The UV-vis spectrum of 2 in pentane (Figure ) shows a major absorption band at 435 nm ( = 2800 L•mol -1 •cm -1 ), along with the onset of a strong band below 350 nm. It contrasts with the spectrum of the related neutral [Lu(Cp i Pr5 ) 2 ] complex, which features minimal absorption in the visible In comparison, in the [K(crypt)][LuCp' 3 ] separated ion-pair complex, an intense band was observed at 518 nm and assigned to a metal-to-ligand charge-transfer (MLCT) transition. TDDFT calculations were carried out in n-pentane to obtain the UV-vis spectrum of 2 (Figure ). An absorption band is found around 400 nm, in agreement with the experimental spectrum, and consists of an MLCT excitation from the SOMO (d z 2 ) to the Lu-Cp ttt antibonding orbital.