Here are five complexes, with ox for the bidentate oxalate ion…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
Here are five complexes, with ox for the bidentate oxalate ion.
- trans-
- cis-
- square planar
- mer-
Which of them are optically active, and how many are there?
Need a reminder? The key ideaShow
A complex is chiral when it has no plane of symmetry. Stereoisomers = geometrical isomers + mirror-image pairs. The observed rotation of a mixture is the rotation of the pure (+) form times the excess of one form, divided by 100 percent.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Plan. Test each complex for a plane of symmetry.
(a) Three oxalate rings make a propeller. There is no plane of symmetry. It is chiral.
(b) The four oxygen atoms of the rings lie in one plane, and that plane is a plane of symmetry. Not chiral.
(c) With the two water molecules cis, there is no plane of symmetry. It is chiral.
(d) A square planar complex lies in one plane, which is a plane of symmetry. Not chiral.
(e) The type is never chiral. The mer isomer has a plane of symmetry. Not chiral.
Answer: (a) and (c) are optically active, so complexes.
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