Synthesis and structures of crystalline Li, Al and Sn(ii) 1-azaallyls and β-diketiminates derived from [Li{μ,η3-N(SiMe3)C(Ad)C(H)SiMe3}]2 (Ad = 1-adamantyl)

Abstract

The crystalline dimeric 1-azaallyllithium complex [Li{μ,η³-N(SiMe₃)C(Ad)C(H)SiMe₃}]₂ (1) was prepared from equivalent portions of Li[CH(SiMe₃)₂] and 1-cyanoadamantane (AdCN). Complex 1 was used as precursor to each of the crystalline complexes 2–8 which were obtained in good yield. By 1-azaallyl ligand transfer, 1 afforded (i) [Al{η³-N(SiMe₃)C(Ad)C(H)SiMe₃}{κ¹-N(SiMe₃)C(Ad)C(H)SiMe₃-E}Me] (5) with [AlCl₂Me]₂, (ii) [Sn{η³-N(SiMe₃)C(Ad)C(H)SiMe₃}₂] (7) with Sn[N(SiMe₃)₂]₂, and (iii) [Li(N{C(Ad)C(H)SiMe₃-E}{Si(NN)SiMe₃})(thf)₂] (8) with the silylene Si[(NCH₂Bu^t)₂C₆H₄-1,2] [= Si(NN)]. By insertion into the CN bond of the appropriate cyanoarene RCN, 1 gave the β-diketiminate [Li{μ-N(SiMe₃)C(Ad)C(H)C(R)NSiMe₃}]₂ [R = Ph (2), C₆H₄Me-4 (3)], and 5 yielded [Al{κ²-N(SiMe₃)C(Ad)C(H)C(Ph)NSiMe₃}{κ¹-N(SiMe₃)C(Ad)C(H)SiMe₃-E}Me] (6). The β-diketiminate [Al{κ²-N(SiMe₃)C(Ad)C(H)C(Ph)NSiMe₃}Me₂] (4) was prepared from 2 and [AlClMe₂]₂. The X-ray structures of 1 and 3–8 are presented. Multinuclear NMR spectra in C₆D₆ or C₆D₅CD₃ have been recorded for each of 1–8; such data on 8 revealed that in solution two minor isomers were also present.