Transition metal NMR spectroscopy. Part XXIII. Rhodium-103 shielding and the stereoselectivity of dihydrogen (H2) addition to diastereomeric olefin complexes

Bender, Bruce R.; Koller, Markus; Nanz, Daniel; Philipsborn, W. Von

doi:10.1021/ja00066a093

Cited by 54 publications

(41 citation statements)

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“…33 The numbers are in agreement with estimates based on the Knight shift for metallic rhodium. 34,40 Concerning the issue of spectral reference, it is noted that, traditionally, a number of compounds have been used as reference substance, including Rh metal (suffering from a broad and very temperature-dependent signal), and Rh(acac) 3 , which has a long T 1 . Using these compounds is not a very sensible or practical way of referencing nowadays.…”

Section: General Aspects and Spectral Referencementioning

confidence: 99%

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¹⁰³Rh NMR spectroscopy and its application to rhodium chemistry

Ernsting

Gaemers

Elsevier

2004

Magnetic Reson in Chemistry

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Rhodium is used for a number of large processes that rely on homogeneous rhodium-catalyzed reactions, for instance rhodium-catalyzed hydroformylation of alkenes, carbonylation of methanol to acetic acid and hydrodesulfurization of thiophene derivatives (in crude oil). Many laboratory applications in organometallic chemistry and catalysis involve organorhodium chemistry and a wealth of rhodium coordination compounds is known. For these and other areas, 103Rh NMR spectroscopy appears to be a very useful analytical tool. In this review, most of the literature concerning 103Rh NMR spectroscopy published from 1989 up to and including 2003 has been covered. After an introduction to several experimental methods for the detection of the insensitive 103Rh nucleus, a discussion of factors affecting the transition metal chemical shift is given. Computational aspects and calculations of chemical shifts are also briefly addressed. Next, the application of 103Rh NMR in coordination and organometallic chemistry is elaborated in more detail by highlighting recent developments in measurement and interpretation of 103Rh NMR data, in relation to rhodium-assisted reactions and homogeneous catalysis. The dependence of the 103Rh chemical shift on the ligands at rhodium in the first coordination sphere, on the complex geometry, oxidation state, temperature, solvent and concentration is treated. Several classes of compounds and special cases such as chiral rhodium compounds are reviewed. Finally, a section on scalar coupling to rhodium is provided.

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Section: General Aspects and Spectral Referencementioning

confidence: 99%

“…3 ]. 56 The latter shows a υ 103 Rh of 2874 ppm, which is very different from the former at 642 ppm and is higher than for any other Rh(I) compound.…”

Section: Ligand Class and Donor Atommentioning

confidence: 99%

¹⁰³Rh NMR spectroscopy and its application to rhodium chemistry

Ernsting

Gaemers

Elsevier

2004

Magnetic Reson in Chemistry

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“…ii) Electronic effects could have large effects on catalyst reactivity. Because electronic effects have been shown to be important in asymmetric hydrogenation of enamides, [50] anion coordination could adjust the electronics of the metal center and favor certain diastereomeric intermediates or steps in the catalytic cycle.…”

Section: Rhmentioning

confidence: 99%

Probing the Mechanisms of Enantioselective Hydrogenation of Simple Olefins with Chiral Rhodium Catalysts in the Presence of Anions

Buriak¹,

Klein

Herrington

et al. 2000

Chem. Eur. J.

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The strong influence of various anions upon the hydrogenation of 2-phenyl-1-butene, catalyzed by chiral rhodium catalysts was investigated. Both sulfonates and halides exert large increases in the enantioselectivity when [Rh[(-)-bdpp](NBD)]ClO4 (bdpp = 2,4-bis(diphenylphosphino)pentane, NBD = 2,5-norbornadiene) is used as the catalyst precursor at high pressures (70 atm) of dihydrogen in nonpolar solvents. A dihydride mechanism similar to that for Wilkinson's catalyst [RhCl(PPh3)3] was shown to be operating at both high- and low-pressure conditions through a combination of catalytic studies, 31P, 1H and parahydrogen-induced polarization (PHIP) NMR experiments. With sulfonate and in neat methanol, however, a mechanistic switch takes place from a dihydride route (dihydrogen addition before olefin binding) at high pressure to an unsaturate route (olefin binding before dihydrogen addition) at low pressures (<30 atm). Olefin isomerization is inhibited by halide addition, but occurs with sulfonate and in neat methanol through what is most likely a pi-allyl mechanism. A detailed understanding of the effects of addition of these anions is crucial for development of new classes of catalysts capable of efficient enantioselective reduction of prochiral olefins lacking a secondary polar binding group.

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“…Although lo3Rh NMR spectra have been obtained by various techniques for some time now, as described in two major reviews (44,45), the method of obtaining rhodium chemical shifts via indirect 2D techniques has only recently been described and only a few examples of an indirect 3 1~, ' 0 3~h ( ' H ) NMR spectrum have been reported (46)(47)(48).…”

Section: Scheme 1 Schemementioning

confidence: 99%

Preparation and properties of rhodium(I) and iridium(I) diolefin complexes of heterodifunctional phosphorus–imine chelating ligands and a related iminophosphine. ¹⁰³Rh NMR parameters of the rhodium complexes obtained via indirect two-dimensional ³¹P, ¹⁰³Rh{¹H} NMR spectroscopy

Law¹,

Bigam²,

Cavell³

1995

Can. J. Chem.

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Transition metal NMR spectroscopy. Part XXIII. Rhodium-103 shielding and the stereoselectivity of dihydrogen (H2) addition to diastereomeric olefin complexes

Cited by 54 publications

References 0 publications

¹⁰³Rh NMR spectroscopy and its application to rhodium chemistry

¹⁰³Rh NMR spectroscopy and its application to rhodium chemistry

Probing the Mechanisms of Enantioselective Hydrogenation of Simple Olefins with Chiral Rhodium Catalysts in the Presence of Anions

Preparation and properties of rhodium(I) and iridium(I) diolefin complexes of heterodifunctional phosphorus–imine chelating ligands and a related iminophosphine. ¹⁰³Rh NMR parameters of the rhodium complexes obtained via indirect two-dimensional ³¹P, ¹⁰³Rh{¹H} NMR spectroscopy

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Transition metal NMR spectroscopy. Part XXIII. Rhodium-103 shielding and the stereoselectivity of dihydrogen (H2) addition to diastereomeric olefin complexes

Cited by 54 publications

References 0 publications

103Rh NMR spectroscopy and its application to rhodium chemistry

103Rh NMR spectroscopy and its application to rhodium chemistry

Probing the Mechanisms of Enantioselective Hydrogenation of Simple Olefins with Chiral Rhodium Catalysts in the Presence of Anions

Preparation and properties of rhodium(I) and iridium(I) diolefin complexes of heterodifunctional phosphorus–imine chelating ligands and a related iminophosphine. 103Rh NMR parameters of the rhodium complexes obtained via indirect two-dimensional 31P, 103Rh{1H} NMR spectroscopy

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¹⁰³Rh NMR spectroscopy and its application to rhodium chemistry

¹⁰³Rh NMR spectroscopy and its application to rhodium chemistry

Preparation and properties of rhodium(I) and iridium(I) diolefin complexes of heterodifunctional phosphorus–imine chelating ligands and a related iminophosphine. ¹⁰³Rh NMR parameters of the rhodium complexes obtained via indirect two-dimensional ³¹P, ¹⁰³Rh{¹H} NMR spectroscopy