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The detectton of NMR spectra of less sertstttve nuclei coupled to protons may be s@ficantly unproved by a two-dimezsional Founer transform technique tnvolvmg a double transfer of pokuzatton. The method IS adequate to obtam natwaI abundance "N spectra m small sample volumes wth a commerctal spectrometer

Since the sign of V(P,F) in these metal complexes can be assumed to be negative52 from the twodimensional correlation experiments (cf. Figure 4b), it follows that V(F,Fe) is positive. Of particular value is the combination of two-dimensional experiments, e.g. ('H,57Fe) and (31,57Fe) for complex 1. In this way, the relative signs of a variety of scalar couplings in quasitrigonal and -tetragonal complexes can be obtained (cf. Chart IV). To the best of our knowledge, the signs (52) Staplin, D. C.;

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Deuterium spin-decoupled by double-quantum transitions in the manner of Meiboom and co-workers, is applied for the first time to solids, opening the way for a new approach to high resolution proton nmr. Using this approach, the first resolved proton nmr spectrum of

The ring reorientation in permethylferrocene has been studied using high resolution solid state 13 c NMR. The constraints which symmetry places upon the number and types of motional parameters which may be determined from the NMR spectrum are discussed. From comparison of the experimental lineshapes in the slow reorientation temperatures range with theoretical models for random rotations and symmetry related jumps, it is concluded that the reorientation occurs as jumps between symmetry related orientations with jumps of 2-n/5 highly favored over 4rr/5. The activation energy derived for the jump process is 13.5 kjoules/mole.

We describe a field-lock/field-sweep system for the use in superconducting magnets. The system is based on a commercially available field mapping unit and a custom designed broad-band 1 H-NMR probe. The NMR signal of a small water sample is used in a feedback loop to set and control the magnetic field to high accuracy. The current instrumental configuration allows field sweeps of ± 0.4 T and a resolution of up to 10 -5 T (0.1 G) and the performance of the system is demonstrated in a high-field electron paramagnetic resonance (EPR) application. The system should also be of utility in other experiments requiring precise and reproducible sweeps of the magnetic field such as DNP, ENDOR or PELDOR.