Halobenzene adducts of the [Dy(Cp ttt )(Cp*)] + cation have provided an opportunity to quantify the impact of weak transverse interactions on the SMM properties of dysprosocenium complexes. At high temperatures, coordination of haloarenes results in accelerated Orbach relaxation rates, with smaller halides providing a larger transverse crystal field. We additionally find Raman rates to correlate with the number of coordinated halogen atoms. The bromobenzene, o-difluorobenzene and yttrium-doped fluorobenzene adducts show increased QTM rates compared to the parent solvent-free complexes, once accounting for the dilution.