Reactivity of Complexes of 4fn5d1 and 4Fn+1 Ln2+ Ions with Cyclooctatetraene

The Ln(2+) complexes [K(2.2.2-cryptand)] [Cp'3Ln] (Ln = La, Ce, Pr, Nd, Sm, Eu, Dy, Tm, Yb; Cp' = C5H4SiMe3) were reacted with 1,3,5,7-cyclooctatetraene, C8H8, to determine if the reactivity of the complexes of 4f(n+1) ions differed from that of 4f(n)5d(1) ions. Crystallographically characterizable (C8H8)(2-) complexes were obtained only for the larger metals in the lanthanide series, and two types of products were obtained: [K(2.2.2-cryptand)][Cp'(2)Ln(C8H8)] (Ln = La, Ce) and [K(2.2.2-cryptand)] [Ln(C8H8)(2)] (Ln = Ce, Pr, Nd, Sm). The expected co-products of the two-electron reduction of C8H8 by 2 equiv of [K(2.2.2-cryptand)] [Cp'3Ln], namely, the tetrakis(cyclopentadienyl) complexes, [K(2.2.2-cryptand)] [Cp'(4)Ln], were crystallographically characterized for six metals (Ln = Ce, Pr, Nd, Sm, Dy, Tm).