The use of partially restricted molecular orbitals to investigate transmission mechanisms of spin–spin coupling constants. III—an INDO study of long‐range FH couplings in fluorinated derivatives of toluene

Facelli, Julio C.; Giribet, C. G.; Contreras, Rubén H.

doi:10.1002/mrc.1270190306

Cited by 20 publications

(4 citation statements)

References 21 publications

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“…In other words, there was no significant coupling, this number being a consequence of the least-squares analysis procedure. Because the internal barrier to rotation in benzaldehyde in solution is greater than 30 kJ/mol (27)(28)(29)(30)(31) (32,34). Using the factor of 0.52 above, 'J(H,C) in acetophenone follows as 0.22 Hz, as observed (Table 1).…”

Section: Comparisons With "J(hcho) In Benzaldehydementioning

confidence: 60%

“…When no off-diagonal Fock matrix elements are neglected (3,12,25,26) and no orbitals are restricted (3,12,27), the results for 6~(~, C ) indicate a finite value at 0 = 0" and that its magnitude changes very little as 0 goes towards 90" (column A).2 Qualitatively, the computed increase in magnitude of 0.07 Hz agrees with the -0.14 Hz observed in 2,6-dichloroacetophenone. The finite computed value at 0" then arises from an inadequacy of the INDO MO parameterization.…”

Section: Indo Mo Fpt Computationsmentioning

confidence: 99%

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The carbonyl group as a reluctant transmitter of hyperconjugative or σ–π spin–spin coupling interactions in derivatives of benzaldehyde, acetophenone, and benzophenone

Schaefer¹,

Peeling²,

Penner³

et al. 1986

Can. J. Chem.

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Unlike their counterparts in anisole or toluene derivatives, the six-bond spin-spin coupling constants between para ring protons or 19F nuclei and protons or 13c nuclei in the sidechain of derivatives of benzaldehyde, acetophenone, and benzophenone can apparently contain components of opposite sign, at least for the fluorine derivatives. The u-7i components are much smaller in magnitude than in toluene derivatives, leading to very small or unobservable coupling constants. Consequently they are of limited use in conformational analysis. INDO MO FPT computations and their modifications are examined as to the reasons for the small o-TI magnitudes. Although the spin polarizability of the 2pz orbital on oxygen appears to play an important role in the transmission of nuclear spin state information, the computations do not account for a "F coupling mechanism that appears to be significant for planar conformations. On the other hand, spin-spin coupling constants over five formal bonds to meta protons are sizeable and stereospecific.TED SCHAEFER, JAMES PEELING, GLENN H. PENNER et ALBERTA LEMIRE. Can. J. Chem. 64, 1859 (1986).Contrairement leurs contreparties dans les dCrivCs de l'anisole ou du toluene, les constantes de couplage spin-spin a travers six liaisons, entre les protons du cycle en position para ou les noyaux de I9F et les protons ou les noyaux de I3C de la chaine laterale des dCrivCs du benzaldehyde, de I'acCtophCnone et de la benzophCnone peuvent apparernment contenir des composants de signes opposes, au moins dans les derivCs fluores. Les constituants a-7i ont une intensit6 infkrieure a celle des dCriv6s du toluene conduisant ainsi a des constantes de couplage tr&s faibles qu'on ne peut observer. En consequence, ces constantes sont trbs peu utiles dans l'analyse conformationnelle. On a utiIisC des calculs INDO OM FPT ainsi que leurs modifications pour dCterminer les causes des faibles intensitks des constituants cr-TI. Bien que la polarisabilitk du spin de l'orbitale 2pz de I'oxygkne semble jouer un r6le important dans la transmission de I'information sur 1'Ctat du spin nuclkaire, les calculs ne tiennent pas compte du mCcanisme de couplage du 19F qui semble Ctre important dans les conformations planes. Par ailleurs, les constantes de couplage spin-spin a travers cinq liaisons formelles par rapport aux protons en position meta sont quantifiables et stCrCospCcifiques.[Traduit par la revue]

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Section: Comparisons With "J(hcho) In Benzaldehydementioning

confidence: 60%

Section: Indo Mo Fpt Computationsmentioning

confidence: 99%

The carbonyl group as a reluctant transmitter of hyperconjugative or σ–π spin–spin coupling interactions in derivatives of benzaldehyde, acetophenone, and benzophenone

Schaefer¹,

Peeling²,

Penner³

et al. 1986

Can. J. Chem.

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“…[28] To meet this goal, the Utah EPHTN has data sharing agreements with nine state agencies. The data stores are disparate and heterogeneous and range from small Microsoft Access datasets to data stored in mainframe legacy systems both within and outside the health department information system enterprise.…”

Section: Discussionmentioning

confidence: 99%

“…Utah is one of 19 states in the United States funded to develop an Environmental Public Health Tracking Network (EPHTN) to monitor and measure health indicators related to environmental exposures, including asthma, birth defects, childhood lead poisoning, and cancer. [ 28 ] To meet this goal, the Utah EPHTN has data sharing agreements with nine state agencies. The data stores are disparate and heterogeneous and range from small Microsoft Access datasets to data stored in mainframe legacy systems both within and outside the health department information system enterprise.…”

Section: Discussionmentioning

confidence: 99%

A case for using grid architecture for state public health informatics: the Utah perspective

Staes

LeFevre

et al. 2009

BMC Med Inform Decis Mak

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This paper presents the rationale for designing and implementing the next-generation of public health information systems using grid computing concepts and tools. Our attempt is to evaluate all grid types including data grids for sharing information and computational grids for accessing computational resources on demand. Public health is a broad domain that requires coordinated uses of disparate and heterogeneous information systems. System interoperability in public health is limited. The next-generation public health information systems must overcome barriers to integration and interoperability, leverage advances in information technology, address emerging requirements, and meet the needs of all stakeholders. Grid-based architecture provides one potential technical solution that deserves serious consideration. Within this context, we describe three discrete public health information system problems and the process by which the Utah Department of Health (UDOH) and the Department of Biomedical Informatics at the University of Utah in the United States has approached the exploration for eventual deployment of a Utah Public Health Informatics Grid. These three problems are: i) integration of internal and external data sources with analytic tools and computational resources; ii) provide external stakeholders with access to public health data and services; and, iii) access, integrate, and analyze internal data for the timely monitoring of population health status and health services. After one year of experience, we have successfully implemented federated queries across disparate administrative domains, and have identified challenges and potential solutions concerning the selection of candidate analytic grid services, data sharing concerns, security models, and strategies for reducing expertise required at a public health agency to implement a public health grid.

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Proton deshielding by spatial proximity: An experimental and theoretical study for ortho‐substituted anisoles

Contreras

Ferraro

Kowalewski

et al. 1985

Magnetic Reson in Chemistry

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A quantitative estimation of the proton deshielding effect produced by a steridy crowded environment was obtained experimentally, based on departures from the chemical shift additivity rule of protons ortho to OCH, and NOz groups in benzene derivatives, where a conformational change from these side-chain groups is expected. The intluences of these conformational changes were also analysed from a theoretical point of view. Calculations of the magnetic shielding tensor were carried out at the INDO approximation with gauge invariant atomic orbitals, together with the uncoupled Hartree-Fock approach. Theoretical results for these proton deshielding effects are in very good agreement with those determined experimentally.

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The use of partially restricted molecular orbitals to investigate transmission mechanisms of spin–spin coupling constants. III—an INDO study of long‐range FH couplings in fluorinated derivatives of toluene

Cited by 20 publications

References 21 publications

The carbonyl group as a reluctant transmitter of hyperconjugative or σ–π spin–spin coupling interactions in derivatives of benzaldehyde, acetophenone, and benzophenone

The carbonyl group as a reluctant transmitter of hyperconjugative or σ–π spin–spin coupling interactions in derivatives of benzaldehyde, acetophenone, and benzophenone

A case for using grid architecture for state public health informatics: the Utah perspective

Proton deshielding by spatial proximity: An experimental and theoretical study for ortho‐substituted anisoles

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