We have reported a general and straightforward synthesis scheme for high-yield preparation of single-crystals of the oxidation-sensitive compounds 1(U-Pu), while a micro-synthesis approach was used for 1(Cf) owing to the scarcity and hard gamma emission of 249Cf. These compounds, in particular 1(U), may serve as alternative precursors to the well-established UI3(thf)4 and the recently introduced UI3 and U(CF3SO3)3.[ , ,12] In addition, we find that for similar An3+/Ln3+ ionic radii the [An(H2O)9]3+ and [Ln(H2O)9]3+ cation structures in 1(M) are almost identical. This reflects the electrostatic nature of the An/Ln-O bonds and thus suggests that the local structure of the hydrated ions in solution may also be similar. Finally, the magnetic susceptibilities of 1(U-Am) may be fully reproduced by ligand-field calculations, from which we can derive the 5f electronic level structures. ; JRC.E.5-Nuclear chemistry