1D 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.