Phosphorus-31 NMR studies of several phosphines in the solid state

1989 ◽  
Vol 67 (11) ◽  
pp. 1909-1913 ◽  
Author(s):  
Glenn H. Penner ◽  
Roderick E. Wasylishen
Keyword(s):  
Chemical Shift ◽  
Principal Components ◽  
Chemical Shift Tensor ◽  
Cross Polarization ◽  
X Ray Diffraction ◽  
Nmr Studies ◽  
Chemical Shift Tensors ◽  
X Ray ◽  
Cp Mas Nmr ◽  
Proton Decoupling

Phosphorus-31 NMR powder spectra and high resolution MAS spectra have been obtained for a number of solid phosphines under conditions of high-power proton decoupling and cross-polarization. The principal components of the 31P chemical shift tensor obtained from static powder spectra or slow MAS spectra are discussed in terms of the known structures of many of the phosphines. The CP/MAS 31PNMR spectra are used to determine the number of crystallographically nonequivalent molecules in the unit cell. The NMR results are consistent with data available from X-ray diffraction. In one case there is evidence of polymorphism. Keywords: 31P NMR of solid phosphines, principal components of 31P chemical shift tensors, crystallographic nonequivalence from 31P CP/MAS NMR.

scholarly journals Conversion of sub-µm calcium carbonate (calcite) particles to hollow hydroxyapatite agglomerates in K2HPO4 solutions

2020 ◽  
Vol 9 (1) ◽  
pp. 945-960
Author(s):  
Sun Yanyan ◽  
Wang Guangxin ◽  
Li Wuhui ◽  
Wang Yaming ◽  
Satoshi Hayakawa ◽  
...  
Keyword(s):  
Activation Energy ◽  
Magic Angle Spinning ◽  
Magic Angle ◽  
Cross Polarization ◽  
X Ray Diffraction ◽  
Nmr Studies ◽  
X Ray ◽  
Order Of Magnitude ◽  
Angle Spinning ◽  
Cp Mas Nmr

AbstractSub-µm CaCO3 (calcite; CC) particles were converted to calcium monohydrogenphosphate dihydrate (DCPD) and hydroxyapatite (HAp) via soaking treatments in K2HPO4 solutions with varied pH (3–12) and concentrations (0.1–1.5 M) at 37°C for up to 10 days. DCPD was derived from the solutions with pH ≤ 6; while hollow HAp was yielded when pH ≥ 7 in assemblies of petal-like crystallites. Results of magic angle spinning (MAS) and cross-polarization magic angle spinning (CP-MAS) NMR studies have shown that the HAp lattice has only PO42− but no HPO42− at B (phosphate) sites. Trace amounts of CO32− have occupied both A (OH) and B (PO4) sites, and H2O is adsorbed on surface crystallites. The primary crystallite size of HAp derived from Scherrer equation increases quickly in a 12 h period and becomes gradually stable afterward. Samples of particles soaked within 3 h in a temperature range of 20–80°C were analyzed by X-ray diffraction. It is shown that the rate constant of 1 M solution is about an order of magnitude greater than that of 0.1 M solution and the apparent activation energy is 33 kJ/mol. In this work, the conversion of CC to HAp can be quantitatively controlled to solve the problem of slow degradation of HAp.

scholarly journals Linear dicoordinate beryllium: a 9Be solid-state NMR study of a discrete zero-valent s-block beryllium complex

2018 ◽  
Vol 96 (7) ◽  
pp. 646-652 ◽  
Author(s):  
C. Leroy ◽  
J.K. Schuster ◽  
T. Schaefer ◽  
K. Müller-Buschbaum ◽  
H. Braunschweig ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Solid State ◽  
Chemical Shift ◽  
Solid State Nmr ◽  
Chemical Shift Tensor ◽  
X Ray Diffraction ◽  
X Ray ◽  
Quadrupolar Coupling ◽  
Nmr Study ◽  
Tensor Data

Beryllium-9 (9Be) quadrupolar coupling and chemical shift tensor data are reported for bis(1-(2,6-diisopropylphenyl)-3,3,5,5-tetramethylpyrrolidine-2-ylidene)beryllium (Be(CAAC)2). These are the first such data for beryllium in a linear dicoordinate environment. The 9Be quadrupolar coupling constant, 2.36(0.02) MHz, is the largest recorded in the solid state to date for this isotope. The span of the beryllium chemical shift tensor, 22(2) ppm, covers about half of the known 9Be chemical shift range, and the isotropic 9Be chemical shift, 32.0(0.3) ppm, is the largest reported in the solid state to our knowledge. DFT calculations reproduce the experimental data well. A natural localized molecular orbital approach has been used to explain the origins and orientation of the beryllium electric field gradient tensor. The single-crystal X-ray structure of a second polymorph of Be(CAAC)2 is also reported. Inspection of the powder X-ray diffraction data shows that the new crystal structure is part of the bulk product next to another crystalline phase. Therefore, experimental X-ray powder data for the microcrystalline powder sample and the SSNMR data do not fully match either the originally reported crystal structure (Arrowsmith et al. Nat. Chem. 2016, 8, 890–894) or the new polymorph. The ability of solid-state NMR and powder X-ray diffraction to characterize powdered samples was thus particularly useful in this work.

scholarly journals A phosphorus-31 NMR study of solid carbonylhydridotris(triphenylphosphine)rhodium(I). Unusual MAS sideband intensities in second-order NMR spin systems

1992 ◽  
Vol 70 (3) ◽  
pp. 863-869 ◽  
Author(s):  
Gang Wu ◽  
Roderick E. Wasylishen ◽  
Ronald D. Curtis
Keyword(s):  
Chemical Shift ◽  
Spin System ◽  
Principal Components ◽  
Nmr Spectra ◽  
Magic Angle Spinning ◽  
Chemical Shift Tensor ◽  
Magic Angle ◽  
Nmr Spectrum ◽  
Chemical Shift Tensors ◽  
Nmr Study

The CP/MAS 31P NMR spectrum of carbonylhydridotris(triphenylphosphine)rhodium(I), RhH(CO)(PPh3)3 (1), can be described as a tightly coupled ABMX spin system (X = 103Rh). In contrast to the solution 31P NMR spectrum, the three equatorial phosphorus nuclei are nonequivalent in the solid state and this structural feature allows us to measure the two-bond spin–spin couplings, 2J(31P,31P). A new method is proposed for extracting the principal components of the chemical shift tensor from slow MAS NMR spectra in a tightly J-coupled two-spin system. For compound 1, the principal components of the 31P chemical shift tensors calculated using this method are in good agreement with those obtained from NMR spectra of a static sample. The principal components of the 31P chemical shift tensors determined for 1 are compared with those reported previously for Wilkinson's catalyst, RhCl(PPh3)3. The δ22 component of the 31P chemical shift tensors in 1 shows the largest variation with structure. This is ascribed to differences in the orientation of the P—Cipso bond about the equatorial plane of the trigonal bipyramidal structure. Keywords: rhodium–phosphine compounds, AB spin system, 31P chemical shift tensor, magic-angle spinning, molecular structure.

X-ray diffraction, Raman spectroscopic, and solid-state NMR studies of the group 14 metal-(tetracarbonyl)cobalt complexes Ph3MCo(CO)4 (M = Si, Sn, Pb)

2002 ◽  
Vol 80 (7) ◽  
pp. 813-820 ◽  
Author(s):  
J M Geller ◽  
J H Wosnick ◽  
I S Butler ◽  
D FR Gilson ◽  
F G Morin ◽  
...  
Keyword(s):  
Solid State ◽  
Spin Coupling ◽  
Chemical Shift Tensor ◽  
Coupling Constant ◽  
X Ray Diffraction ◽  
Group 14 ◽  
X Ray ◽  
Fermi Contact ◽  
Spin Spin Coupling ◽  
Cp Mas Nmr

Single-crystal X-ray diffraction studies illustrate that the three title compounds are isomorphous, belonging to the triclinic space group P[Formula: see text], with slightly distorted trigonal bipyramidal geometry about cobalt. The solid-state 29Si, 119Sn, and 207Pb cross-polarization magic angle spinning (CP MAS) NMR spectra are presented. The indirect spin–spin coupling constant (J), quadrupolar–dipolar shift (d), direct dipolar coupling constant (D' ), anisotropy in spin–spin coupling (ΔJ), and the chemical shift tensor were extracted. A plot of the reduced coupling constant vs. s-electron densities at the nucleus indicates that the Fermi contact term may be dominant for the tin and lead complexes; however, the large ΔJ for all complexes indicate that there are also significant anisotropic terms. Trends in the Raman scattering spectra are also discussed.Key words: 29Si, 119Sn, and 207Pb CP MAS NMR, tetracarbonyl cobalt, spin–spin coupling, chemical shift tensor, quadrupole coupling, Fermi contact, cobalt–group 14.

Molecular Modeling, X-ray Diffraction, and 13C,77Se CP/MAS NMR Studies of Bis(2,3,4,6-tetra-O-acetyl-.beta.-D-glucopyranosyl) Diselenide and Disulfide

1995 ◽  
Vol 60 (10) ◽  
pp. 3139-3148 ◽  
Author(s):  
Marek J. Potrzebowski ◽  
Maria Michalska ◽  
Jaroslaw Blaszczyk ◽  
Michal W. Wieczorek ◽  
Wlodzimierz Ciesielski ◽  
...  
Keyword(s):  
Molecular Modeling ◽  
Mas Nmr ◽  
X Ray Diffraction ◽  
Nmr Studies ◽  
X Ray ◽  
Cp Mas Nmr

Tetraphenyl-and tetratolylantimony complexes with N,N-dialkyldithiocarbamate ligands: Synthesis, X-ray diffraction analysis, and 13C and 15N CP/MAS NMR studies

2006 ◽  
Vol 32 (6) ◽  
pp. 387-396 ◽  
Author(s):  
V. V. Sharutin ◽  
M. A. Ivanov ◽  
A. V. Gerasimenko ◽  
A. V. Ivanov ◽  
A. P. Pakusina ◽  
...  
Keyword(s):  
Diffraction Analysis ◽  
Mas Nmr ◽  
X Ray Diffraction ◽  
Nmr Studies ◽  
X Ray ◽  
Cp Mas Nmr

New Copper Compounds with Antiplatelet Aggregation Activity

2019 ◽  
Vol 15 (8) ◽  
pp. 850-862
Author(s):  
Mirthala Flores-García ◽  
Juan Manuel Fernández-G. ◽  
Cristina Busqueta-Griera ◽  
Elizabeth Gómez ◽  
Simón Hernández-Ortega ◽  
...  
Keyword(s):  
Schiff Base ◽  
Solid State ◽  
Thrombotic Event ◽  
X Ray Diffraction ◽  
Nmr Studies ◽  
Schiff Base Ligands ◽  
X Ray ◽  
Antiplatelet Aggregation ◽  
Aggregation Activity ◽  
L1 And L2

Background: Ischemic heart disease, cerebrovascular accident, and venous thromboembolism have the presence of a thrombotic event in common and represent the most common causes of death within the population. Objective: Since Schiff base copper(II) complexes are able to interact with polyphosphates (PolyP), a procoagulant and potentially prothrombotic platelet agent, we investigated the antiplatelet aggregating properties of two novel tridentate Schiff base ligands and their corresponding copper( II) complexes. Methods: The Schiff base ligands (L1) and (L2), as well as their corresponding copper(II) complexes (C1) and (C2), were synthesized and characterized by chemical analysis, X-ray diffraction, mass spectrometry, and UV-Visible, IR and far IR spectroscopy. In addition, EPR studies were carried out for (C1) and (C2), while (L1) and (L2) were further analyzed by 1H and 13C NMR. Tests for antiplatelet aggregation activities of all of the four compounds were conducted. Results: X-ray diffraction studies show that (L1) and (L2) exist in the enol-imine tautomeric form with a strong intramolecular hydrogen bond. NMR studies show that both ligands are found as enol-imine tautomers in CDCl3 solution. In the solid state, the geometry around the copper(II) ion in both (C1) and (C2) is square planar. EPR spectra suggest that the geometry of the complexes is similar to that observed in the solid state by X-ray crystallography. Compound (C2) exhibited the strongest antiplatelet aggregation activity. Conclusion: Schiff base copper(II) complexes, which are attracting increasing interest, could represent a new approach to treat thrombosis by blocking the activity of PolyP with a potential anticoagulant activity and, most importantly, demonstrating no adverse bleeding events.

scholarly journals Chemical-shift tensors of heavy nuclei in network solids: a DFT/ZORA investigation of 207Pb chemical-shift tensors using the bond-valence method

2015 ◽  
Vol 17 (38) ◽  
pp. 25014-25026 ◽  
Author(s):  
Fahri Alkan ◽  
C. Dybowski
Keyword(s):  
Chemical Shift ◽  
Quantum Chemistry ◽  
Principal Components ◽  
Bond Valence ◽  
Cluster Models ◽  
Magnetic Shielding ◽  
Heavy Nuclei ◽  
Chemical Shift Tensors ◽  
Accurate Computation ◽  
Bond Valence Model

Accurate computation of 207Pb magnetic shielding principal components is within the reach of quantum chemistry methods by employing relativistic ZORA/DFT and cluster models adapted from the bond valence model.

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