Synthesis and characterization of the unstable primary amido tin(ii) dimer Sn2{N(H)Dipp}4 (Dipp = C6H3-2,6-Pri2) and the first sesqui-amido hemi-chloride derivative Sn2{N(H)Dipp}3Cl: facile conversion of a primary amide to the imide (SnNDipp)4

Abstract

The primary tin(II) amido derivatives Sn₂{N(H)Dipp}₄ (1) and Sn₂{N(H)Dipp}₃Cl (2) (Dipp = C₆H₃-2,6-Prⁱ₂) have been prepared and characterized. Compound 1 was obtained by the transamination of Sn{N(SiMe₃)₂}₂ with H₂NDipp in a 1 : 2 ratio or by the reaction of two equivalents of LiN(H)Dipp with SnCl₂. The attempted preparation of Sn(Cl){N(H)Dipp} by reaction of LiN(H)Dipp with SnCl₂ in a 1 : 1 ratio led to the isolation of the unique species Sn₂{N(H)Dipp}₃Cl, which is the first example of a sesqui-amido derivative of a group 14 element. Both 1 and 2 were characterized by ¹H and ¹¹⁹Sn NMR spectroscopy, X-ray crystallography and Mössbauer spectroscopy. The structures of 1 and 2 feature two tin centers bridged by –N(H)Dipp ligands with the terminal positions being occupied by two N(H)Dipp (1) or –N(H)Dipp and –Cl (2) groups. The compound 1 was found to be unstable under ambient conditions and spontaneously converts to the imide tetramer (SnNDipp)₄ in solution over several days at room temperature, representing a new synthetic route to group 14 element imides.