HardChemistryHigh School (11–12)Coordination Compounds › Isomerism in Coordination CompoundsNumerical
The glycinate ion bonds to a metal through its nitrogen and through one oxygen…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
The glycinate ion bonds to a metal through its nitrogen and through one oxygen. It is an unsymmetrical bidentate ligand, written here as N-O. The octahedral complex holds three of them. Find the number of geometrical isomers and the number of stereoisomers.
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. Find the geometrical isomers first. Then ask which have mirror images.
Step 1. Geometrical isomers. The three nitrogen atoms either sit at the corners of one face (fac) or lie in one plane through cobalt (mer). That gives geometrical isomers.
Step 2. Mirror images. Neither isomer has a plane of symmetry, because the rings spiral like propeller blades and the ligands are unsymmetrical. Each of the two exists as two enantiomers.
Step 3. Total. stereoisomers.
Check. Geometrical isomers plus mirror-image pairs: .
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