Intramolecular reorientations and the effects of thermal history and hydrogen bonding in four closely related organic molecular solids

Aronson, M. C.; Beckmann, Peter A.; Ross, B. D.; Tan, Swee Lian

doi:10.1016/0301-0104(81)87010-3

Cited by 15 publications

(8 citation statements)

References 13 publications

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“…For both O)T<1 mdo)r>l, the ratio /FK^-^CC~^ 1 as /3 and S-> 1 and-^UTT as ^ and 5-^0. For a given substance, or at least a given sample with a specific thermal history [146,147], 5 or /3 will usually be constant in which case it is not possible to distinguish between /pj. and /^c ^^ ^ ^^R Zeeman study unless the frequency dependence is observed.…”

Section: Fuoss-kirkwood (Fk)mentioning

confidence: 99%

Spectral densities and nuclear spin relaxation in solids

1988

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Section: Fuoss-kirkwood (Fk)mentioning

confidence: 99%

Spectral densities and nuclear spin relaxation in solids

1988

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“…For a 2,6-ditert-butyl arrangement, dielectric relaxation (26), hydroxyl stretching frequencies (27), ultraviolet absorption (28), ' H spin-lattice relaxation rates (27,29), X-ray diffraction results (30,31), and hyperfine splittings in a cation radical (32) are all consistent with a substantial coplanar preference of the hydroxyl group.…”

Section: Spectrnl Analysesmentioning

confidence: 89%

The intramolecular equilibrium in 2-tert-butylphenol and some derivatives. An anomalous indicating steric distortion

Schaefer¹,

Sebastian²,

Salman³

1984

Can. J. Chem.

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. Can. J. Chem. 62, 113 (1984). The 'H nmr spectral parameters in dilute carbon tetrachloride solution arc reported for 2-tert-butylphenol, as obtained by decoupling of the sidechain protons. Long-range couplings between hydroxyl and ring protons are also reported for five derivatives of 2-terr-butylphenol. In the cis conformer of 2-tert-butylphenol an anomalous ' J ? '~- ' occurs, most likely as a consequence of a significant distortion of the COH geometry. Such an anomaly, which leads to an incorrect estimate of the cis-trans equilibrium constant, does not occur in other alkyl phenols, for example, in 2-tert-butyl-6-methylphenol. The coupling constant data provide no evidence for out-of-plane conformational preferences of the hydroxyl group in these compounds.TED SCHAEFER, RUDY SEBASTIAN et SALMAN R. SALMAN. Can. J. Chem. 62, 113 (1984). On rapporte les paramktres spectraux en rmn du 'H obtenus en dkcouplant les protons de la chaine lattrale du tert-butyl-2 phenol en solution dans le tttrachlorure de carbone. On rapporte Cgalement les couplages B longue distance entre le groupe hydroxyle et les protons du cycle de cinq dtrivCs du tert-butyl-2 phtnol. Dans le conformkre cis du tert-butyl-2 phtnol, il se produit un 5~: H ' H -5 anomal qui serait une consCquence d'une dtformation importante de la gComCtrie du groupe COH. Une telle anomalie, qui conduit B une tvaluation incorrecte de la constante d'tquilibre cis-trar~s, ne se produit pas dans les autres phCnols alkylCs: comme par exemple avec le tert-butyl-2 mCthyl-6 phCnol. Les donnCes de constante de couplage n'apportent pas la preuve d'une prCfCrence conformationnelle hors du plan du groupe hydroxyle de ces composts.[Traduit par le journal]

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“…The two t-butyl groups reorient at the same rate as their constituent methyls and thus a single maximum in R versus Tis observed (i.e. wt, -1 occurs only once), as discussed by Beckmann (1981).…”

mentioning

confidence: 81%

“…There are several important points here. Firstly, this data cannot be fitted with a variety of standard spectral densities (Beckmann 1981), whereas the one presented here is quite successful. Secondly, the ratio of the high-to low-temperature slopes of In R versus T-' gives y independently for each frequency and that the additional prediction R CC l/w'+Yfor wt, S-1 is also correct for the two frequencies is an additional check on the spectral density.…”

mentioning

confidence: 91%

“…Firstly, since dipoledipole interactions are responsible for the relaxation, both single and double spin flips are involved and the combination j ( t c , w) + 4 j(tc, 2w) enters into R. Secondly, the methyl reorientation is superimposed on t-butyl reorientation and this leads to terms in t,/2 as well as tc since the superposition frequency t;' + t ; ' = 2t;' enters the relaxation as well as just ti' (Beckmann 1980). The detailed calculation of R is given by Beckmann (1981) and the result is j ( t c , w ) + 4 j ( t , , 2 w ) + j…”

mentioning

confidence: 99%

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A general NMR spectral density and its experimental verification

Albano

Beckmann

Carrington

et al. 1983

J. Phys. C: Solid State Phys.

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We develop a new general spectral density for use in interpreting nuclear spinlattice relaxation measurements in molecular solids where molecular and/or intramolecular reorientation is responsible for the relaxation. We show that the simplest case of the general theory fits both the temperature and Larmor frequency dependence of some very complicated relaxation measurements which could not be previously fitted using several standard spectral densities. The relationship of the spectral density to a distribution of molecular potentials is briefly outlined.

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Intramolecular reorientations and the effects of thermal history and hydrogen bonding in four closely related organic molecular solids

Cited by 15 publications

References 13 publications

Spectral densities and nuclear spin relaxation in solids

Spectral densities and nuclear spin relaxation in solids

The intramolecular equilibrium in 2-tert-butylphenol and some derivatives. An anomalous indicating steric distortion

A general NMR spectral density and its experimental verification

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