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This occurs most frequently in compounds that contain phosphorus or fluorine, as they are both spin-1/2 nuclei of 100% abundance. For example, the 1H signals for the protons in fluoromethane are split into a doublet by the fluorine atom; conversely, the fluorine-19 NMR spectrum of this compound shows a quartet due to being split by the three ...
SDBS includes 14700 1 H NMR spectra and 13000 13 C NMR spectra as well as FT-IR, Raman, ESR, and MS data. The data are stored and displayed as an image of the processed data. Annotation is achieved by a list of the chemical shifts correlated to letters which are also used to label a molecular line drawing.
Bruker 700 MHz nuclear magnetic resonance (NMR) spectrometer. Nuclear Magnetic Resonance (NMR) basic principles. Nuclear magnetic resonance (NMR) is a physical phenomenon in which nuclei in a strong constant magnetic field are disturbed by a weak oscillating magnetic field (in the near field [1]) and respond by producing an electromagnetic signal with a frequency characteristic of the magnetic ...
NMR-active nuclei, particularly those with a spin quantum number of 1/2, are of great significance in NMR spectroscopy. Examples include 1 H, 13 C, 15 N, and 31 P. [10] Some atoms with very high spin (as 9/2 for 99 Tc atom) are also extensively studied with NMR spectroscopy. [11]
If a spectrum of an unknown chemical compound is available, a reverse search can be carried out by entering the values of the chemical shift, frequency or mass of the peaks in the NMR, FT-IR or EI-MS spectrum respectively. This type of search affords all the chemical compounds in the database that have the entered spectral characteristics. [6]
Phosphorus is commonly found in organic compounds and coordination complexes (as phosphines), making it useful to measure 31 - NMR spectra routinely. Solution 31 P-NMR is one of the more routine NMR techniques because 31 P has an isotopic abundance of 100% and a relatively high gyromagnetic ratio. The 31 P nucleus also has a spin of 1 / 2 ...
The 19 F NMR chemical shifts span a range of about 800 ppm. For organofluorine compounds the range is narrower, being about −50 to −70 ppm (for CF 3 groups) to −200 to −220 ppm (for CH 2 F groups). The very wide spectral range can cause problems in recording spectra, such as poor data resolution and inaccurate integration.
Although ca. 1 mln. times less sensitive than 1 H NMR spectroscopy, 13 C NMR spectroscopy is widely used for characterizing organic and organometallic compounds, primarily because 1H-decoupled 13C-NMR spectra are more simple, have a greater sensitivity to differences in the chemical structure, and, thus, are better suited for identifying ...