The electronic structures of 1-Sm and 1-Eu were investigated by CASSCF-SO calculations using the OpenMolcas package (see Supporting Information Table and S7 and Figures and). There is a mixed ground state for The crystal data for [Ln{P(Si i Pr3)2}2(THF)x] (1-Ln; Ln = Sm, Eu, x = 3; Ln = Yb, x = 2) and [Na{P(Si i Pr3)2}(DME)2] are compiled in Tables and. Crystals were examined using a Rigaku XtalLAB AFC11 diffractometer equipped with a CCD area detector and graphite-monochromated Cu Kα (λ = 1.54178 Å) or Mo Kα radiation (λ = 0.71073 Å). Intensities were integrated from data recorded on 1° frames by ω rotation. Cell parameters were refined from the observed positions of all strong reflections in each data set. A Gaussian grid face-indexed correction was used to account for X-ray absorption. The structures were solved using SHELXS. Datasets were refined by fullmatrix least-squares on all unique F 2 values, with anisotropic displacement parameters for all nonhydrogen atoms, and with constrained riding hydrogen geometries; Uiso(H) was set at 1.2 (1.5 for methyl groups) times Ueq of the parent atom. The largest features in final difference syntheses were close to heavy atoms and were of no chemical significance. CrysAlisPro 62 was used for control and integration, and SHELX was employed through OLEX2 for structure solution and refinement.