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

Abstract

Cp*₂Sc–X, where X is a halide, were synthesized and studied by solid-state ⁴⁵Sc 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 ⁴⁵Sc 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 π-symmetry that reduce C_Q.