John Dugdale, Michael Prescott, Mark Stretton, Barney Spender, Barbara Hall, Aa Gill, Helen Kirwan-Taylor, Jean Brett Chair, Jim Munro, Jon Swain, James Clark, Nicholas Rufford, Kenny Farquharson, Rob Hughes, John Peter, Arthur Hayward-Costa, Andy Gould, David Watkins, Amanda Ursell, Jonathan Miller, Emma Moore, Brenda Kemp, Dr Stanley Ho, Beth Christie, Jane Mulkerrins, J D, Mark Souster, Tim Nagle, Gareth Walsh, Frank Whitford, Ivo Tennant, Ferdinand Mount, Kathryn Cooper, David Smith, Melanie Phillips, Nick Pitt, Neil Wormald, Andrew Sullivan, Michael Thrasher, Clive Davis, Stephen Grey, Lynne Truss, Dr Roger Henderson, Ronald Stewart-Brown, Martin James, Simon Wilde, Peter Nichol, William Hague, Tom Walker, Phil Smith, Anthony Sattin, Robert Winnett, Anglia, Irwin Stelzer, Jane Moore, Tom English, Robert Hewison, H Gallows, Mark Richardson, David Dougill, Katie Potter, John Evans, Charles Shoebridge, Germaine Greer writer, Terry Jenkins, Sarah Toyne, David Hewson, Jeremy Wilson, Frank Oldfield, Jonathon Carr-Brown, Alasdair Reid, Margarette Driscoll, Steve Baron, John Richmond, Jeremy Clarkson, Derek Budd, Stewart Lee, Peter Conradi, Philip Hobsbaum, Louise Taylor, Peter Kemp, Max Anderson, James Inglis, Jane Renton, Cheryl Markosky, Eben Black, Robert Harris, Nicholas Bennett Chief Executive, John O'Donnell, Anita Chaudhuri, K Phillips, Nicholas Pine, Josie Lawrence, S W, Nick Gardner, Richard Lyddon, Brendan Bourne, Peter Parker, Mike Laws, Richard Johnson, Paul Ham, Stuart Wavell, Roger Eglin, Stella Bingham, Michael Jeffels, Jilly Cooper, Hugh McIlvanney, Stewart Anderson, Joanna Koenig, James Clark Home Affairs Correspondent, Lucinda Kemeny, Jasper Gerard, Paul Driver, Garth Pearce, John Humphrys, Patrick Garratt, Peter Windsor, Nicholas Hellen, Richard Brooks, John Follain, Ian Hawkey, Alastair Rowlett, Shelley Von Strunckel, Stuart Andrews, Amber Cowan, Paul Durman, Neil Mackwood, Mark Edwards, Kirstie Hamilton, Susan Clark, Danny O'Brien, Dugald Barr, David Carter, Hugh Canning, Claudia, Richard Holmes, Sean Newsom, Raymond Keene, Gareth Huw Davies, Nigel Benn, Stanley Stewart, Leah Brookes, Cosmo Landesman, Robbie Hudson, George Manning, Diana Wright, Andy Knott, Simon James, Chris Partridge, John Moore, Richard Evans, Uzi Mahnaimi, Nick Cain, Peta Bee, Father John Buckley Our Lady Queen of Apostles Catholic Church, Natalie Graham, Dominic Rushe, Nick Rennison, Ted Heath, David Walsh, Peter Perceval, David Lodge, Alex Kadis, John Stern, David Cornish, S Rooney, Bryan Appleyard, Lois Rogers Medical Correspondent, Stephen Armstrong, John Elliott, Martin Venables, Madsen Pirie, David Selbourne, Richard Woods, Roland White, Garth Alexander, Jo Anne Nadler, Joseph Sinclair, Maurice Chittenden, Richard Rae, Mark Franchetti, Ray Hutton, Frank Fitzgibbon, Jon Ungoed-Thomas, Martin Ivens, David, Susan Elkin, John Crossland, Michael Sheridan, D J Taylor, John Harlow, Godfrey Smith, Julie Burchill writer, John Urbanek, Dipesh Gadher, Barry Collins, John Waples, A A Gill, Christopher Reed, Matthew Campbell, Brian Glanville, N W, Tom Robbins, Nick Fielding, Stephen Pettitt, Claudia Croft, R H, Jackie Rowley, Sally Kinnes, Alan English, Sally Andrew, Naomi Caine, Nicholas Hellen Media Editor, Thrasy Petorpoulos, David Wickers, Roger Dobson, Tom Rhodes, Helena Christensen, Tony Probert, Keith Dunnett, Graham Hopkins, Richard White, Mark Hodson, Graham Norwood, Joe Lovejoy, Jonathan Futrell, Colin Rallings, Rupert Steiner, Hugh Pearman, Katie Ebben, Dan Cairns, Simon Sebag Montefiore, Baz Luhrmann, David Parsley, David Grylls, David Smith Economics Editor, Neil MacLean, Richard Peel, Simon Wardell, Joanna Simon, India Knight, Victoria Stanley, Steve Grant, Kingston Smith, John Sawtell, Simon Howard, Dan Pearson, Rosie Waterhouse, Boris Schapiro, Karen Robinson,
... Mia! Wigmore Hall Barbican Royal Festival Hall Mikhail Rudy The Entertainer Multiple Classified Advertising Items The triumph ...
2001 - Gale Group | Sunday Times HA GDA
Reino Laatikainen, J. Ratilainen, Rudy Sebastian, Harri Santa,
... Aromatics in Strong Magnetic FieldReino Laatikainen, Jari Ratilainen, Rudy Sebastian, and Harri SantaCite this: J. Am. Chem. Soc. ...
Tópico(s): NMR spectroscopy and applications
1995 - American Chemical Society | Journal of the American Chemical Society
Selwyn Hodson Pressinger, John Dugdale, Sebastian Hamilton Westminster Correspondent, Roy Ward, Christopher Middleton, Saffron Aldrige, Barbara Hall, Judith O'Reilly Education Correspondent, Michael Ashworth, Andrew Grlce, Tam Dalyell Mp, John Crawley, Jim Munro, Jon Swain, Greg Williams, Nicholas Rufford, John Peter, David Clementi's, Walter F Stowy, Emma Moore, Amanda Ursell, Jonathan Miller, Lesley White, John Jay, Dr Charles, Eamonn Allen, Claire Struthers, Raymond Franks, A Vest, Ivo Tennant, William Wilson, Sandra Hawke, B W, Alistair Scott, Addison de Witt, Hazel Courteney Health Journalist of the Year, J P, Paul Myatt, Lucy Hughes-Hallett, Kirstie Hamilton City Editor, Neil Wormald, Andrew Sullivan, Pearl Abraham, Mary Wilson, Aoife O'Brien, Mrs M Wrigg, Andrew Grice Political Editor, Jeffrey Archer, Richard Slobodin, Tony Allen-Mills, Isabella Blow, Martin James, Anthony Sattin, Robert Winnett, Irwin Stelzer, Robert Hewison, Peter Wilson, Roger Anderson, Marian Phillips, David Dougill, Matthew Marr, Robert Johnson, Donald Artrim, Peter Jones, David Hewson, E Smith, Tom Cruise, Tania Alexander, Harvey Porlock, Yvonne Ridley, Margaret Coles, Margarette Driscoll, Alasdair Reid, Debble Hill, Hugh Canning, Jeremy Clarkson, ken Russell, Edward Porter, Peter Conradi, Jerry Lloyd, Louise Taylor, Mrs J Sutton, Michael Jones, Peter Millar, David Dabydeen, Duncan Keegan, Dr Michael Sanderson, Peter Hadfield, Joan Smith, George Perry, Kevin Connolly, Graham Otway, John Primeau, Nick Gardner, Shelley von Strunckel, Jeremy Taylor, Paul Nuki Consumer Affairs Correspondent, Rob Steen, Geoffrey Dicks, Alexander Korzhakov, Naoml Calne, Jon Freeman, Paul Ham, Ian MacKinnon, Dennis L Bird, Michael Travis, Guy Richards, Jack Millan, Jonathan Leake Transport Correspondent, Elizabeth Gaskell, Paul Donovan, Ron Brown, Christopher trussler, Eric Lyman, Jeff Randall, Smita Talati, Paul Driver, Cosmo landesman, Mwanyengela Ngali, Ian Hawkey, Ian Chadband, David Leppard, Richard Girling, Kirstie Hamilton, Tom Shone, Stephen Amidon, Mark Austin, David Lawrenson, Nicholas Rufford Home Affairs Editor, Justin Onyeka, Naomi Calne, Lord Simon, Andy Goldberg, David Hurst, Helen Fielding, Christina Lamb, Katharine Klein, Anna Pasternak, Sean Newsom, Bob Graham, Sue Reid, Raymond Keene, Brian Masters, Anne Tyler, Peter Gordon, Zoe Brennan, Andrew Roberts, Marie Colvin, Diana Wright, Helen Hawkins, Rebecca Tanqueray, Frank Kane, Uzi Mahnaimi, Michael Wright, Andrew Smith, Paul Nuki, Tim Moorey, Andrew Grice, Steve Connor Science Correspondent, Martin Searby, Adam Pearsons, Keith Wheatley, David Walsh, Henry Roth, Rasselas, Bryan Appleyard, Stephen McGinty, Ann Swinfen, Valerie Sleith, Mr J Riddings, Josh Salzmann, Mark Prigg, Garth Alexander, Rachel Cooke, Maurice Chittenden, Alex Fortune, Andrew Lorenz Business Editor, Mark Franchetti, Graham Gooch, Ray Hutton, John burnside, Susan Elkin, Jonathan Leake, Catharine Straker, Leah Hardy, Sean Hargrave, Margaret Walters, Bruce Anderson, John Harlow, Simon Callow, Matthew Lynn, Kofi Allen, Quentin Blake, D L, John Waples, Rupert Stelner, A A Gill, Paul Barker, Lord Brocket, Richard E Grant, Ernest Smith, David Hutcheon, Rajeev Syal, Nadine Meisner, Caroline Law, Lauren St John, Stephen Pettitt, Howard Jacobson, Cherry Norton, John Spurling, Roger Brandon, Andrew Lorenz, David Foster, Liam Clarke, David Wickers, Roger Dobson, Lord Wakeham, Tim Roth, Matthew Loup, Arthur Miller, Mark Hodson, Francesco Sisci, Nicholas Hellen Media Correspondent, Steve Connor, Joe Lovejoy, Neil Chapman, Charles Kingsley, Rupert Steiner, Seamus Deane, Chris Lightbown, Alberto Manguel, R Brian, Frank Whiteford, Philip Berry, Derek Draper, Simon Trump, Harry Thompson, Anthony Howard, Simon Sebag, Judith O'Relly Education Correspondent, Claire Middleton, Zoe Linkson, Polly Walshe, Joanna Simon, India Knight, Maureen Keywood, Mandy Piggot, Dan Pearson, William Essex, Stephen Hayward, Boris Schapiro, Adam Parsons,
... breaks, not even a chancellor can do anything ' Rudy vs Ruth, last New York liberal Peruvian president ...
1997 - Gale Group | Sunday Times HA GDA
D. I. Hoult, John K. Saunders, Garnette R. Sutherland, Jonathan C. Sharp, Marcia Gervin, H. Glen Kolansky, D. Kripiakevich, Andrew E. Procca, Rudy Sebastian, Akos Dombay, David L. Rayner, Frank A. Roberts, Bogusław Tomanek,
The engineering of a novel intra-operative MRI system is described. A movable, 1.5 Tesla MRI magnet was placed in a neurosurgical operating room without affecting established neurosurgical procedure. The system allows fast, high-quality MR intra-operative imaging of the brain and spine without the necessity of patient transportation. A neuro-navigational device capable of displaying and updating spatially referenced MR images in the operating room was integrated with the MRI system. Over 100 procedures ...
Tópico(s): Medical Image Segmentation Techniques
2001 - Wiley | Journal of Magnetic Resonance Imaging
Jonathan C. Sharp, John Copps, Q. Liu, Lawrence Ryner, Rudy Sebastian, George Q. Zeng, Steven R. Smith, Julie O. Niere, Bogusław Tomanek, Masahiko Sato,
Resistance of bone to fracture--bone strength--has been shown to depend on both the amount of bone and its architectural spatial organization. In vivo magnetic resonance (MR) techniques have the capability of imaging bone tissue, including the trabecular microarchitecture and the marrow composition. We have applied in vivo and ex vivo MR methods to the tibia in an ovariectomized rat model of osteoporosis. Specifically, in vivo high-resolution three-dimensional MR imaging and localized MRS were facilitated ...
Tópico(s): Bone and Joint Diseases
2000 - Oxford University Press | Journal of Bone and Mineral Research
Ted Schaefer, Robert W. Schurko, Rudy Sebastian, Frank E. Hruska,
The 1 H, 19 F, and 13 C {H} nuclear magnetic resonance spectra at 300 K of 4-fluoro- and 3,5-difluorobenzyl fluoride, dissolved in CS 2 –C 6 D 12 and acetone-d 6 , are fully analyzed. Spin–spin coupling constants over four, five, and six formal bonds are used to derive expectation values of sin 2 θ and [Formula: see text] and the apparent twofold internal rotational potentials; [Formula: see text] is the angle by which the α C—F(C—H) bond twists out of the ring plane. The conformation of lowest energy ...
Tópico(s): Molecular spectroscopy and chirality
1995 - NRC Research Press | Canadian Journal of Chemistry
Ted Schaefer, Rudy Sebastian, David M. McKinnon, Perry W. Spevack, Kerry J. Cox, Craig S. Takeuchi,
Precise 1 H nuclear magnetic resonance spectral parameters are reported for salicyladehyde and its 3-fluoro and 5-fluoro derivatives in nonpolar solutions. Such data are also given for the 2-mercapto, 2-methylthio, and 2-methoxy derivatives of benzaldehyde. Comparison of the long-range coupling constants in the various compounds and their conformers shows a large perturbation of their magnitudes by hydrogen bond formation. For the salicylaldehyde system, the perturbation is particularly large for ...
Tópico(s): Analytical Chemistry and Chromatography
1993 - NRC Research Press | Canadian Journal of Chemistry
Geometry-optimized STO-3G and 6-31G MO computations are presented for the internal rotational potentials in the monofluorostyrenes. These are compared with experimental values, particularly those from fluorescence experiments with a supersonic jet.
Tópico(s): Atmospheric Ozone and Climate
1989 - Elsevier BV | Chemical Physics Letters
Molecular orbital computations with the basis set 6-31G are reported for seven values of θ, the torsion angle about the [Formula: see text] bond in anisole. All bond angles and lengths are optimized but the atoms of the phenyl group are constrained to a plane. The relative energies are fit by V(θ)/kJ mol −1 = 7.78(5) sin 2θ + 2.41(5) sin 2 2θ − 0.54(5) sin 2 3θ, where θ is zero when the heavy-atom skeleton is planar. Computations with the basis set 6-31G*(5D) for three values of θ can be reproduced by V( ...
Tópico(s): Various Chemistry Research Topics
1989 - NRC Research Press | Canadian Journal of Chemistry
Ted Schaefer, Rudy Sebastian, Glenn H. Penner,
Geometry-optimized STO-3G MO computations of the internal rotational potential about the [Formula: see text] bond in isopropylbenzene yield V (kJ/mol) as 14.1(3) sin 2 ψ − 2.8(3) sin 2 2ψ + 1.4(3) sin 2 3ψ; ψ is the angle by which the α C—H bond deviates from the benzene plane. This result provides no support for the very low internal barrier once hypothesized from microwave data for isopropylbenzene in the vapor phase, nor for the local minimum at ψ = 90° inferred from hyperfine coupling constants in π ...
Tópico(s): Photochemistry and Electron Transfer Studies
1988 - NRC Research Press | Canadian Journal of Chemistry
Frank E. Hruska, Rudy Sebastian, André Grand, L. Voituriez, Jean Cadet,
X-ray crystallography was used to determine the structure of (−)cis(5R,6S)-5,6-dihydroxy-5,6-dihydrothymidine, a γ-radiation induced product of thymidine. The crystals belong to the orthorhombic space group P2 1 2 1 2 1 and have cell dimensions a = 8.420(1) Å, b = 10.422(1) Å, and 13.552(1) Å. The half-chair pucker of the 5,6-saturated pyrimidine ring is similar to that observed for the isolated base with the cis configuration, and is described by the Cremer–Pople parameters Q = 0.48 Å, θ = 62°, and [Formula: ...
Tópico(s): DNA and Nucleic Acid Chemistry
1987 - NRC Research Press | Canadian Journal of Chemistry
Ted Schaefer, Glenn H. Penner, Rudy Sebastian,
Rather extensive geometry-optimized computations at the STO-3G, 4-21G, 4-31G, and 6-31G levels of abinitio molecular orbital theory suggest that the fourfold component of the barrier to internal rotation about the C sp 2 —C sp 3 bond in ethylbenzene amounts to about 20% of the twofold component. The 1 H nuclear magnetic resonance spectral parameters, extracted by complete analyses of the spectra arising from the ten protons, are reported for ethylbenzene in acetone-d 6 , CCl 4 , CS 2 , and perfluoromethylcyclohexane ...
Tópico(s): Molecular Spectroscopy and Structure
1987 - NRC Research Press | Canadian Journal of Chemistry
Glenn H. Penner, Ted Schaefer, Rudy Sebastian, Saul Wolfe,
The apparent twofold barriers to rotation about the exocyclic C—C bonds in ArCH 2 X (X = SH, SMe, S(O)Me, SO 2 Me) compounds have been determined in CS 2 and in benzene-d 6 , from the magnitudes of long-range proton–proton coupling constants. The work extends earlier studies of the systems X = F, Cl. Except for X = F, all of the title compounds have a low energy conformation in which the C—X bond is perpendicular to the plane of the benzene ring. The introduction of two meta-chlorine substituents leads to ...
Tópico(s): Solid-state spectroscopy and crystallography
1987 - NRC Research Press | Canadian Journal of Chemistry
Ted Schaefer, Rudy Sebastian, Reino Laatikainen, Salman R. Salman,
1 H nmr spectral parameters are reported for salicylaldehyde and 15 of its derivatives in dilute CCl 4 solutions. In those compounds in which sufficiently large substituents are placed ortho to either of the functional groups or in which substituents enhance the charge density in the carbonyl group, a positive spin–spin coupling is observed between the two sidechain protons. This coupling, formally over five bonds, correlates with the chemical shift of the hydroxyl proton. The coupling mechanism ...
Tópico(s): Photochemistry and Electron Transfer Studies
1984 - NRC Research Press | Canadian Journal of Chemistry
Ted Schaefer, Timothy A. Wildman, Rudy Sebastian,
Tópico(s): Molecular spectroscopy and chirality
1982 - Elsevier BV | Journal of Molecular Structure THEOCHEM
Ted Schaefer, Rudy Sebastian, James Peeling, Glenn H. Penner, Kevin Siong-Ve Koh,
STO-3G MO computations, with substantial geometry optimization, are reported for benzyl alcohol. They are performed at 15° intervals for the angle by which the C—O bond twists out of the plane of the phenyl group, as well as for 30° intervals for the HCOH dihedral angle. The ensuing conformational energies are used to estimate expectation values of these two angles as well as of functions of these angles. The latter are compared with those obtained from long-range proton–proton coupling constants ...
Tópico(s): Various Chemistry Research Topics
1989 - NRC Research Press | Canadian Journal of Chemistry
Geometry-optimized STO-3G and 4-31G molecular orbital computations yield 8.6 and 7.8 kJ mol−1, respectively, for the inversion barrier in 9,10-dihydroanthracene. The folding angle in the boat form of the molecule is computed as 140.7 and 141.°3, respectively, to be compared with a value of 144.°7 in the crystal. The computed internal bond angles and carbon-carbon bond lengths agree rather well with the X-ray structure.
Tópico(s): Advanced Chemical Physics Studies
1987 - Elsevier BV | Journal of Molecular Structure THEOCHEM
Geometry-optimized STO-3G MO computations at various folding angles are reported for dibenzo-p-dioxin, for which some ambiguity exists concerning its puckering behaviour. The planar molecule is computed to be most stable, but compared to thermal energies the potential is very flat near the minimum. At 300 K the average folding angle is calculated as 168.3°. The theoretical puckering potential appears to be consistent with the available experimental data for solutions of dibenzo-p-dioxin and possibly ...
Tópico(s): Toxic Organic Pollutants Impact
1990 - Elsevier BV | Journal of Molecular Structure THEOCHEM
Tópico(s): Molecular Spectroscopy and Structure
1987 - Elsevier BV | Journal of Magnetic Resonance (1969)
Ted Schaefer, Rudy Sebastian, Glenn H. Penner,
A precise analysis of the 1 H nmr spectrum of toluene as a dilute solution in carbon disulfide yields a revised set of spectral parameters. The chemical shift of the para proton lies 12.6 ppb to low frequency of that of the ortho protons at 300 K. The ring proton chemical shifts are discussed and compared with 1 H and 3 H shifts observed in carbon tetrachloride. The long-range couplings between methyl and ring protons can be said to be quantitatively understood in terms of σ and σ–π electron transmitted ...
Tópico(s): Analytical Chemistry and Chromatography
1985 - NRC Research Press | Canadian Journal of Chemistry
Ted Schaefer, Glenn H. Penner, Rudy Sebastian, James Peeling, Christian Beaulieu,
Internal rotational potentials for rotation about the Csp 2 —O bond in C 6 H 5 OCF 3 and its 4-fluoro derivative are computed at the STO-3G and 3-12G levels of molecular orbital theory. As for anisole, the perpendicular conformer is calculated as least stable for C 6 H 5 OCF 3 but the height of the internal barrier is considerably lower than in anisole. The 4-fluoro substituent reduces the twofold component significantly, indicating reduced p …π conjugation, but does not much change the values of ...
Tópico(s): Molecular spectroscopy and chirality
1991 - NRC Research Press | Canadian Journal of Chemistry
Ted Schaefer, Christian Beaulieu, Rudy Sebastian, Glenn H. Penner,
The twofold barrier to rotation about the [Formula: see text] bond in benzyl fluoride is deduced from the long-range 1 H, 1 H; 1 H, 19 F; and 13 C, 19 F nuclear spin–spin coupling constants in solution. The barrier changes from 3.2(2) kJ/mol in the polar solvent, acetonitrile-d 3 , to 0.7(2) kJ/mol in the nonpolar environment provided by cyclohexane-d 12 . In all solutions the conformer of greatest stability has the C—F bond in a plane perpendicular to that of the phenyl group. Extrapolation of the barrier ...
Tópico(s): Advanced Physical and Chemical Molecular Interactions
1990 - NRC Research Press | Canadian Journal of Chemistry
Ted Schaefer, Rudy Sebastian, Timothy A. Wildman,
The 1 H nmr spectra of 2-allylphenol, 2-allyl-6-methylphenol, 2-allyl-6-chlorophenol, and 2-benzyl-4-chlorophenol are analyzed in some detail. It is shown that, relative to a methyl group, the allyl and benzyl moieties, respectively, favor a cis orientation by 1570 ± 250 J/mol and 900 ± 220 J/mol in free energy at 305 K in CCl 4 solution. These numbers appear to be independent of the CCl 4 solvent. Coupling parameters within the allyl group in these molecules and in propene and allylbenzene show some ...
Tópico(s): Free Radicals and Antioxidants
1979 - NRC Research Press | Canadian Journal of Chemistry
Ted Schaefer, Wing Keung Chan, Rudy Sebastian, Robert W. Schurko, Frank E. Hruska,
The 1 H nuclear magnetic resonance spectra of ethylbenzene-β- 13 C in CS 2 /C 6 D 12 and acetone-d 6 solutions yield long-range 1 H, 1 H and 1 H, 13 C coupling constants. The 13 C { 1 H} NMR spectra yield 13 C, 13 C couplings. The conformational dependence of some of these coupling constants is compatible with two values of the barrier to internal rotation about the exocyclic Csp 2 —Csp 3 bond. If the fourfold component of the internal rotational potential is not larger than about 20% of the twofold ...
Tópico(s): Analytical Chemistry and Chromatography
1994 - NRC Research Press | Canadian Journal of Chemistry
Ted Schaefer, Rudy Sebastian, Frank E. Hruska,
Some molecular orbital calculations on the title molecules imply that correlation-gradient computations will be necessary if the internal barriers are to agree with those deduced from torsional frequencies. For example, the energy difference between the planar and perpendicular conformers of benzaldehyde is 34.7 kJ mol−1 for an MP2/6-311G∗//6-31G∗(5D) computation. A calculation of the difference of the zero point energies of the two conformers, using somewhat less flexible basis sets, suggests that ...
Tópico(s): Molecular spectroscopy and chirality
1993 - Elsevier BV | Journal of Molecular Structure THEOCHEM
Ted Schaefer, Rudy Sebastian, Glenn H. Penner,
The 1 H nuclear magnetic resonance spectra of benzyl silane and benzyl trichlorosilane, obtained in CS 2 and benzene-d 6 solutions, are analyzed. The long-range coupling constants between the methylene and para ring protons are used to derive apparent twofold barriers about the Csp 2 —Csp 3 bonds of 7.4 ± 1.6 and 8.1 ± 1.1 kJ/mol for the silane and the trichlorosilane, respectively. These are higher than that for ethylbenzene and are attributed mainly to the stabilization of the perpendicular conformer, ...
Tópico(s): Molecular spectroscopy and chirality
1991 - NRC Research Press | Canadian Journal of Chemistry
The parameters for the high resolution 1 H and 19 F NMR spectra of 2-, 3-, and 4-fluorostyrene are reported for solutions in CS 2 and acetone-d 6 at 300 K. The populations of the planar cis and trans conformers of 2- and 3-fluorostyrene are deduced from the long-range coupling constants involving the meta and α protons. These populations are insensitive to solvent and appear to be in reasonable agreement with previous 6-31G MO computations for the free molecule; they are also compared with populations ...
Tópico(s): Analytical Chemistry and Chromatography
1990 - NRC Research Press | Canadian Journal of Chemistry
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTChlorine-37/chlorine-35 isotope effects on the proton NMR spectra of some chloromethane derivatives. Practical consequencesTed Schaefer and Rudy SebastianCite this: J. Am. Chem. Soc. 1987, 109, 21, 6508–6509Publication Date (Print):October 1, 1987Publication History Published online1 May 2002Published inissue 1 October 1987https://pubs.acs.org/doi/10.1021/ja00255a044https://doi.org/10.1021/ja00255a044research-articleACS PublicationsRequest reuse permissionsArticle ...
Tópico(s): Molecular spectroscopy and chirality
1987 - American Chemical Society | Journal of the American Chemical Society
Ted Schaefer, Timothy A. Wildman, Rudy Sebastian,
It is suggested that the five-bond spin–spin coupling constant between the sulfhydryl proton and the ring proton in the meta position is given by [Formula: see text]. Here θ is the angle by which the S—H bond twists out of the benzene plane and angular brackets indicate expectation or average values, determined by the twofold barrier to internal rotation about the C—S bond. [Formula: see text] is the π electron contribution and has a maximum at θ = 90° and [Formula: see text] is the σ electron contribution ...
Tópico(s): Spectroscopy and Quantum Chemical Studies
1982 - NRC Research Press | Canadian Journal of Chemistry
Ted Schaefer, Rudy Sebastian, Salman R. Salman, James Baleja, Glenn H. Penner, David M. McKinnon,
The proximate coupling constants, 5 J, between ortho and methyl protons in thioanisole and 18 of its derivatives are discussed as conformational indicators. On the assumption that 5 J varies as cos 4 θ, for 0° ≤ θ ≤ 90°, θ being the angle by which the methyl group twists out of the aromatic plane, 5 J for θ = 0° follows as −0.43 (2) Hz from the known internal barrier in thioanisole in solution. A measurement of 5 J in meta- or para-substituted thioanisole derivatives then yields an approximate value for ...
Tópico(s): Chemical Reaction Mechanisms
1991 - NRC Research Press | Canadian Journal of Chemistry