Synthesis of chelating diamido Sn(iv) compounds from oxidation of Sn(ii) and directly from Sn(iv) precursors

Abstract

Three dimethyltindiamides containing chelating diamide ligands were synthesised from the reaction of the dilithiated diamine and Me₂SnCl₂; [SnMe₂(L₁)] 1 (L₁ = κ²-N(Dipp)C₂H₄N(Dipp)), [SnMe₂(L₂)] 2 (L₂ = κ²-N(Dipp)C₃H₆N(Dipp)) and [SnMe₂(L₃)] 3 (L₃ = κ²-N(Dipp)SiPh₂N(Dipp)), Dipp = 2,6-ⁱPr₂C₆H₃. Reaction of (L₂)H₂ with SnCl₄ and NEt₃ led to the formation of the diamidotin dichloride [SnCl₂(L₂)] 4 whereas reaction of (L₁)H₂ with SnCl₄ and NEt₃, or [Sn(L₁)] with SnCl₄, led to the exclusive formation of the amidotin trichloride [SnCl₃{κ²-DippN(H)C₂H₄N(Dipp)}] 5. Reactions of [Sn(L₁)] with sulfur and selenium formed [{Sn(L₁)(μ-E)}₂] (E = S 10 and Se 11). MeI reacted with N-heterocyclic stannylenes to generate the Sn(IV) addition products [Sn(Me)I(L₁)] 12, [Sn(Me)I(L₂)] 13, [Sn(Me)I(L₃)] 14 and [Sn(Me)I(L₄)] 15 (L₄ = κ³-N(Dipp)C₂H₄OC₂H₄N(Dipp)), and subsequent reaction with AgOTf (OTf = OSO₂CF₃) generated the corresponding Sn(IV) triflates [Sn(Me)OTf(L₁)] 16, [Sn(Me)OTf(L₂)] 17 and [Sn(Me)OTf(L₄)] 19 with [Sn(Me)OTf(L₃)] 18 formed only as a mixture with unidentified by-products. All of the compounds were characterised by single crystal X-ray diffraction.