Synthesis and structures of tin(II) and lead(II) 1-aza-allyls; the [N(SiMe3)C(Ph)C(SiMe3)2]- ligand

Article abstract of DOI:10.1016/S0020-1693(97)05788-5

The new lithium 1-aza-allyl Li[N(R)C(Ph)CR₂](THF) (1) (Li(LL″)(THF)) has been prepared in high yield from LiCR₃(THF)₂ and benzonitrile (R=SiMe₃; THF=tetrahydrofuran). From 1 and MCl₂, the stable 1-aza-allyls [M(μ-Cl)(LL″)] (2 (M=Sn); 3 (M=Pb)) and M(LL″)₂ (4 (M=Sn); 5 (M=Pb)) were obtained. Each of the compounds 1-5 was fully characterised by multinuclear NMR spectroscopy (the compounds are fluxional in solution), mass spectrometry and for 3, 4 and 5 single crystal X-ray diffraction. Crystalline 3 is a centrosymmetric dimer having terminal η³-1-aza-allyl ligands with one bridging Cl^- strongly bonding, Pb-Cl=2.609(3) A, and the other much less so, Pb...Cl=3.276(3) A. Crystalline 4 and 5 are mononuclear (η³-1-aza-allyl)metal(II) enamides, M[N(R)C(Ph)CR₂][N(R)C(Ph):CR₂]. Also reported are the synthesis and NMR spectra of PbCl[N(R)C(Bu^t)CHR] (6).