Dilithium diamides [{Li(OC4H8)}(2){C20H12(NR)(2)}] (R=SiMe(3) or CH(2)Bu(t)) derived from R-, S- or R,S-2,2'-diamino-1,1'-binaphthyl derivatives

The dilithium diamides [{Li(thf)}(2){C20H12(NR)(2)}] (R = SiMe(3) 1 or CH(2)Bu(t) 2, thf = tetrahydrofuran) were prepared from R,S-2,2'-diamino-1,1'-binaphthyl, C20H12(NH2)(2), via C20H12[N(H)SiMe(3)](2) or C20H12[NHC(O)Bu(t)](2) and C20H12[N(H)CH(2)Bu(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 Angstrom shorter than Li(1)-N(1), the two groups R cis to one another, and N(1)-C(1) eta(2) 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{C20H12[N(SiMe(3))](2)}] (M = Ge or Sn), obtained by conversion of the stannylene into the crystallographically characterised [{Sn[(NSiMe(3))(2)C20H12](mu-O)}(3)].