1H‐ und 13C‐NMR‐Spektroskopie

The present state of the routine 1D ¹H‐ and ¹³C‐NMR spectroscopy is reported. After a short introduction into the basic theory the current spectrometer and software systems are discussed. Using an example from natural product chemistry the procedures during the analysis of the NMR spectra are explained.     

Polymorphie von Bis(dineopentoxyphosphorothioyl)diselenid – Korrelation von Röntgenstruktur und MAS‐NMR‐Daten

Polymorphism of Bis(dineopentoxyphosphorothioyl)diselenide – Correlation of X‐Ray Structure and MAS NMR Data The crystal structures of two polymorphs of the title compound were determined by single‐crystal X‐ray methods and refined both at room temperature and 250 K. A triclinic and a monoclinic phase were discovered and studied. Both modifications are centrosymmetrical layer structures. The numerically clearly significant differences were observed in unit cell volumes as well as in alternating disproportions of distances of atoms being chemically and crystallographically equivalent as a result of discontinuously distributed conformational changes along the single bonds. Phase transitions were not observed by cooling up to 240 K. Lowering temperatures single crystals of both phases decompose because of the considerable anisotropy of intermolecular interaction. The small differences of molecular structure produce slightly splitted ³¹P CP MAS NMR signals. A comparison of the chemical shifts from ¹³C CP MAS NMR spectra and from quantum‐chemical calculations leads to the conclusion that the inner rotation around CH₂–C_q bonds is not frozen in the solid state.     

Festkörper‐NMR‐Untersuchungen an Natriumoxothiophosphaten(V)

Solid State NMR Investigations on Sodium Oxothiophosphates(V) Sodium monothiophosphate(V) Na₃PO₃S is dimorphic. The metastable high temperature modification β‐Na₃PO₃S crystallizes hexagonal with a = 8.996(4) and c = 5.216(2)Å. According to ³¹P solid state NMR experiments, α‐Na₃PO₃S exhibits at 20 °C a non‐axial‐symmetric environment for the phosphorus nuclei in contrast to the results of the refined crystal structure. This discrepancy is discussed assuming ordered and disordered structural models. However, at 490 °C the chemical shift tensor of the phosphorus nuclei in α‐Na₃PO₃S is axial‐symmetric. So, the distortion of the phosphorus environment is abolished by the thermal motion of the atoms. The number of crystallographically distinguishable positions for phosphorus and for sodium in Na₃PO₂S₂ and Na₃POS₃ can be confirmed in good agreement with their crystal structures using solid state NMR spectroscopy.     

Complete assignment of NMR data of 22 phenyl‐1H‐pyrazoles' derivatives

Complete assignment of ¹H and ¹³C NMR chemical shifts and J(¹H/¹H and ¹H/¹⁹F) coupling constants for 22 1‐phenyl‐1H‐pyrazoles' derivates were performed using the concerted application of ¹H 1D and ¹H, ¹³C 2D gs‐HSQC and gs‐HMBC experiments. All 1‐phenyl‐1H‐pyrazoles' derivatives were synthesized as described by Finar and co‐workers. The formylated 1‐phenyl‐1H‐pyrazoles' derivatives were performed under Duff's conditions. Copyright © 2011 John Wiley & Sons, Ltd.     

Study of phenothiazine and N‐methyl phenothiazine by infrared,raman, 1H‐, and 13C‐NMR spectroscopies

A complete vibrational analysis of the Fourier transform (FT) infrared (IR) and FT‐Raman spectra of both molecules was carried out using quantum chemical calculations. The structure of phenothiazine (PTZ) and N‐methylphenothiazine (N‐MePTZ) were studied by semiempirical, and ab initio methods. Different basis sets and two new procedures for scaling the frequencies of the ring modes were used. Vibrational data of the methyl group in N‐MePTZ were interpreted in terms of the different molecular conformations in the solid state. The ¹H‐ and ¹³C–nuclear magnetic resonance (NMR) data were interpreted in terms of the electron densities on the atoms and the stacking solute–solute association in dimethyl sulfoxide solution. Chemical shifts were related to the Merz‐Kollman atomic charges. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002