As silyl-substituted Cp R ligands are more effective at delocalizing electron density away from metal ions over their alkyl-substituted counterparts, non-classical Ln(II) [Ln(Cp R )3] -anions are dominated by examples containing SiMe3 groups, though these still tend to readily decompose above -30 °C. Cyclic voltammetry studies have indicated that the reduction of [La(Cp tt )3] requires a significantly more negative potential than [La(Cp′′)3]. The isolation of Ln(II) complexes with alkyl-substituted Cp R is now allowing the effects of ring substitution on the reactivity of Ln(II) ions to be quantified. Recently, Evans and co-workers reported the synthesis and solid state structures of a series of [Ln(Cp R )3] -anions, [Ln(C5Me4H)3] -(Ln = La, Ce, Pr, Nd, Sm, Gd, Tb, Dy) and [Ln(Cp t )3] -(Ln = La, Ce, Gd, Dy; Cp t = C5H4 t Bu), showing that alkyl-substituted Cp R ligands can stabilize Ln(II) ions sufficiently to give isolable complexes below -30 °C. Given that synthetic routes to [Ln(Cp tt )3] (Ln = La, Ce, Nd, Sm) have been reported previously, we were inspired by the work of Lappert and Evans to target a novel series of trigonal Ln(II) [Ln(Cp tt )3] -anions. Herein, we show that the sterically crowded tris-Cp tt framework is sufficient for the kinetic stabilization of early Ln(II) ions below -30 °C, allowing the isolation and characterization of these complexes. The combination of data obtained indicate that the Ln(II) centers in [Ln(Cp tt )3] -for Ln = La, Ce, Pr and Nd adopt 4f n 5d 1 electron configurations, in common with other [Ln(Cp R )3] -anions for these metals.