PREPARATION AND CHARACTERIZATION OF LIMGH3, LIMG2H5, LIMGRH2, LIMGR2H, AND LIMG2H3R2 COMPOUNDS

When LiAlH4 in diethyl ether solution was added to LiMgPh3 in diethyl ether, a mixture of Li3AlH6 and MgH2 in a 1:2 ratio was formed. However when the mode of addition was reversed (LiMgPh3 added to LiAlH6), LiMgH3 was formed instead. It was also possible to prepare LiMgH3 by the reaction of LiAlH4 with ate complexes of the type LiMgH2R and LiMgHR2 (where R=Me, Et, or Bu). The ate complexes, LiMgHnR3-n (where n=1 and 2), were prepared as THF-soluble products by the reactions of alkyllithium compounds with alkylmagnesium hydrides or magnesium hydride. When n-butyllithium was allowed to react with MgH2 in a 1:2 molar ratio, LiMg2H5 formed (as an insoluble solid) and was characterized by elemental analyses, infrared and NMR spectroscopy, DTA-TGA, and x-ray powder diffraction analysis. The ebullioscopic molecular weight studies of LiMgR2H compounds (where R=Me and Et) showed them to be dimeric in refluxing THF. © 1978, American Chemical Society. All rights reserved.