# Why do dianions (such as malonate) bind cations more strongly than anions?

Why does a dianion (such as malonate) bind cations more strongly than its equivalent anion (acetate)?

Is it simply because of the proximal availability of another $\ce{O-}$ group that can bind to cations? Does the second $\ce{COO-}$ group on malonate distribute charge in a better way that can allow for stronger binding?

Is it simply because of the proximal availability of another $\ce{O-}$ group that can bind to cations ?