Solid-state 45Sc NMR studies of Cp*2Sc-X and Cp*2ScX(THF)

Cp*Sc-2-X, where X is a halide, were synthesized and studied by solid-state Sc-45 NMR to determine how the Sc-X bond affects quadrupolar NMR parameters. The experimental quadrupolar coupling constants (C-Q) show that the fluoride has the largest coupling constant and that the iodide has the smallest coupling constant. DFT analysis of this data indicates that the C-Q of these compounds is related to core scandium and halide orbitals, which is related to polarizability of the halide and the Sc-X distance. Cp*2ScX(THF) were also investigated by solid-state Sc-45 NMR spectroscopy, and have much smaller C-Q values than the base-free halides. This is related to the change in structure of the THF adduct and occupation of orbitals of -symmetry that reduce C-Q.