of various solvents under mild conditions. The resulting polymers were characterized in detail by 1 H NMR, ESR, laser Raman, diffuse reflective UV-Vis (DRUV-Vis), and wide angle X-ray diffraction methods. The data showed that the resulting polymers bear cis-transoid form, which can induce the cis-to-trans isomerization when the cis polymers are subjected to pressure at room temperature under vacuum, breaking rotationally the cis C¼ ¼C bonds in the main-chain giving two kinds of -radicals, the so-called cis radical and trans radical as the origin of a polymer magnet like a novel spin glass material. Further, the resulting cis poly(acetylene)s were found to have a helical main-chain, which is packed in pseudohexagonal crystal called -conjugated columnar or nano -conjugated columnar as a novel color controllable material.

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“…ESR parameters of poly(1), poly(2), and poly(3) are summarized in Table 2. In addition, the g value of the observed radicals was used to deduce the geometrical structures, i.e., cis form or trans form, when one hetero atom such as N, S, and I is involved within the side-chain of the polyacetylene molecules [1e, [21][22][23]. Such a hetero atom has a relatively large spin orbit coupling constant,  compared with that of the hydrocarbon atoms [22][23][24].…”

Section: Esr Spectramentioning

confidence: 99%

Cis and trans radicals generated in helical poly(propargyl acetate)s prepared using a [Rh(norbornadiene)Cl]2 catalyst

Yoshida

Mawatari

Seki

et al. 2011

Polymer

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The poly(propargyl acetate) (A) having a helical cis-transoid structure was stereospecifically prepared using the Rh complex catalyst, [Rh(norbornadiene)Cl] 2 , in MeOH or NEt 3 solvent at room temperature in moderated yield. Electron spin resonance (ESR) analysis of the polymer revealed the formation of the cis (B) and trans (C) *Manuscript Click here to view linked References radicals which were produced through the thermal rotational scission of the helical cis C=C bonds in the main-chain during the polymerization. The spatial and geometrical structure was successfully deduced using the two analogues polymers in which either methyl or methylene group is deuterated, by the aide of computer simulation of the observed ESR spectra together with the calculation of spin density of the two radicals.

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Structure and photodecomposition reactions of cations of cyclopentane, cyclohexane, cyclic olefines and dienes inγ-irradiated frozen solutions of CF3CCl3. An ESR study

Cited by 72 publications

References 12 publications

Influence of Ring Annelation on the Mode Selectivity of the Ionized Diazabicycloheptenes and Corresponding Housanes: An ESR and ENDOR Study

Influence of Ring Annelation on the Mode Selectivity of the Ionized Diazabicycloheptenes and Corresponding Housanes: An ESR and ENDOR Study

Origin of the color of π‐conjugated columnar polymers: Poly(p‐n‐octylthiophenyl)acetylene prepared using a [Rh(norbornadiene)Cl]₂ catalyst

Cis and trans radicals generated in helical poly(propargyl acetate)s prepared using a [Rh(norbornadiene)Cl]2 catalyst

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Structure and photodecomposition reactions of cations of cyclopentane, cyclohexane, cyclic olefines and dienes inγ-irradiated frozen solutions of CF3CCl3. An ESR study

Cited by 72 publications

References 12 publications

Influence of Ring Annelation on the Mode Selectivity of the Ionized Diazabicycloheptenes and Corresponding Housanes: An ESR and ENDOR Study

Influence of Ring Annelation on the Mode Selectivity of the Ionized Diazabicycloheptenes and Corresponding Housanes: An ESR and ENDOR Study

Origin of the color of π‐conjugated columnar polymers: Poly(p‐n‐octylthiophenyl)acetylene prepared using a [Rh(norbornadiene)Cl]2 catalyst

Cis and trans radicals generated in helical poly(propargyl acetate)s prepared using a [Rh(norbornadiene)Cl]2 catalyst

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Origin of the color of π‐conjugated columnar polymers: Poly(p‐n‐octylthiophenyl)acetylene prepared using a [Rh(norbornadiene)Cl]₂ catalyst