Synthesis. We have previously shown that when Sm II is coordinatively saturated by large crown-ether ligands such as dibenzo-30-crown-10 that the resultant complex is stable in aqueous media for days. This is somewhat surprising because Sm II normally reduces water and forms {Sm III 2O2} oxo-or hydroxo-dimers. From electrochemical measurements it has been affirmed that the stability of Sm II crown-ether complexes is kinetic in origin. This chemistry has been used to guide our synthetic efforts for Cf II because of the similarities between the Sm III to Sm II standard reduction potential (-1.66 V) with that of californium. Given the difficulties in preparing soluble and anhydrous trans-plutonium starting materials, this former observation suggests that a route that is tolerant to a small amount of water might be initially more flexible than strictly moisture and air-free methods.