Syntheses of organolanthanum and -cerium cations and labile precursors

The lanthanide-iodide compounds Cp{double prime}{sub 2}Ln(I)(NCMe){sub 2} (Ln = La, Ce; Cp{double prime} = 1,3-C{sub 5}H{sub 3}(SiMe{sub 3}){sub 2}) serve as useful precursors for complexes containing the early-lanthanide fragments (Cp{double prime}{sub 2}Ln{sup III}){sup +}. This moiety has been incorporated into compounds in which it binds either neutral or anionic ligands. Among these is the heterobimetallic compound (Cp{double prime}{sub 2}Ce({mu}-{eta}{sup 2}-OC)W(CO)(Cp) ({mu}-{eta}{sup 2}-CO)){sub 2} (3), which is unusual in that the cerium(III) center is wholly nonemissive. This observation is explained on the basis of cerium-to-tungsten excited-state energy transfer, since dissolution in polar solvent (acetonitrile) leads to symmetrically solvated ions, loss of close Ce-W contact, and cerium(III) luminescence. Finally, the ionic compounds (Cp{double prime}{sub 2}Ln(NCMe)(DME))(BPh{sub 4}){center dot}0.5DME (5) have been prepared and the lanthanum analogue (5b) has been structurally characterized.