Measurement of J(H,H) and long-range J(X,H) coupling constants in small molecules. Broadband XLOC and J-HMBC

New methods for the measurement of homonuclear J(H,H) and heteronuclear lon g-range J(C,H) coupling constants are presented. The heteronuclear and homo nuclear coupling constants are measured by schemes based on J-HMBC and XLOC , respectively, and they all employ a low-pass J filter to eliminate one-bo nd J(C,H) responses. The J-HMBC experiments are automatically broadband in their excitation over a range of J(C,H) coupling constants whereas the broa dband feature for XLOC is achieved by employing the approach used in broadb and HMBC. Copyright (C) 2001 John Wiley & Sons, Ltd.