The mother liquor, which was found to be composed of 1 along with the corresponding half-sandwich complex [Lu(Cp ttt )(BH 4 ) 2 (THF)], can be conveniently reused in subsequent synthesis batches of 1 to improve the yield. As lutetium is the last member in the 4f series, its ionic radius may explain the increased difficulty in accommodating two bulky Cp ttt ligands around the metal center.