Determination ofJCCCoupling Constants Using Parahydrogen-Induced Polarization

Natterer, Johannes; Barkemeyer, Jens; Bargon, Joachim

doi:10.1006/jmra.1996.0247

Cited by 12 publications

(4 citation statements)

References 4 publications

(7 reference statements)

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“…It turns out that ν 2 and ν 3 are not independent but can be gathered into a single normalized mode ν‘, also orthogonal to ν 1 : with the benefit that eqs 3 reduces to two simultaneous first-order differential equations While the initial value of mode ν 1 is −√2 , we shall denote by K the initial value of mode ν‘ ( K should be very large and is associated with the initial polarization). As clearly demonstrated in several recent NMR works − and as p-H 2 corresponds to a singlet state, this can arise solely from a nonzero (initial) value for the longitudinal spin order (2 ) involved mode ν‘. It turns out that if only p-H 2 is considered, the initial state is represented by I A I A‘ and ν‘(0) would be zero.…”

Section: Theorymentioning

confidence: 78%

Longitudinal Nuclear Relaxation in an A₂Spin System Initially Polarized through Para-Hydrogen

Aime¹,

Gobetto

Canet

1998

J. Am. Chem. Soc.

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Os 3 (CO) 10 (NCCH 3 ) 2 has been hydrogenated with para-hydrogen to yield H 2 Os 3 (CO) 10 where the two hydrogen nuclei remain magnetically equivalent and therefore in a singlet state. Despite this equivalence, an enhanced longitudinal magnetization is observed to decrease toward thermal equilibrium. It is postulated that this enhanced magnetization is created through a nuclear relaxation interference mechanism (cross-correlation between dipolar interaction and chemical shift anisotropy); decay curves are then successfully analyzed by means of a spin relaxation theory adapted to this situation.

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Section: Theorymentioning

confidence: 78%

Longitudinal Nuclear Relaxation in an A₂Spin System Initially Polarized through Para-Hydrogen

Aime¹,

Gobetto

Canet

1998

J. Am. Chem. Soc.

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“…Some others feature a p/4 r.f. read pulse at the end of the pulse sequence [33,[38][39][40][41][42][43].…”

Section: Building Blockmentioning

confidence: 99%

Selective detection of hyperpolarized NMR signals derived from para-hydrogen using the Only Para-hydrogen SpectroscopY (OPSY) approach

Aguilar

Adams

Duckett

et al. 2011

Journal of Magnetic Resonance

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“…Furthermore, because the occurrence of 13 C- 13 C groupings is 100 times lower than the basic 13 C level, experiments designed to monitor this arrangement are extremely insensitive and typically take many hours to complete. Natterer et al 10 have completed this sort of measurement with p-H 2 in minutes when examining alkyne hydrogenation products. Parahydrogen induced polarisation has also been used in conjunction with 2-D methods such as heteronuclear multiple quantum coherence spectroscopy (HMQC), to facilitate rapid indirect observation of insensitive nuclei such as 103 Rh and 195 Pt from sub-milligram samples.…”

Section: Introductionmentioning

confidence: 99%

Activation of H2 by halogenocarbonylbis(phosphine)rhodium(I) complexes. The use of parahydrogen induced polarisation to detect species present at low concentration

Morran¹,

Duckett²,

Howe³

et al. 1999

J. Chem. Soc., Dalton Trans.

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Complexes of the form RhX(CO)(PR 3 ) 2 [X = Cl, Br or I; R = Me or Ph] reacted with H 2 to form a series of binuclear complexes of the type (PR 3 ) 2 H 2 Rh(µ-X) 2 Rh(CO)(PR 3 ) [X = Cl, Br or I, R = Ph; X = I, R = Me] and (PMe 3 ) 2 (X)-HRh(µ-H)(µ-X)Rh(CO)(PMe 3 ) [X = Cl, Br or I] according to parahydrogen sensitised 1 H, 13 C, 31 P and 103 Rh NMR spectroscopy. Analogous complexes containing mixed halide bridges (PPhare detected when RhX(CO)(PPh 3 ) 2 and RhY(CO)(PPh 3 ) 2 are warmed together with p-H 2 . In these reactions only one isomer of the products (PPh 3 ) 2 H 2 Rh(µ-I)(µ-Cl)Rh(CO)(PPh 3 ) and (PPh 3 ) 2 H 2 Rh(µ-I)-(µ-Br)Rh(CO)(PPh 3 ) is formed in which the µ-iodide is trans to the CO ligand of the rhodium() centre. When (PPh 3 ) 2 H 2 Rh(µ-Cl)(µ-Br)Rh(CO)(PPh 3 ) is produced in the same way two isomers are observed. The mechanism of the hydrogen addition reaction is complex and involves initial formation of RhH 2 X(CO)(PR 3 ) 2 [R = Ph or Me], followed by CO loss to yield RhH 2 X(PR 3 ) 2 . This intermediate is then attacked by the halide of a precursor complex to form a binuclear species which yields the final product after PR 3 loss. The (PPh 3 ) 2 H 2 Rh(µ-X) 2 Rh(CO)(PPh 3 ) systems are shown to undergo hydride self exchange by exchange spectroscopy with rates of 13.7 s Ϫ1 for the (µ-Cl) 2 complex and 2.5 s Ϫ1 for the (µ-I) 2 complex at 313 K. Activation parameters indicate that ordering dominates up to the rate determining step; for the (µ-Cl) 2 system ∆H ‡ = 52 ± 9 kJ mol Ϫ1 and ∆S ‡ = Ϫ61 ± 27 J K Ϫ1 mol Ϫ1 . This process most likely proceeds via halide bridge opening at the rhodium() centre, rotation of the rhodium() fragment around the remaining halide bond and bridge re-establishment. If the triphenylphosphine ligands are replaced by trimethylphosphine distinctly different reactivity is observed. When RhX(CO)(PMe 3 ) 2 [X = Cl or Br] is warmed with p-H 2 the complex (PMe 3 ) 2 (X)HRh(µ-H)(µ-X)Rh(CO)(PMe 3 ) [X = Cl or Br] is detected which contains a bridging hydride trans to the rhodium() PMe 3 ligand. However, when X = I, the situation is far more complex, with (PMe 3 ) 2 H 2 Rh(µ-I) 2 Rh(CO)(PMe 3 ) observed preferentially at low temperatures and (PMe 3 ) 2 (I)HRh(µ-H)-(µ-I)Rh(CO)(PMe 3 ) at higher temperatures. Additional binuclear products corresponding to a second isomer of (PMe 3 ) 2 (I)HRh(µ-H)(µ-I)Rh(CO)(PMe 3 ), in which the bridging hydride is trans to the rhodium() CO ligand, and (PMe 3 ) 2 HRh(µ-H)(µ-I) 2 Rh(CO)(PMe 3 ) are also observed in this reaction. The relative stabilities of related systems containing the phosphine PH 3 have been calculated using approximate density functional theory. In each case, the (µ-X) 2 complex is found to be the most stable, followed by the (µ-H)(µ-X) species with hydride trans to PH 3 .

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Determination ofJCCCoupling Constants Using Parahydrogen-Induced Polarization

Cited by 12 publications

References 4 publications

Longitudinal Nuclear Relaxation in an A₂Spin System Initially Polarized through Para-Hydrogen

Longitudinal Nuclear Relaxation in an A₂Spin System Initially Polarized through Para-Hydrogen

Selective detection of hyperpolarized NMR signals derived from para-hydrogen using the Only Para-hydrogen SpectroscopY (OPSY) approach

Activation of H2 by halogenocarbonylbis(phosphine)rhodium(I) complexes. The use of parahydrogen induced polarisation to detect species present at low concentration

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Determination ofJCCCoupling Constants Using Parahydrogen-Induced Polarization

Cited by 12 publications

References 4 publications

Longitudinal Nuclear Relaxation in an A2Spin System Initially Polarized through Para-Hydrogen

Longitudinal Nuclear Relaxation in an A2Spin System Initially Polarized through Para-Hydrogen

Selective detection of hyperpolarized NMR signals derived from para-hydrogen using the Only Para-hydrogen SpectroscopY (OPSY) approach

Activation of H2 by halogenocarbonylbis(phosphine)rhodium(I) complexes. The use of parahydrogen induced polarisation to detect species present at low concentration

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Longitudinal Nuclear Relaxation in an A₂Spin System Initially Polarized through Para-Hydrogen

Longitudinal Nuclear Relaxation in an A₂Spin System Initially Polarized through Para-Hydrogen