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I am trying to understand how will acetamide molecules behave in the presence of lithium salts with different anions (nitrate, bromide and perchlorate).

Among the three, it is evident that bromide is the most electronegative, therefore should induce maximum polarisation on acetamide, am I right?

Secondly, what will happen to the atomic partial charge distribution of the acetamide molecule in the presence of these anions (and of course cations)? Will the amide group become more positive and the carbonyl group become more negative?

PS: I am trying to get a crude partial charge distribution (without making quantum calculations) to run molecular dynamics simulations of mixtures of acetamide with these salts.

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  • $\begingroup$ You mean what happens if you dissolve lithium salts in acetamide? Thinking about some vague polarisation does no good here. Li coordinates to carbonyls, and original ligands, amide groups hydrogen bond with these ligands and carbonyls, and that's still a crude description. $\endgroup$
    – Mithoron
    Oct 28 '21 at 15:39
  • $\begingroup$ Yes, in this case dissolving lithium salts at a particular mole ratio in acetamide makes it a eutectic mixture. I am trying to simulate them. You're right about the fact that lithium coordinates with carbonyl and the anions H-bond with the amide group, but apart from there is also significant charge transfer, which can ideally be obtained from QM calculations, but I am just wondering there is some hand-waving arguments to figure this out. $\endgroup$
    – user35952
    Oct 29 '21 at 5:09
  • $\begingroup$ Anions can be compared based on how weakly coordinating they are. Less coordinating anion makes coordination with carbonyls more preferable. $\endgroup$
    – Mithoron
    Oct 29 '21 at 14:31
  • $\begingroup$ I am sorry, don't the anions coordinate with the amide group in this scenario? $\endgroup$
    – user35952
    Oct 30 '21 at 6:12
  • $\begingroup$ I meant with lithium - amide displaces anions, particularly weakly coordinating, like perchlorate. Anions also hydrogen bond with N-H, but interaction is pretty weak. $\endgroup$
    – Mithoron
    Oct 30 '21 at 13:12

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