Ion pair definintion in chemistry I read in the journal of organic chemistry:


  A less striking, but nonetheless significant, attenuation of the reactivity of phenyl selenide anion can be achieved by varying the counterion and/or the relative degree of solvation of the ion pair. For example, when valerolactone (3) is allowed to reflux with sodium phenyl selenide in THF/HMPA for $3\,\mathrm{h}$, one obtains an $85\,\%$ yield of the $\unicode[Times]{x3C9}$-phenylselenenyl carboxylic acid 4.


My question is what is the meaning of the bolded expression (solvation of the ion pair) above?
As already said, ion pair is a pair of two ions like NaCl. When the pair separates completely into its constituent ions in the solvent (like Na+ &amp; Cl- in water), it is called dissociation.

After dissociation, if the solvent associates itself and surrounds the ions like this-


(Sodium ion surrounded by water molecules), it is called Solvation.
Solvation stabilises the compound and makes it either more reactive or less reactive.