17.29

[Alysia Garcia 1B]

For this problem, we are supposed to find the oxidation number for coordination compound. The solution for part a shows that each ligand has a negative 1 charge but how would you find that? I tried to draw it out and I drew C bonded to N with a triple bond, with C also bonded to Fe and N with a lone pair and I thought that would give a charge of 0.

[AnthonyDis1A]

When determining the charge of the central atom, I think you have to consider the ligands as separate molecules. For the CN ligand, you would have to draw its Lewis structure under the assumption that it was not bonded with Fe, and that it had a full octet. So you would get CN-.

[jadam_1E]

A good way to think when calculating oxidation number for a complex is to consider all the bonding between the central metal atom and the ligands to be 100% ionic, so when finding the charge on a ligand, consider the ligand separate. For 12.29, this would mean considering each CN- to have a charge of -1.