Hydrolysis of organometallic and metal–amide precursors: synthesis routes to oxo-bridged heterometallic complexes, metal-oxo clusters and metal oxide nanoparticles

Abstract

The hydrolysis reaction between Brønsted basic organometallic or metal-amide reagents with Brønsted acidic OH groups from water or metal-hydroxides may act as a controlled stoichiometric strategy for the formation of M-O-M bonds, if careful consideration of reaction conditions is employed. This article explores the utilisation of highly reactive organometallic and metal-amide complexes from across the periodic table as reagents for the synthesis of metal-oxo clusters, oxo-bridged heterobimetallics and metal oxide nanoparticles. Such reactivity typically occurs at low temperatures with the release of hydrocarbon or amine by-products. The impact of ligand coordination, M-C bond strength, M-OH acidity and reaction temperature are discussed.

The use of mixed-metal single source precursors for the synthesis of complex metal oxides

“…Structures based on simple adducts of mono-metallic components can be susceptible to segregation, and thus a more robust strategy may be used to build a covalent bridge between metals. Oxo bridged M−O−M' structures can be prepared by the reaction of (basic) organometallic complexes with (acidic) metal hydroxides, 82 Solvothermal mechanisms introducing metal oxo or metal hydroxide functionalities (O shown in red) leading ultimately to the condensation of a metal oxide. Please do not adjust margins Please do not adjust margins likewise organometallic reagents can react with pendant acidic OH groups on multidentate ligands.…”

Cu/M:ZnO (M = Mg, Al, Cu) colloidal nanocatalysts for the solution hydrogenation of carbon dioxide to methanol

“…1,2 Zinc oxide, a wide band-gap (3.3 eV), n-type semiconductor, is an important material in both contexts, providing useful properties such as transparency and accessible redox chemistry, while using only abundant elements. [3][4][5][6][7] Consequently, ZnO nanoparticles (NPs) have found use as solution-processible electronic inks, and as high surface area catalysts. [8][9][10] Relevant to this work are elegant examples of property enhancement through heterovalent substitutional doping of ZnO.…”

“…to prevent phase separation. 1,4 n-Type ZnO doping is more easily achieved and is most often accomplished through incorporation of Group 13 elements at interstitial sites. 3 For instance, aluminium doping enhanced the optical and electronic properties of ZnO, affording a cheaper and less toxic competitor to the ubiquitous transparent conducting oxide, indium tin oxide (ITO).…”

“…9,44,58 Hydrolytic syntheses provide straightforward control of ligand coverage and kinetic control over the growth of particles, allowing access to small ZnO nanoparticles (2-4 nm). 4,50,54,57 The methodology is potentially attractive for dopant incorporation since a second organometallic reagent can simply be added to the one-pot hydrolysis reaction. The synthesis of doped-ZnO nanoparticles via co-precipitation methods has allowed doping levels >10% (e.g.…”

“…Group 1, 15,17 Group 2, 14 Group 13, 28,29 and Group11 16,[59][60][61] ); however, there are only a few examples of successful doping using organometallic routes. 4,62,63 Chaudret and co-workers demonstrated that the addition of Li-amides during the hydrolysis of ZnCy2, in the presence of octylamine, led to the formation of spherical Li-doped-ZnO nanoparticles (2.4-4.3 nm, Li content 1-10 mol %). The nanoparticle growth was controlled by the localisation of LiOH on the surface of ZnO.…”