scholarly journals Ab initio computation for solid-state 31P NMR of inorganic phosphates: revisiting X-ray structures

2019 ◽  
Vol 21 (19) ◽  
pp. 10070-10074 ◽  
Author(s):  
Kartik Pilar ◽  
Zeyu Deng ◽  
Molleigh B. Preefer ◽  
Joya A. Cooley ◽  
Raphaële Clément ◽  
...  
Keyword(s):  
Solid State ◽  
Chemical Shift ◽  
Ab Initio ◽  
Crystal Structures ◽  
31P Nmr ◽  
Geometry Optimization ◽  
Chemical Shift Tensors ◽  
X Ray ◽  
Ab Initio Computation ◽  
Inorganic Phosphates

The complete 31P NMR chemical shift tensors for 22 inorganic phosphates obtained from ab initio computation are found to correspond closely to experimentally obtained parameters. The cases where correspondence is significantly improved upon geometry optimization point to the crystal structures requiring correction.

Local-structure effects on 31P NMR chemical shift tensors in solid state

2019 ◽  
Vol 150 (14) ◽  
pp. 144706 ◽  
Author(s):  
Ivan Yu. Chernyshov ◽  
Mikhail V. Vener ◽  
Ilya G. Shenderovich
Keyword(s):  
Solid State ◽  
Chemical Shift ◽  
Local Structure ◽  
31P Nmr ◽  
Nmr Chemical Shift ◽  
Chemical Shift Tensors

Are the amide bonds in N-acyl imidazoles twisted? A combined solid-state 17O NMR, crystallographic, and computational study

2015 ◽  
Vol 93 (4) ◽  
pp. 451-458 ◽  
Author(s):  
Xianqi Kong ◽  
Aaron Tang ◽  
Ruiyao Wang ◽  
Eric Ye ◽  
Victor Terskikh ◽  
...  
Keyword(s):  
Solid State ◽  
Chemical Shift ◽  
Crystal Structures ◽  
Computational Study ◽  
Chemical Shifts ◽  
Amide Bond ◽  
Chemical Shift Tensors ◽  
Amide Bonds ◽  
Bond Rotation ◽  
Quadrupole Coupling

We report synthesis of 17O-labeling and solid-state 17O NMR measurements of three N-acyl imidazoles of the type R-C(17O)-Im: R = p-methoxycinnamoyl (MCA-Im), R = 4-(dimethylamino)benzoyl (DAB-Im), and R = 2,4,6-trimethylbenzoyl (TMB-Im). Solid-state 17O NMR experiments allowed us to determine for the first time the 17O quadrupole coupling and chemical shift tensors in this class of organic compounds. We also determined the crystal structures of these compounds using single-crystal X-ray diffraction. The crystal structures show that, while the C(O)–N amide bond in DAB-Im exhibits a small twist, those in MCA-Im and TMB-Im are essentially planar. We found that, in these N-acyl imidazoles, the 17O quadrupole coupling and chemical shift tensors depend critically on the torsion angle between the conjugated acyl group and the C(O)–N amide plane. The computational results from a plane-wave DFT approach, which takes into consideration the entire crystal lattice, are in excellent agreement with the experimental solid-state 17O NMR results. Quantum chemical computations also show that the dependence of 17O NMR parameters on the Ar–C(O) bond rotation is very similar to that previously observed for the C(O)–N bond rotation in twisted amides. We conclude that one should be cautious in linking the observed NMR chemical shifts only to the twist of the C(O)–N amide bond.

Probing solid iminobis(diorganophosphine chalcogenide) systems with multinuclear magnetic resonance

2009 ◽  
Vol 87 (1) ◽  
pp. 348-360 ◽  
Author(s):  
Bryan A Demko ◽  
Roderick E Wasylishen
Keyword(s):  
Solid State ◽  
Chemical Shift ◽  
Solid State Nmr ◽  
Magnetic Shielding ◽  
Chemical Shift Tensors ◽  
X Ray ◽  
X Ray Crystallography ◽  
Shielding Tensor ◽  
Nuclear Magnetic Shielding Tensors ◽  
Nuclear Magnetic

A 31P and 77Se solid-state NMR investigation of the iminobis(diorganophosphine chalcogenide) HN(R2PE)2 (R = Ph,iPr; E = O, S, Se) systems is presented. The NMR results are discussed in terms of the known HN(R2PE)2 structures available from X-ray crystallography. The phosphorus chemical shift tensors are found to be sensitive to the nature of the alkyl and chalcogen substituents. The nature of the R group also influences the selenium chemical shift tensors of HN(R2PSe)2 (R = Ph, iPr), which are shown to be sensitive to hydrogen bonding in the dimer structure of HN(Ph2PSe)2 and to the presence of disorder in the case of HN(iPr2PSe)2. Scalar relativistic ZORA DFT nuclear magnetic shielding tensor calculations were performed yielding the orientations of the corresponding chemical shift tensors. A theoretical investigation into the effect of the E-P···P-E “torsion” angle on the phosphorus and selenium chemical shift tensors of a truncated HN(Me2PSe)2 system indicates that the electronic effect of the alkyl group on the respective nuclear magnetic shielding tensors are more important than the steric effect of the E-P···P-E torsion angle.Key words: iminobis(diorganophosphine chalcogenide), solid-state NMR, 31P NMR, 77Se NMR, ZORA DFT.

A solid-state 13C NMR and theoretical investigation of carbonyl and thiocarbonyl carbon chemical shift tensors

1995 ◽  
Vol 73 (4) ◽  
pp. 604-613 ◽  
Author(s):  
Christopher W. Kirby ◽  
Michael D. Lumsden ◽  
Roderick E. Wasylishen
Keyword(s):  
Solid State ◽  
Chemical Shift ◽  
Ab Initio ◽  
Principal Axis ◽  
Comparative Investigation ◽  
Conclusive Evidence ◽  
Carbon Nucleus ◽  
Chemical Shift Tensors ◽  
Carbon Chemical Shift ◽  
C Nmr

The carbon chemical shift tensors of the carbonyl and thiocarbonyl groups of acetamide, thioacetamide, thioacetanilide, 4′-methoxyacetanilide, and 4′-methoxythioacetanilide have been experimentally determined using dipolar – chemical shift solid-state 13C NMR spectroscopy. The magnitudes of the three principal components of the carbon chemical shift tensors are found to exhibit marked variations between the carbonyl and thiocarbonyl functionalities. However, in contrast to the conclusions of an earlier comparative investigation involving benzophenone and thiobenzophenone, the orientations of the principal axis systems of these chemical shift tensors are found to be similar. These experimental results represent the first complete characterizations of the carbon chemical shift tensor in organic thiocarbonyls. The results of our ab initio GIAO and LORG calculations of carbon chemical shielding tensors in formaldehyde, thioformaldehyde, formamide, and thioformamide as well as in acetamide and thioacetamide are in qualitative agreement with experiment. The findings of the present investigation provide conclusive evidence that the well-known isotropic deshielding of the carbon nucleus in the C=S group relative to C=O is primarily attributable to the decreased energy associated with the σ ↔ π* excitation within the thiocarbonyl fragment. This result is in contrast with the conventional interpretation that the deshielding originates from a red shift in the C=S HOMO–UMO n → π* transition. Keywords: chemical shift tensors, solid-state 13C NMR, carbonyls, thiocarbonyls, ab initio calculations.

Bis(1-phenyl-1-propyne) complexes of tungsten(II): crystal structures of [WI2(CO)(NCR)(η2-MeC2Ph)2] (R = Me, Et, or Ph)

2001 ◽  
Vol 79 (3) ◽  
pp. 263-271
Author(s):  
Paul K Baker ◽  
Michael GB Drew ◽  
Deborah S Evans
Keyword(s):  
Carbon Monoxide ◽  
Solid State ◽  
Crystal Structures ◽  
Octahedral Geometry ◽  
X Ray ◽  
X Ray Crystallography ◽  
Alkyne Complexes ◽  
First Time

Reaction of [WI2(CO)3(NCMe)2] with two equivalents of 1-phenyl-1-propyne (MeC2Ph) in CH2Cl2, and in the absence of light, gave the bis(1-phenyl-1-propyne) complex [WI2(CO)(NCMe)(η2-MeC2Ph)2] (1) in 77% yield. Treatment of equimolar quantities of 1 and NCR (R = Et, i-Pr, t-Bu, Ph) in CH2Cl2 afforded the nitrile-exchanged products, [WI2(CO)(NCR)(η2-MeC2Ph)2] (2-5) (R = Et (2), i-Pr (3), t-Bu (4), Ph (5)). Complexes 1, 2, and 5 were structurally characterized by X-ray crystallography. All three structures have the same pseudo-octahedral geometry, with the equatorial sites being occupied by cis and parallel alkyne groups, which are trans to the cis-iodo groups. The trans carbon monoxide and acetonitrile ligands occupy the axial sites. In structures 1 and 2, the methyl and phenyl substituents of the 1-phenyl-1-propyne ligands are cis to each other, whereas for the bulkier NCPh complex (5), the methyl and phenyl groups are trans to one another. This is the first time that this arrangement has been observed in the solid state in bis(alkyne) complexes of this type.Key words: bis(1-phenyl-1-propyne), carbonyl, nitrile, diiodo, tungsten(II), crystal structures.

scholarly journals NOTIZEN. Weitere Verbindungen vom Typ A3NO3: K3NO3 und Rb3NO3 / Further Compounds Typ A3NO3: K3NO3 and Rb3NO3

1980 ◽  
Vol 35 (2) ◽  
pp. 237-238 ◽  
Author(s):  
Martin Jansen
Keyword(s):  
Solid State ◽  
Crystal Structures ◽  
Solid State Reaction ◽  
X Ray

Abstract K3NO3 and RbsNO3 were prepared by solid state reaction of equimolar mixtures of K2O/KNO2 and Rb20/RbN02, respectively. According to X-ray powder photographs their crystal structures are derived from the perovs-kite structure. K3NO3 is isostructural with Na3NO3 (a = 521.7 pm, Z = 1), Rb3NO3 represents a tetragonally distorted variant with a = 770.5, c = 550.8 pm and Z = 2.

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