| Abstract
| - Hydrogenolysis of the low valent group 13 organyl (AlCp*)4 (1, Cp* = C5Me5) under 3 bar H2 pressure in solution gives Al0 in 100% yield. Co-decomposition of [CpCu(PMe3)] (2) and 0.5 equiv of 1 under the same conditions leads to the intermetallic CuAl2 alloy phase. The Cu/Al ratio can be varied freely by adjusting the molar ratio of 1 and 2. By addition of poly(2,6-dimethyl-1,4-phenylene oxide) α-Cu/Al colloids are obtained. Upon exposure to air preferential oxidation of the Al component takes place leading to Al2O3@Cu/Al core−shell type particles.
- In this work, we present a novel soft chemical synthesis to aluminum nanoparticles based on thehydrogenolysis of the metastable organoaluminum (I) compound (AlCp*)4 (1) in mesitylene at 150 °Cand 3 bar H2. Aiming at the development of a general wet-chemical, nonaqueous route to M/E intermetallicnanophases (E = Al, Ga, In), we studied the co-hydrogenolysis of 1 with [CpCu(PMe3)] (2) as the modelcase aiming at Cu/Al alloyed nanoparticles. One equivalent of 1 combined with 2 equiv of 2 yields thenanocrystalline intermetallic θ-CuAl2 phase (Cu0.33Al0.67), as revealed by elemental analysis, powder X-raydiffraction, transmission electron microscopy (TEM), and energy-dispersive X-ray analysis. The obtainedCu0.33Al0.67 material was also characterized by the 27Al Knight Shift resonance. Alloy particles Cu1-xAlx(0.10 ≤ x ≤ 0.50), typically 15 ± 5 nm (TEM) in size, are accessible as colloidal solutions by variationof the molar ratio of 1 and 2 and by the addition of poly(2,6-dimethyl-1,4-phenylene oxide) duringhydrogenolysis. The 27Al NMR Knight Shift resonance moves to high field starting form the value of1639 ppm for pure nano-aluminum particles to 1486 ppm of Cu0.33Al0.67, reaching 1446 ppm for Cu0.50Al0.50,and was not detectable for Al contents below 50%. Upon oxidation (controlled exposure to the ambient),a selective oxidation of the Al component, presumably forming core−shell structured Al2O3@Cu1-yAly(0.10 ≤ y ≤ 0.50) particles, was studied by UV−vis spectroscopy, 27Al magic-angle spinning NMR, andX-ray photoelectron spectroscopy. The Al content can be freely adjusted and lowered down to about 15atom % (Cu0.85Al0.15) without oxidizing the Cu(0) core.
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