By adapting the literature protocols for the preparation of Ln(II) complexes in tris-Cp′ frameworks, [K(2.2.2-cryptand)][Ln(Cp tt )3] (1-Ln, Ln = La, Ce, Pr, Nd) were synthesized by the reduction of parent [Ln(Cp tt )3] (2-Ln) with KC8 in THF in the presence of 2.2.2-cryptand at -30 °C (Scheme 1); the attempted synthesis of 1-Sm by the same method gave an intractable mixture of products. Synthetic routes to the Ln(III) precursors 2-Ln have been reported previously, Information). Contemporary methods for the preparation of non-classical Ln(II) complexes typically utilize a glove box with a cold well and a pre-cooled KC8 column. 9,10 However, we were keen to use the Schlenk line protocols used by Lappert and co-workers used prior to this work, hence all manipulations for the synthesis of 1-Ln were performed using standard Schlenk techniques, with reaction mixtures, filtrations and recrystallizations performed below -30 °C to prevent thermal decomposition. Crystals of 1-Ln were isolated from mixtures of THF and Et2O layered with hexane; the crystalline yields for 1-La, 1-Ce, 1-Pr and 1-Nd were 20%, 48%, 22% and 28%, respectively.