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

The application of one-dimensional dipolar-shift spectroscopy to study the C-13 chemical shielding and the H-1-C-13 dipolar-coupling tensors, and dynamics, on powder samples is demonstrated. The magnitude and the orientation of C-13 chemical shielding and H-1-C-13 dipolar-coupling tensors for the metallocenes of Fe, Mg, and Ru are determined. The H-1-C-13 dipolar-coupling tensor and the orientation of the principal axes of the C-13 chemical-shift tensors in the molecular frame are identical for all the metallocenes while the magnitudes of the C-13 chemical-shift tensors are different. The effect of the motion about the five-fold symmetry axis on these tensors is analyzed. (C) 1999 Elsevier Science B.V. All rights reserved.