complexes, [Ln{P(Si i Pr3)2}2(THF)x] (1-Ln; Ln = Sm, Eu, x = 3; Ln = Yb, x = 2). These complexes are characterized by a combination of NMR, EPR, ATR-IR, electronic absorption and emission spectroscopies, elemental analysis, SQUID magnetometry and single crystal Xray diffraction. We find that the data obtained for 1-Ln complement and contrast with those previously reported for related Ln(II) Pʹʹ and {N(Si i Pr3)2} complexes, due to differences in ligand steric requirements and hard and soft acid and base (HSAB) considerations.