7Li Nuclear Electric Quadrupole Interactions in Alkyllithium Compounds

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Abstract
The 7Li magnetic resonance in polycrystalline methyllithium‐d3 and ethyllithium‐d5 was examined at room temperature and at 77°K. The 7Li quadrupole coupling parameters were determined from the quadrupole fine structure of the 7Li magnetic resonance to be | e2qQ/h | = 48 kc/sec and η = 0 for methylithium‐d3 and | e2qQ/h | = 83 kc/sec and η = 0.79 for ethyllithium‐d5. The quadrupole coupling is independent of temperature for ethyllithium‐d5, but the temperature dependence of the coupling is uncertain for methyllithium‐d3 because of the difficulties in observing the resonance at 77°K. At room temperature the 7Li magnetic resonance of ethyllithium‐d5 exhibits a narrow component, 87 cps broad, superimposed upon the broad, quadrupolar split line. This sharp component, which is similar to that observed in isopropyllithium, t‐butyllithium, and neopentyllithium, is not observed at 77°K and is presumably due to motional narrowing. The 7Li resonance of methyllithium‐d3 displayed no sharp component at room temperature, being like allyllithium, propynyllithium, phenyllithium, fluorenyllithium, and alkoxylithium compounds in this respect.