One-pot synthesis of lithium alkylzinc alkoxo heterocubanes with a LiZn3O4 core as suitable organometallic precursors for Li-containing ZnO nanocrystals

Abstract

A convenient and efficient synthesis of the stable monolithium alkylzinc alkoxo cubanes {Li(thf)(RZn)₃(OR′)₄} [R = Me, R′ = ⁱPr (1), ^tBu (2); R = Et, R′ = ⁱPr (3), ^tBu (4)] is reported. They are well soluble in organic solvents and suitable molecular precursors for the formation of Li-containing ZnO nanoparticles. The compounds are accessible by a convenient one-pot reaction of the respective dialkylzinc with lithium alkoxides in the presence of water and can be isolated as white solids in 35–50% yield. Higher yields (80–85%) for 1 and 3 can be achieved by applying excess ⁱPrOH instead of H₂O as protolysis source. The compounds 1–4 were characterized by elemental analyses, multinuclear NMR and FT-IR spectroscopy, and single-crystal X-ray diffraction analysis (1 and 2). Interestingly, thermal treatment of solutions of 1 and 2, respectively, in anhydrous benzyl alkohol at 190 °C yields pure and highly crystalline Li-containing ZnO nanoparticles as evidenced by powder X-ray diffraction analysis (PXRD), Transition Electron Microscopy (TEM), FT-IR and ⁷Li MAS NMR spectroscopy.