All manipulations were conducted under argon with the strict exclusion of oxygen and water by using Schlenk line and glove box techniques. K{P(SiMe3)2} (KP′′) and LnI2(THF)2 (Ln = Sm, Eu, Yb) were prepared following literature procedures. Diethyl ether and toluene were purged with nitrogen and passed through columns containing alumina catalyst and molecular sieves and pyridine was dried over CaH2 before being degassed, refilled with argon and stored over 4 Å molecular sieves (pyridine) or stored over a potassium mirror before use (diethyl ether, toluene). Hexane was dried by refluxing over potassium and stored over a potassium mirror, then degassed before use. 18-crown-6 was dissolved in DCM and dried over 4 Å molecular sieves before being filtered and the removal of solvent in vacuo. For NMR spectroscopy, C6D6 was dried by refluxing over K, and was vacuum transferred and degassed by three freeze-pump-thaw cycles before use. NMR spectra were recorded on a Bruker AVIII HD 400 spectrometer operating at 400.07