Appositive or what?

Bidentate (also called didentate) ligands bind with two atoms, an example being ethylenediamine.

http://en.wikipedia.org/wiki/Denticity

Is "an example being ethylenediamine" a inappropriate appositive?

As far as i know, appositive is usually to define the preceding noun.

My youngest sister, Meghan, will be visiting soon.
"Meghan" is an appositive describing the preceding noun(sister).

So, is the sentence in the beginning exemplifying a different grammar structure than appositive?

thanks