[Catsceo]

Simple question here (I hope) but are hydroxide ions in aqueous solution present as hydroxide or bihydroxide (H3O2-)?  Or something else?  The reason I ask is because hydronium is present as Zundel and Eigen cations in aqueous solution (and a few others from what I read on wikipedia).  I think it would due to the fact fluorine forms the bifluoride ion, and oxygen's similar, albeit less, electronegativity to fluorine.  The wikipedia article on hydroxide mentions H3O2- but doesn't say wether its present in aqueous solution.  Can anyone fill in the gap for me?

[Borek]

I doubt there is a single entity that exists in the solution - what will be present will be a whole family of ions (something like (H₂O)_nOH^-), in a dynamic equilibrium.