Carbon-13 chemical shifts and ~1H-~(13)C dipolar couplings in metal sandwich solids using one-dimensional solid-state NMR spectroscopy

摘要

The application of one-dimensional dipolar-shift spectroscopy to study the ~(13)C chemical shielding and the ~1H-~(13)C dipolar-coupling tensors, and dynamics, on powder samples is demonstrated. The magnitude and the orientation of ~(13)C chemical shielding and ~1H-~(13)C dipolar-coupling tensors for the metallocenes of Fe, Mg, and Ru are determined. The ~1H-~(13)C dipolar-coupling tensor and the orientation of the principal axes of the ~(13)C chemical-shift tensors in the molecular frame are identical for all the metallocenes while the magnitudes of the ~(13)C chemical-shift tensors are different. The effect of the motion about the five-fold symmetry axis on these tensors is analyzed.