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1D Experiments

2D Experiments

The equipment of both the 600 MHz and 400 MHz instruments allows for a large variety of one-dimensional experiments in the automatic mode. The most important routine parameter sets are shown in the following table.

In principal, 1H coupled as well as 1H decoupled nmr spectra can be recorded for all nuclei with a frequency between that of 109Ag und 31P. Quadrupolar nuclei (spin >1/2) in an asymmetric non-cubic electronic environment will cause problems due to short relaxation times and thus broad lines. While the broadening is not very severe for light nuclei such as 7Li or 11B, spectra of nulcei with large quadrupole moments may have line widths of several thousand Hz.

Spectra of nuclei with a low and/or negative gyromagnetic ratio are best recorded indirectly (via 1H 2D spectra) or directly using polarization transfer from 1H or 19F via DEPT or INEPT which, however, requires a known or estimated coupling constant.

For many nuclei the range of chemical shifts clearly exceeds the maximum sweep width, that is, the expected chemical shift should be stated in the application form. This is also true for 13C spectra of inorganic carbonyl complexes with shifts > 200 ppm or organometallics with negative 13C shifts.

In case of very low concentrations a standard 13C spectrum will yield little or no information. Recording a 2D 1H/13C correlation (HSQC and/or HMBC) will give much better results due to the higher sensitivity of the 1H nucleus. Furthermore, additional structural information is supplied.

Standard 1D Experiments
NS** Time
                                       Comment                                                                               ;  
1HPROTON20.7162 Standard proton spectrum, 16.5 ppm to -4 ppm
1HWATER20.7164 A standard proton spectrum is recorded first, and the strongest peak, nomally water, is picked. The peak is eliminated by continous irradiation or special puls techniques.
13CC13CPD238102442 Standard 13C spectrum, 1H CPD decoupled , 285 to -40 ppm.
Based on the quality of the preceding 1H spectrum, the number of scans is reduced to 256 (conc. solutions), increased to 4096 (weekends) or cancelled (weekdays).
The spectrum is referenced automatically to the deuterated solvent.
13CC13DEPT13523825611 Parameters are transferred from the preceding 13C spectrum.
CH and CH3 groups are positively, CH2 groups negatively phased.
Quaterny C atoms are not observed.
13CC13DEPT452381286 CH, CH2 and CHresonances have the same phase.
Quaterny C atoms are not observed .
13CC13DEPT9023825611 Only CH groups are observed.
13CC13GD238102442 Proton coupled 13C spectrum with intensity increase by NOE.
31PP31CPD400322 1H CPD decoupled 31P spectrum
31PP31400322 1H coupled 31P spectrum 
19FF19200161 1H coupled 19F spectrum 
19FF19CPD265161 1H CPD decoupled 19F spectrum 
19FF19_1H2651610 19F survey spectrum (for sweep optimization) + 19F + 19F{1H} + 1H{19F} + 1H

* Spectral width (SW) of the survey spectrum
**Number of accumulated spectra (scans, NS)

2D Experiments