Dilithium diamides [{Li(OC4H8)}2{C20H12(NR)2}](R = SiMe3 or CH2But) derived from R-, S- or R,S-2,2′-diamino-1,1′-binaphthyl derivatives

Abstract

The dilithium diamides [{Li(thf)}₂{C₂₀H₁₂(NR)₂}](R = SiMe₃1 or CH₂Bu^t2, thf = tetrahydrofuran) were prepared from R,S-2,2′-diamino-1,1′-binaphthyl, C₂₀H₁₂(NH₂)₂, via C₂₀H₁₂[N(H)SiMe₃]₂ or C₂₀H₁₂[NHC(O)Bu^t]₂ and C₂₀H₁₂[N(H)CH₂Bu^t]₂, respectively, and were transformed into SiCl₂[C₂₀H₁₂(NR)₂] by treatment with SiCl₄. The crystal structures of 1 and 2 were determined. They are monomers, having a Li(1)N(1)Li(2)N(2) buckled ring, with Li(1)–N(2)ca. 0.2 Å shorter than Li(1)–N(1), the two groups R cis to one another, and N(1)–C(1)η² bonded to Li(1). The R and S enantiomers were similarly prepared and their optical stability was demonstrated by their hydrolysis to R- and S-C₂₀H₁₂(NH₂)₂, respectively. Evidence is provided for the structures of [M{[graphic omitted](SiMe₃)]₂}](M = Ge or Sn), obtained by conversion of the stannylene into the crystallographically characterised [{Sn[([graphic omitted]₂₀H₁₂](µ-O)}₃].