In HMPA the 0 atom of the ambident anion may well be more accessible than in any other known medium. This is supported by the data shown in Table 11. The O/C ratio does not change as the cation is varied in size from Na+ to NBu*+, nor does a reagent such as tetraglyme have any effect; the smallest cation, Li+, depresses the ratio somewhat. Reutov6 found such a depression with both lithium and sodium with the use
