Cuprous Tris(tert-butoxy)siloxy Complexes and Their Thermolytic Conversion to Copper−Silica and Copper Oxide−Silica Nanocomposites

The ( tert- butoxy)siloxy complex [CuOSi(O t Bu) 3 ] 4 ( 1 ) was prepared by silanolysis of [CuO t Bu] 4 with ( t BuO) 3 SiOH and examined as a single-source precursor to Cu/SiO 2 and Cu n O/SiO 2 ( n = 1, 2) materials. The related complex {Cu[μ-OSiPh(O t Bu) 2 ]} 4 ( 4 ), obtained similarly, was characterized by X-ray crystallography as having a planar Cu 4 O 4 core with oxygen-bridged Cu atoms. The highly associated, sublimable {NaCu[OSi(O t Bu) 3 ] 2 } 6 ( 3 ) was obtained by the addition of NaOSi(O t Bu) 3 to 1 or by reaction of 2 equiv of NaOSi(O t Bu) 3 with CuCl. Thermogravimetric analysis (TGA) of 1 under both oxygen and argon reveals rather sharp, low-temperature conversions to the final ceramic compositions (onset temperatures: ca. 100 °C under oxygen; ca. 150 °C under argon). Under argon, the resulting material consists of Cu 0 and Cu 2 O nanoparticles dispersed in silica, whereas an oxygen atmosphere leads to CuO nanoparticles in silica. These materials are carbon- and hydrogen-free and are produced by elimination of isobutene, tert- butyl alcohol, water, and silanol. The pyrolytic conversion of compound 4 occurs at higher temperature and more gradually but gives relatively clean conversion to a CuO/SiO 2 composite under an oxygen atmosphere. The volatility of 1 allows its use in CVD preparations of thin films. Amorphous thin films with a Cu/Si ratio of 1:0.85 (microprobe analysis) and thicknesses ranging from 200 nm to 6 μm have been obtained.