The divalent thulium complex [Tm(Cp ttt )2] (1) was obtained by slightly modifying the original procedure by Nief and co-workers, 21 in order to ensure better reproducibility and a higher isolated yield (for details, see the Supporting Information). Crystals of 1 suitable for X-ray diffraction (XRD) studies could be successfully obtained from a concentrated pentane solution of the complex at low temperature (-40 °C). Owing to the very high solubility of 1 in hydrocarbon solvents, only the crystal structure of the less soluble THF adduct was reported in the seminal publication. The molecular structure of 1 in the solid state (Figure ) confirmed the formation of the base-free complex with two independent molecules of 1 in the asymmetric unit, displaying very similar metrical data.