Thiocyanate, tetraalkylammonium

Table 3.5-1 lists the E-r values for the allcylammonium thiocyanates and nitrates and the substituted imidazolium salts. It can be seen that the values are dominated by the nature of the cation. For instance, values for monoallcylammonium nitrates and thiocyanates are ca. 0.95-1.01, whereas the two tetraalkylammonium salts have values of ca. 0.42-0.46. The substituted imidazolium salts lie between these two extremes, with those with a proton at the 2-position of the ring having higher values than those with this position methylated. This is entirely consistent with the expected hydrogen bond donor properties of these cations. 

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