NMR spectroscopic study of the adduct formation and reactivity of homoleptic rare earth amides with alkali metal benzyl compounds, and the crystal structures of [Li(TMEDA)2][Nd{N(SiMe3)2}3(CH2Ph)] and [{Li(TMP)}2{Li(Ph)}]2

An NMR spectroscopic study has been conducted into the reactivity of alkali metal benzyls [M(CH2Ph)], (M = Li, Na, K) with lanthanide tris(amide) complexes [Ln(N '')(3)] (Ln = Y, Ce, Nd; N '' = N(SiMe3)(2)) and [Ce(TMP)(3)] (TMP = 2,2,6,6-tetramethylpiperidide). It was found that for [Ln(N '') (3)], benzyl adducts [M] [Ln(N '')(3)(CH2Ph)] were initially formed, and the molecular structure for M = Li(TMEDA)(2) and Ln = Nd was determined revealing a distorted tetrahedral [Nd(N '')(3)(CH2Ph)] anion. In all cases, these adduct complexes were unstable, intramolecularly deprotonating a methyl arm of a N '' ligand via benzyl basicity and eliminating toluene to prepare cyclometallated complexes of the form [M][Ln(N '')(2){k(2)-CH2Si(Me)(2)N(SiMe3)}]. In parallel studies, reactions of [Li(Ph)] with [Ln(N '')(3)] (Ln = Ce, Nd) afforded [Li(N '')], whilst for (Ln = Y) adduct formation was observed. [Ce(TMP)(3)] did not generate any characterisable bimetallic adducts. The reaction of [Li(Ph)] with [Li(TMP)] afforded the hexanuclear [{Li(TMP)}(2){Li(mPh)}](2), which features lithium in three different coordination environments. (C) 2017 Elsevier B.V. All rights reserved.