Synthesis and Structure of Silicon-Bridged Boratabenzene Fluorenyl Rare-Earth Metal Complexes

Abstract

A silicon-bridged boratabenzene fluorenyl ligand [Me2Si(C13H8)(C5H4BNEt2)]2– (L2–) was designed and synthesized. By employment of this ligand, two divalent rare-earth metal complexes [Me2Si(C13H8)(C5H4BNEt2)]Ln(THF)2 (Ln = Sm (1), Yb (2)) were obtained from salt metathesis of K2[Me2Si(C13H8)(C5H4BNEt2)] (K2L) with LnI2(THF)2 in THF. Complex 2 undergoes redox reaction with cyclooctatetraene to give a trivalent Yb complex [(C8H8)Yb]2[μ-{Me2Si(C13H8)(C5H4BNEt2)}2] (3), accompanied with oxidative coupling of two fluorenyl groups. A series of chloro-bridged trimeric trivalent rare-earth metal complexes [Li(THF)4]2[{[Me2Si(C13H8)(C5H4BNEt2)]Ln(μ-Cl)Li(THF)3}3(μ-Cl)3(μ3-Cl)2] (Ln = Nd (4), Sm (5), and Gd (6)) were synthesized by reactions of Li2[Me2Si(C13H8)(C5H4BNEt2)] (Li2L) with LnCl3 in THF. Treatment of K2[Me2Si(C13H8)(C5H4BNEt2)] (K2L) with LnI3(THF)n gave the monomeric complexes [Me2Si(C13H8)(C5H4BNEt2)]LnI(THF) (Ln = La (7), Nd (8), Sm (9), and Gd (10)). These iodides were subsequently reacted with K[CH2...