The reactions of lithium trimethysilylmethyls with isocyanides; structures and reactions of the derived lithium 1-azaallyls, β-diketiminates and a 1-azabuta-1,3-dienyl-3-amide

Abstract

The insertion of ArNC (Ar = 2,6-Me₂C₆H₃) or Bu^tNC into the Li–C bond of [Li{C(H)(R)R′}] (R = SiMe₃, R′ = R or Ph) led to (i) the lithium 1-azaallyls [Li{N(R″)C(R)C(H)R′}(tmen)] (6a R′ = R, R″ = Ar; 6b R′ = Ph, R″ = Ar; 6c R′ = Ph, R″ = Bu^t), (ii) the lithium β-diketiminates [Li{N(Bu^t)C(R)C(H)C(R)NBu^t}][(LiCHR₂)(CNBu^t)] 1, Li{N(Ar)C(R)C(H)C(R)N(Ar)} 2 and [Li{N(Ar)C(R)C(H)C(Ph)N(R)}(tmen)] 7 (from 6a and PhCN), or (iii) the lithium amide [Li{N(Ar)C(R)C[N(Ar)]C(H)Ph}(tmen)] 8. Treatment of the lithium β-diketiminates 1 and 2 with ZrCl₄ yielded the complexes [ZrCl₃{N(Bu^t)C(R)C(H)C(R)NBu^t}] 3 or [Zr{N(Ar)C(R)C(H)C(R)N(Ar)}Cl₂(μ-Cl)₂Li(OEt₂)₂] 4, while reaction of the lithium compounds 2 or 8 with MeOH gave in high yield the conjugate acids of the corresponding anions [HN(Ar)C(R)C(H)C(R)NAr] 5 or [HN(Ar)C(R)C{N(Ar)}C(H)Ph] 9. Each of the compounds 1–9 was fully characterised by multinuclear NMR spectroscopy, mass spectrometry and microanalysis, while X-ray diffraction data are also provided for the complexes 4, 6b and 8.