Lithium-tetrahydroaluminat in Ether: eine NMR-Untersuchung / Lithiumtetrahydroaluminate in Ether: an NMR Study

Abstract

Abstract Ether solutions of LiAlH4 have been investigated by 27Al and 7Li magnetic resonance in the concentration range 3.75-0.0075 M. The Al-signal shows a fine structure due to Al-H coupling only at concentrations below 0.15 M. The observed chemical shift 27Al is only slightly concentration dependent. The line width of the 27Al signal, which is inversely proportional to T2*, reaches a minimum value at a concentration where the best resolution of the 27Al quintet is observed. This, however, is not matched by the 7Li line width whose minimum value was found at a somewhat higher concentration. The results are consistent with multiple ion formation at the higher concentrations and with an ion pair at low concentrations.