Synthesis and Reactivity of Mono(pentamethylcyclopentadienyl) Tetraphenylborate Lanthanide Complexes of Ytterbium and Samarium: Tris(ring) Precursors to (C5Me5)Ln Moieties

Abstract

The synthesis of unsolvated (C5Me5)Ln(BPh4) complexes (Ln = Sm, Yb) has been investigated to determine if the productive chemistry of the metallocene tetraphenylborate complexes, (C5Me5)2Ln(μ-Ph)2BPh2, can be expanded to mono(pentamethylcyclopentadienyl) systems. Precursors (C5Me5)2Yb, 1, and (C5Me5)2Sm, 2, were both prepared by desolvation of (C5Me5)2Ln(THF)2 under high vacuum in near quantitative yields. Compounds 1 and 2 react with [Et3NH][BPh4] to form divalent (C5Me5)Ln(μ-η6:η1-Ph)2BPh2 (3, Yb; 4, Sm) complexes in which two of the phenyl rings of the tetraphenylborate counteranion coordinate η6 to the lanthanide to generate a three-ring coordination geometry involving cyclopentadienyl and arene coordination. In contrast to the expected trigonal plane defined by the three-ring centroids in 3, the structure of 4 is pyramidal with Sm 0.41 A out of the plane of the three-ring centroids. Complex 3 reacts with THF to make the polysolvated complex, [(C5Me5)Yb(THF)4][BPh4], 5, which can also be obtained from...