<sup>13</sup>C and <sup>23</sup>Na solid‐state NMR spectra of organosodium compounds

Jost, Steffen; Günther, Harald

doi:10.1002/mrc.1189

Cited by 11 publications

(5 citation statements)

References 30 publications

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“…In recent years solid-state NMR spectroscopy has become a useful tool for direct detection of alkali metal ions in a variety of organic and biological systems. − One important step toward useful applications of this methodology to unknown systems is to establish relationships between NMR spectral parameters of alkali metal ions and ion binding environment. Among cation−ligand interactions, cation−π interactions are of particular importance. − Several years ago, we reported solid-state 23 Na and 39 K NMR spectra for sodium and potassium tetraphenylborates, Na[BPh 4 ] and K[BPh 4 ] .…”

Section: Introductionmentioning

confidence: 99%

A Multinuclear Solid-State NMR Study of Alkali Metal Ions in Tetraphenylborate Salts, M[BPh₄] (M = Na, K, Rb and Cs): What Is the NMR Signature of Cation−π Interactions?

Terskikh

2008

J. Phys. Chem. A

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We report a multinuclear solid-state ( (23)Na, (39)K, (87)Rb, (133)Cs) NMR study of tetraphenylborate salts, M[BPh 4] (M = Na, K, Rb, Cs). These compounds are isostructural in the solid state with the alkali metal ion surrounded by four phenyl groups resulting in strong cation-pi interactions. From analyses of solid-state NMR spectra obtained under stationary and magic-angle spinning (MAS) conditions at 11.75 and 21.15 T, we have obtained the quadrupole coupling constants, C Q, and the chemical shift tensor parameters for the alkali metal ions in these compounds. We found that the observed quadrupole coupling constant for M (+) in M[BPh 4] is determined by a combination of nuclear quadrupole moment, Sternheimer antishielding factor, and unit cell dimensions. On the basis of a comparison between computed paramagnetic and diamagnetic contributions to the total chemical shielding values for commonly found cation-ligand interactions, we conclude that cation-pi interactions give rise to significantly lower paramagnetic shielding contributions than other cation-ligand interactions. As a result, highly negative chemical shifts are expected to be the NMR signature for cations interacting exclusively with pi systems.

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Section: Introductionmentioning

confidence: 99%

A Multinuclear Solid-State NMR Study of Alkali Metal Ions in Tetraphenylborate Salts, M[BPh₄] (M = Na, K, Rb and Cs): What Is the NMR Signature of Cation−π Interactions?

Terskikh

2008

J. Phys. Chem. A

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“…Solid-state NMR experiments, including those from the perspective of the central metal nucleus, have proven to be an ideal tool for characterizing alkali-metal metallocenes, including those in noncrystalline solids. Solid-state NMR studies of metal nuclei in polymeric metallocenes include a 7 Li NMR study of lithium metallocenes and other organometallic complexes, as well as 23 Na NMR studies of CpNa-TMEDA, an assortment of organosodium complexes, and a variety of Cp‘Na complexes …”

Section: Introductionmentioning

confidence: 99%

A Solid-State ³⁹K and ¹³C NMR Study of Polymeric Potassium Metallocenes

Widdifield

Schurko

2005

J. Phys. Chem. A

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The quadrupolar Carr-Purcell Meiboom-Gill (QCPMG) and double frequency sweep (DFS)/QCPMG pulse sequences are applied in order to acquire the first solid-state 39K NMR spectra of organometallic complexes, the polymeric main group metallocenes cyclopentadienyl potassium (CpK) and pentamethylcyclopentadienyl potassium (Cp*K). Piecewise QCPMG NMR techniques are used to acquire a high S/N 39K spectrum of the broad central transition of Cp*K, which is ca. 200 kHz in breadth. Analytical and numerical simulations indicate that there is a significant quadrupolar interaction present at both potassium nuclei (C(Q)(39K) = 2.55(6)/2.67(8) MHz and 4.69(8) MHz for CpK (static/MAS) and Cp*K, respectively). Experimental quadrupolar asymmetry parameters suggest that both structures are bent about the potassium atoms (eta(Q)(39K) = 0.28(3)/0.29(3) for CpK (static/MAS) and eta(Q)(39K) = 0.30(3) for Cp*K). Variable-temperature (VT) 39K NMR experiments on CpK elucidate temperature-dependent changes in quadrupolar parameters which can be rationalized in terms of alterations of bond distances and angles with temperature. 13C CP/MAS NMR experiments are conducted upon both samples to quantify the carbon chemical shielding anisotropy (CSA) at the Cp' ring carbon atoms. Ab initio carbon CSA and 39K electric-field gradient (EFG) and CSA calculations are conducted and discussed for the CpK complex, in order to correlate the experimental NMR parameters with molecular structure in CpK and Cp*K. 39K DFS/QCPMG and 13C CP/MAS experiments prove invaluable for probing molecular structure, temperature-dependent structural changes, and the presence of impurities in these systems.

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“…Beer and co-workers demonstrated the use of 205 Tl (spin 1 / 2 ) NMR in studying cation−π interactions in solution. For alkali metal cations, several solid-state 7 Li and 23 Na NMR studies have been reported dealing with metallocene compounds. − To establish solid-state 23 Na and 39 K NMR as a tool for probing cation−π interactions, one needs to obtain spectral signatures for such cation binding sites. Here we report a comprehensive solid-state NMR study of sodium and potassium tetraphenylborates, two earliest known compounds containing cation−π interactions.…”

Section: Introductionmentioning

confidence: 99%

A Solid-State NMR and Computational Study of Sodium and Potassium Tetraphenylborates: ²³Na and ³⁹K NMR Signatures for Systems Containing Cation−π Interactions

et al. 2004

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Sodium and potassium tetraphenylborates were examined by solid-state 23Na and 39K NMR spectroscopy. Analyses of solid-state NMR spectra obtained at 4.70, 11.75, and 19.60 T yielded the following 23Na and 39K NMR parameters: Na[BPh4], |C Q| = 1.24 ± 0.05 MHz, ηQ = 0.0 ± 0.1, δiso = −45.6 ± 0.5 ppm, and Ω = 14 ± 2 ppm; K[BPh4], |C Q| = 1.32 ± 0.05 MHz, ηQ = 0.0 ± 0.1, and δiso = −92 ± 1 ppm. In both Na[BPh4] and K[BPh4], the electric field gradient and chemical shift tensors at the metal site are axially symmetric, in agreement with the crystallographic symmetry. Extensive quantum mechanical calculations were performed for Na[BPh4] and K[BPh4] as well as for a large number of model cation−π systems containing Na+ and K+ ions and common aromatic compounds. Experimental and theoretical studies confirm that a highly shielded environment at the metal cation site is a characteristic feature for cation−π interactions, making it useful as a NMR signature for identifying cation−π interactions in proteins and nucleic acids. In this study, powder X-ray diffraction spectra for Na[BPh4] and K[BPh4] were also reported.

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¹³C and ²³Na solid‐state NMR spectra of organosodium compounds

Abstract: For three organosodium complexes, namely triphenylmethylsodium(tmeda) (1), fluorenylsodium(pmdta) (2) and fluorenylsodium(tmeda) (3), 13

Cited by 11 publications

References 30 publications

A Multinuclear Solid-State NMR Study of Alkali Metal Ions in Tetraphenylborate Salts, M[BPh₄] (M = Na, K, Rb and Cs): What Is the NMR Signature of Cation−π Interactions?

A Multinuclear Solid-State NMR Study of Alkali Metal Ions in Tetraphenylborate Salts, M[BPh₄] (M = Na, K, Rb and Cs): What Is the NMR Signature of Cation−π Interactions?

A Solid-State ³⁹K and ¹³C NMR Study of Polymeric Potassium Metallocenes

A Solid-State NMR and Computational Study of Sodium and Potassium Tetraphenylborates: ²³Na and ³⁹K NMR Signatures for Systems Containing Cation−π Interactions

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13C and 23Na solid‐state NMR spectra of organosodium compounds

Abstract: For three organosodium complexes, namely triphenylmethylsodium(tmeda) (1), fluorenylsodium(pmdta) (2) and fluorenylsodium(tmeda) (3), 13

Cited by 11 publications

References 30 publications

A Multinuclear Solid-State NMR Study of Alkali Metal Ions in Tetraphenylborate Salts, M[BPh4] (M = Na, K, Rb and Cs): What Is the NMR Signature of Cation−π Interactions?

A Multinuclear Solid-State NMR Study of Alkali Metal Ions in Tetraphenylborate Salts, M[BPh4] (M = Na, K, Rb and Cs): What Is the NMR Signature of Cation−π Interactions?

A Solid-State 39K and 13C NMR Study of Polymeric Potassium Metallocenes

A Solid-State NMR and Computational Study of Sodium and Potassium Tetraphenylborates: 23Na and 39K NMR Signatures for Systems Containing Cation−π Interactions

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¹³C and ²³Na solid‐state NMR spectra of organosodium compounds

A Multinuclear Solid-State NMR Study of Alkali Metal Ions in Tetraphenylborate Salts, M[BPh₄] (M = Na, K, Rb and Cs): What Is the NMR Signature of Cation−π Interactions?

A Multinuclear Solid-State NMR Study of Alkali Metal Ions in Tetraphenylborate Salts, M[BPh₄] (M = Na, K, Rb and Cs): What Is the NMR Signature of Cation−π Interactions?

A Solid-State ³⁹K and ¹³C NMR Study of Polymeric Potassium Metallocenes

A Solid-State NMR and Computational Study of Sodium and Potassium Tetraphenylborates: ²³Na and ³⁹K NMR Signatures for Systems Containing Cation−π Interactions