Fairly simple this one: just a few definitions for you.
A mononucleating ligand can only bind to one transition metal at the same time. This could be because:
- There’s only one pair of lone electrons to use for bonding on the ligand. That’s pretty much your vanilla ligands, like pyridine, ammonia, etc.
- There’s more than one pair of lone electrons, but they point to the same binding site. We call this a convergent set of lone pairs. The lone pairs can still only bind to one metal at once, so it’s a mononucleating ligand. 1,2-diaminoethane is a nice example of this, so is 2,2’,6’,2”-terpyridyl… you can see that the lone pairs that the nitrogens have all point to the same site:
A *polynucleating* ligand can potentially bind to more than one transition metal at the same time. This is because:
- There’s more than one lone pair available to bind.
- The lone pairs need to be divergent ie they point to two different spots.
Note: single atoms can be polynucleating ligands if they fufil this criteria. So chloride is a nice example here, along with phenoxide as they potentially can have a metal on either side of the ligand.
What’s the importance of this: ligands and transition metals turn into *lego*. We can make infinite chains, rings, cubes, grids and loads of other interesting stuff. Have a picture of one for now:
People can use me for storing gas, like hydrogen in a fuel cell… *strokes chin*
