Ultrahigh-Resolution Homo- and Heterodecoupled 1H and TOCSY NMR Experiments.

Abstract

The original homonuclear decoupled (pure shift) experiments provide ultrahigh-resolution 1H spectra of compounds containing NMR-active heteronuclei of low natural isotopic abundance (e.g., 13C or 15N). In contrast, molecules containing highly abundant heteronuclei (like 31P or 19F) give doublets or a multiple of doublets in their homonuclear decoupled spectra, depending on the number of heteronuclear coupling partners and the magnitude of the respective coupling constants. In these cases, the complex and frequently overlapping signals may hamper the unambiguous assignment of resonances. Here, we present new heteronuclear decoupled (HD) PSYCHE 1H and TOCSY experiments, which result in simplified spectra with significantly increased resolution, allowing the reliable assessment of individual resonances. The utility of the experiments has been demonstrated on a challenging stereoisomeric mixture of a platinum-phosphine complex, where ultrahigh resolution of the obtained HD PSYCHE spectra made the structure elucidation of the chiral products feasible. HD PSYCHE methods can be potentially applied to other important 31P- or 19F-containing compounds in medicinal chemistry and metabolomics.