A series of heavy lanthanide metallocenium cations [Ln(Cpttt)2]+ (Ln = Y, Gd, Dy, Ho, Er, Tm, Yb, Lu; Cpttt = C5H2tBu3-1,2,4) were recently prepared by halide abstraction of [Ln(Cpttt)2(Cl)], but curiously the Tb analogues remained elusive. Here we report an alternative anion abstraction strategy to access [Tb(Cpttt)2]+, completing the heavy [Ln(Cpttt)2]+ family.