New Mechanistic Insights Regarding Pd/Cu Catalysts for the Sonogashira Reaction:  HRMAS NMR Studies of Silica-Immobilized Systems

Posset, Tobias; Blümel, Janet

doi:10.1021/ja062206r

Cited by 74 publications

(42 citation statements)

References 16 publications

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“…Owing to these favorable properties several studies of immobilized species on surfaces employing modern techniques of solidstate NMR are reported in the literature. [23,[52][53][54] In this work we use a combination of 29 Si and advanced 31 P solid-state NMR methods to investigate and characterize modified surface of mesoporous silica and to study the exact binding of Wilkinsons complex to the modified silica surface. We demonstrate that the 31 P J-resolved 2D slow-spinning magic-angle-spinning (MAS) and Off-MAS 31 P NMR techniques are efficient tools to reveal the detailed binding situation of the supported [RhClA C H T U N G T R E N N U N G (PPh 3 ) 3 ] molecule.…”

Section: Introductionmentioning

confidence: 99%

Solid‐State NMR Characterization of Wilkinson’s Catalyst Immobilized in Mesoporous SBA‐3 Silica

Grünberg

Breitzke

et al. 2010

Chemistry A European J

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The Wilkinson's catalyst [RhCl(PPh(3))(3)] has been immobilized inside the pores of amine functionalized mesoporous silica material SBA-3 and The structure of the modified silica surface and the immobilized rhodium complex was determined by a combination of different solid-state NMR methods. The successful modification of the silica surface was confirmed by (29)Si CP-MAS NMR experiments. The presence of the T(n) peaks confirms the successful functionalization of the support and shows the way of binding the organic groups to the surface of the mesopores. (31)P-(31)P J-resolved 2D MAS NMR experiments were conducted in order to characterize the binding of the immobilized catalyst to the amine groups of the linkers attached to the silica surface. The pure catalyst exhibits a considerable (31)P-(31)P J-coupling, well resolvable in 2D MAS NMR experiments. This J-coupling was utilized to determine the binding mode of the catalyst to the linkers on the silica surface and the number of triphenylphosphine ligands that are replaced by coordination bonds to the amine groups. From the absence of any resolvable (31)P-(31)P J-coupling in off-magic-angle-spinning experiments, as well as slow-spinning MAS experiments, it is concluded, that two triphenylphosphine ligands are replaced and that the catalyst is bonded to the silica surface through two linker molecules.

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Section: Introductionmentioning

confidence: 99%

Solid‐State NMR Characterization of Wilkinson’s Catalyst Immobilized in Mesoporous SBA‐3 Silica

Grünberg

Breitzke

et al. 2010

Chemistry A European J

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“…Compounds of the formula (R 2 PCH 2 ) 2 N(R) and {(R 2 PCH 2 ) 2 N} 2 (R) are two such examples [6][7][8][9][10] which have interesting coordination properties, catalytic applications and, more recently, are important ligands for self-assembly reactions using covalent bonds or H-bonding interactions.…”

Section: Introductionmentioning

confidence: 99%

Mononuclear and Heterodinuclear Metal Complexes of Nonsymmetric Ditertiary Phosphanes Derived from R₂PCH₂OH

et al. 2007

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The new nonsymmetric ditertiary phosphanes, Ph 2 PCH 2 N-(R)CH 2 PAd [3a: R = C 6 H 5 , 3b: R = C 6 H 4 (4-CH 3 )] were prepared using a three-step sequence of condensation reactions. Hence treatment of AdP-H (AdP-H = 1,3,5,7-tetramethyl-2,4,8-trioxa-6-phosphaadamantane) with (CH 2 O) n at 110°C gave the adamantane-derived hydroxymethylphosphane 1, which upon condensation with C 6 H 5 NH 2 or C 6 H 4 (4-CH 3 )-NH 2 gave the secondary aminophosphanes HN(R)CH 2 PAd [2a: R = C 6 H 5 , 2b: R = C 6 H 4 (4-CH 3 )]. Further condensation of 2a or 2b with Ph 2 PCH 2 OH gave 3a or 3b in high yields

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“…One such system involves the catalytic addition of hydrogen in PASADENA. [70,71] This system is studied under higher than atmospheric pressures, though it is just a few atmospheres of pressure, and has both solids and liquids in it. Systems have been made in which this system could be studied, but they are quite elabrate and potentially very costly.…”

Section: High Pressure Rotor Design 921 Motivationmentioning

confidence: 99%

New Methodology For Use in Rotating Field Nuclear MagneticResonance

Jachmann

2007

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High-resolution NMR spectra of samples with anisotropic broadening are simplified to their isotropic spectra by fast rotation of the sample at the magic angle 54.7 • . This dissertation concerns the development of novel Nuclear Magnetic Resonance(NMR) methodologies which would rotate the magnetic field instead of the sample, i.e. rotating field NMR. It also provides an overview of the NMR concepts, procedures, and experiments needed to understand the methodologies that will be used for rotating field NMR.A simple two-dimensional shimming method based on harmonic corrector rings provides arbitrary multiple order shimming corrections that are necessary for rotating field systems, but can be used in shimming other systems as well. Those results demonstrate, for example, that quadrupolar order shimming improves the linewidth by up to a factor of ten. An additional order of magnitude reduction is in principle achievable by utilizing this shimming method for z-gradient correction and higher order xy gradients.Additionally, initial investigations into a specialized pulse sequence for the rotating field NMR experiment, which allows for spinning at angles other than the magic angle and spinning slower than the anisotropic broadening is discussed. This will be useful for rotating field NMR because there are limits on how fast a field can be spun and difficulties of reaching the magic angle. This pulse sequence is a combination of the previously established projected magic angle spinning (p-MAS) and magic angle turning (MAT) pulse sequences. One of the goals of this project is for rotating field NMR to be used on biological systems. The p-MAS pulse sequence was successfully tested on bovine tissue samples, which suggests that it will be a viable methodology to use in rotating field NMR.A side experiment on steering magnetic particles by MRI gradients was also carried out.Initial investigations indicate some movement, but for total steering control, further experiments are needed.1

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New Mechanistic Insights Regarding Pd/Cu Catalysts for the Sonogashira Reaction: HRMAS NMR Studies of Silica-Immobilized Systems

Cited by 74 publications

References 16 publications

Solid‐State NMR Characterization of Wilkinson’s Catalyst Immobilized in Mesoporous SBA‐3 Silica

Solid‐State NMR Characterization of Wilkinson’s Catalyst Immobilized in Mesoporous SBA‐3 Silica

Mononuclear and Heterodinuclear Metal Complexes of Nonsymmetric Ditertiary Phosphanes Derived from R₂PCH₂OH

New Methodology For Use in Rotating Field Nuclear MagneticResonance

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New Mechanistic Insights Regarding Pd/Cu Catalysts for the Sonogashira Reaction: HRMAS NMR Studies of Silica-Immobilized Systems

Cited by 74 publications

References 16 publications

Solid‐State NMR Characterization of Wilkinson’s Catalyst Immobilized in Mesoporous SBA‐3 Silica

Solid‐State NMR Characterization of Wilkinson’s Catalyst Immobilized in Mesoporous SBA‐3 Silica

Mononuclear and Heterodinuclear Metal Complexes of Nonsymmetric Ditertiary Phosphanes Derived from R2PCH2OH

New Methodology For Use in Rotating Field Nuclear MagneticResonance

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Mononuclear and Heterodinuclear Metal Complexes of Nonsymmetric Ditertiary Phosphanes Derived from R₂PCH₂OH