The β-Agostic Structure in (C Me ) Sc(CH CH ): Solid-State NMR Studies of (C Me ) Sc-R (R=Me, Ph, Et).

Multinuclear solid-state NMR studies of Cp* Sc-R (Cp*=pentamethylcyclopentadienyl; R=Me, Ph, Et) and DFT calculations show that the Sc-Et complex contains a β-CH agostic interaction. The static central transition Sc NMR spectra show that the quadrupolar coupling constants (C ) follow the trend of Ph≈Me>Et, indicating that the Sc-R bond is different in Cp* Sc-Et compared to the methyl and phenyl complexes. Analysis of the chemical shift tensor (CST) shows that the deshielding experienced by Cβ in Sc-CH CH is related to coupling between the filled σ orbital and the vacant πSc⋯HC* orbital.