Abstract
The two‐dimensional nuclear magnetic resonance (NMR) correlation spectroscopy (COSY) and double quantum‐filtered COSY (DQF‐COSY) spectra of an AMX and an AX~2~ systems of spins I = 7/2 have been calculated by numerical density matrix calculations. The results are presented in three extreme cases, namely in the slow relaxation regime, the intermediate relaxation regime, and in the fast relaxation regime. It is concluded for such spin systems, as was recently shown in the case of an AX system of spins I = 3/2, that in addition to the usual advantages that the DQF‐COSY NMR experiment offer compared to the conventional COSY NMR experiment (observation of only‐coupled spins, antiphase character of both diagonal and cross‐peaks, and intensity of the cross‐peaks comparable to the intensity of the diagonal peaks), the DQF‐COSY NMR experiment appear to be more powerful for observation, interpretation, and analysis than the conventional COSY NMR experiment, and this is particularly true for quadrupolar nuclei relaxing usually very quickly and/or small coupling constants. © 2011 Wiley Periodicals, Inc. Concepts Magn Reson Part A 38A: 74–83, 2011.