STEREOCHEMISTRY OF POLYNUCLEAR COMPOUNDS OF MAIN GROUP ELEMENTS .7. STRUCTURE OF OCTAMETHYLDIALUMINUMMONOMAGNESIUM

Dimethylmagnesium dissolves in trimethylaluminum to give two crystalline compounds with melting points of 39 and 54°. The crystal structure of the lower melting electron-deficient product octamethyldialuminum-monomagnesium, Mg[Al(CH3)4]2, has been determined by three-dimensional, single-crystal X-ray diffraction techniques. The compound crystallizes in the triclinic space group [formula-omitted], with two molecules per unit cell. The cell parameters are a = 6.955, b = 10.802, and c = 10.287 Å and x = 102.35, β = 105.03, and γ = 92.49°. The average magnesium-carbon(bridge)-aluminum angle is 77.7°, and the average magnesium-aluminum distance, 2.704 Å. The conventional discrepancy index for the structure is 7.2%. Nuclear magnetic resonance studies on the trimethylaluminum-dimethylmagnesium and trimethylaluminum-dimethylberyllium systems are reported. In the latter, low-temperature spectra are interpreted in terms of the formation of a complex with the empirical formula Be[A1](CH3)4]2. © 1969, American Chemical Society. All rights reserved.