Inorganic Grignard Reagents. Preparation and Their Application for the Synthesis of Highly Active Metals, Intermetallics, and Alloys

• Published in: Chemistry of materials 1995-06, Vol.7 (6), p.1153-1170
• Main Authors: Aleandri, Lorraine E, Bogdanovic, Borislav, Bons, Peter, Duerr, Christine, Gaidies, Andre, Hartwig, Thomas, Huckett, Sara C, Lagarden, Martin, Wilczok, Ursula, Brand, Richard A
• Format: Article
• Language: English
• Subjects: Chemistry; Colloidal state and disperse state; Exact sciences and technology; General and physical chemistry; Powders
• ISSN: 0897-4756; 1520-5002
• DOI: 10.1021/cm00054a015

NiCl sub 2 , FeCl sub 2 , PdCl sub 2 , PtCl sub 2 , RuCl sub 3 , RhCl sub 3 , and IrCl sub 3 react with excess amounts of active magnesium: (Mg exp * ) or diethylmagnesium (Et sub 2 MG) in THF generating soluble bimetallic species with the generalized formula [M sub 1 (MgCl) sub m mult(MgCl sub 2 ) sub p ], m=1-3, p=0-1 ("inorganic Grignard reagents"). In the Ru- and Ir-Mg-Cl systems, it appears that two different metal Grignard reagents, [Ru(MgCl) sub 2 mult0.5MgCl sub 2 ] (8a) or [IrMgClmultMgCl sub 2 ] (10a) and [M'(MgCl) sub 3 ], M'=Ru (8b) or Ir (10b), can be prepared through application of Et sub 2 Mg and Mg exp * respectively. Hydrolysis or alcoholysis of THF solutions containing the inorganic Grignard reagents deliver finely divided, x-ray amorphous metals M exp 1 (usually) hydrogen gas and the corresponding Mg salts. The inorganic Grignard reagents in THF react with metal chlorides M sub 2 Cl sub n in the molar ratio of n:m with the precipitation of nanoparticulate intermetallics or alloys M exp 1 sub n M sub m exp 2 according to equation n[m exp 1 (MgCl) sub m mult(MgCl sub 2 ) sub p ] + mM exp 2 Cl sub n - > M exp 1 sub n M exp 2 sub m DN + (mn+p)MgCl sub 2 . The isolated x-ray amorphous intermetallics or alloys were characterized by exp 57 Fe Mossbauer spectroscopy (where M exp 2 =Fe), DSC and high resolution TEM. Thermal annealing of the x-ray amorphous bimetallic solids leads in most cases to micro- or nanocrystalline intermetallics or alloys which can then be identified through x-ray powder diffraction. Thus the preparation of highly active, nanocrystalline metals, intermetallics, and alloys is possible through solution chemistry via a controlled two-step process.