Reactions of Li- and Yb-coordinated N,N′-bis(trimethylsilyl)-β-diketiminates: one- and two-electron reductions, deprotonation, and C–N bond cleavage

Abstract

The synthesis and characterisation of novel Li and Yb complexes is reported, in which the monoanionic β-diketiminato ligand has been (i) reduced (SET or 2 × SET), (ii) deprotonated, or (iii) C–N bond-cleaved. Reduction of the lithium β-diketiminate Li(L^R,R′) [L^R,R′ = N(SiMe₃)C(R)CHC(R′)N(SiMe₃)] with Li metal gave the dilithium derivative [Li(tmen)(μ-L^R,R′)Li(OEt₂)] (4, R = R′ = Ph; or 5, R = Ph, R′ = Bu^t). When excess of Li was used the dimeric trilithium β-diketiminate [Li₃(L^R,R′)(tmen)]₂ (6, R = R′ = C₆H₄Bu^t-4 = Ar) was obtained. Similar reduction of [Yb(L^R,R′)₂Cl] gave [Yb{(μ-L^R,R′)Li(thf)}₂] (1, R = R′ = Ph; or 2, R = R′ = C₆H₄Ph-4 = Dph). Use of the Yb–naphthalene complex instead of Li in the reaction with [Yb(L^Ph,Ph)₂] led to the polynuclear Yb clusters [Yb₃(L^Ph,Ph)₃(thf)] (3), [Yb₃(L^Ph,Ph)₂(dme)₂] (7), or [Yb₅(L^Ph,Ph)(L¹)(L²)(L³)(thf)₄] (8) [L¹ = N(SiMe₃)C(Ph)CHC(Ph)N(SiMe₂CH₂), L² = NC(Ph)CHC(Ph)H, L³ = N(SiMe₂CH₂)] depending on the reaction conditions and stoichiometry. The structures of the crystalline complexes 4, 6·2½(hexane), 6·5(C₆D₆), 7 and 8 have been determined by X-ray crystallography (1 and 3 have been published).