Oxidative Addition of Alkyl Iodides to [Sn(NMe2)2]2: In Situ Generation of RSn(NMe2)3 Compounds

Treatment of [Sn(NMe₂)₂]₂ (1) with R–I (where R = Et, ⁱPr, Me₃SiCH₂, F₃CH₂C, and F₃C) yields the monoalkyltin amides (RSn(NMe₂)₃) (3–7) and the stannous iodide/amide dimer [ISn(NMe₂)]₂ (2) as major products. The monoalkyl stannic amides (3–7) are light-sensitive liquids which are sufficiently volatile (<1% residual mass by TGA) for use as ALD/CVD precursors. The oxidative addition of R–I to a Sn(II) center, followed by exchange of a stannic iodide with unreacted 1, is supported by the solid-state structural analysis of crystalline [ⁱPrSn(NMe₂)₂I]₂ (9) and [ISn(NMe₂)]₂ (2). The stannous iodide byproduct (2) is independently synthesized from stoichiometric amounts of SnI₂ and [Sn(NMe₂)₂]₂. Heating solutions of ⁱPrSn(NMe₂)₃ (4) and ⁱPr–I produces nominal quantities (∼10%) or NⁱPrMe₂ and 9; demonstrating RSn(NMe₂)₃ sensitivity toward alkyl iodides via Sn(IV)–NMe₂ bond cleavage. The modified synthesis and light-sensitivity of [Sn(NMe₂)₂]₂ (1) are also discussed. Multinuclear NMR, solid-state structural analysis, and thermogravimetric differential scanning calorimetry (TGA-DSC) experiments are described.