[BonkersBow]

Iodine anion is generally found to be a better leaving group than bromine in Sn2 (weaker bonding)- is this reversed by switching from non protic to protic solvents, as is the case for the relative nucleophilic strengths of bromine and iodine anions (Iodine anion is a better nucleophile than bromine anion in protic solvents due to poor solvation - the converse being true in acetone). Also Sykes talks about the importance of polarisability in nucleophilicity. Anion size affects both solvation and polarisability, is it possible to determine which of these two is the dominant factor in nucleophilic strength in any reactions?