Improved multiplicity‐editing of HMBC NMR spectra

A new improved multiplicity‐edited HMBC experiment is introduced that leads to better J cross‐talk suppression in the even (i.e. C + CH2 groups) and odd (i.e. CH + CH3 groups) subspectra. By combining data recorded with three different pulse sequences J cross‐talk becomes a second‐order effect in Δ1J, i.e. the deviation of an actual 1J coupling constant from the value 1J0 used in setting delays τ = (1J0)−1/2, which is adequate for most applications. As for the original multiplicity‐edited HMBC experiment, the improved experiment can be performed with a single excitation delay or implemented in a broadband version similar to broadband HMBC. Copyright © 2006 John Wiley & Sons, Ltd.