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.