The first chromium-53 solid-state nuclear magnetic resonance spectra of diamagnetic chromium(0) and chromium(VI) compounds

Chromium-53 is a spin-3/2 nucleus with a relatively small magnetic moment, low natural abundance, and large quadrupole moment. These properties have severely hampered the development of Cr-53 NMR, especially in the solid state. In this Communication, the first Cr-53 solid-state NMR spectra of prototypal diamagnetic chromium(0) and chromium(VI) compounds are presented. Specifically, analyses of Cr-53 NMR spectra of solid hexacarbonylchromium(0),caesium chromate(VI), and potassium chromate(VI) have allowed for the determination of Cr-53 quadrupolar coupling parameters and the rrst chromium chemical shift (CS) tensors. This work demonstrates the potential of Cr-53 solid-state NMR, in particular the extreme sensitivity of the Cr-53 quadrupolar coupling constant to the local chromium environment. Comparisons are made to known Cr-53 NMR parameters available from solution studies, and to the Mo-95 solid-state NMR parameters of analogous molybdenum compounds. The influence of crystal symmetry present in isomorphic Cr(CO)(6) and Mo(CO)(6) is strongly reflected in the magnitudes of the metal nuclei CS tensors and in their orientation with respect to their corresponding electric field gradient tensors.