I don't understand why Iodine is a good nucleophile or lewis base but a poor bronsted lowry base? If it is good enough to share electrons with other atoms as a nucleophile, why does it not with hydrogen?
Iodine - Good lewis base but poor bronsted lowry base
- Thread starter DingDongD
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The definition of a Brønsted-Lowry base is dependent on the finalized strength of the bond between hydrogen and the atom in question (which in this case is iodine). In comparison to other atoms such as fluorine, you can observe via periodic trends that iodine has a large radius. This in turn results in a weaker bond created by hydrogen and iodine and thus is not as willing to accept a hydrogen compared to F. Thus iodine is a poor Brønsted-Lowry base relative to it's neighboring atoms due to it's larger size and weaker hydrogen bond strength.
Thank you. I think I can understand a bit better now. So, or nucleophiles, the strength of the finalized strength of the bond isn't really taken into consideration, just the fact that it can donate electrons. However, that isn't generally the case with BL bases, as you were saying.
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Exactly, when you look at an atom from the perspective of a BL base your assessing it's ability to accept a hydrogen relative to other atoms that accept hydrogens.
When you look at an atom from the perspective of a nucleophile you are now assessing it based on it's leaving group, the total reactivity usually considered by it's ability to donate electrons, and the solvent environment.
