Crystal Field Theory: Tetrahedral Complexes - Video Tutorials & Practice Problems
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1
concept
The crystal field splitting pattern for tetrahedral complexes has the d orbitals in between the axes as having the higher energy.
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Now recall in tetrahedral complexes that the liga orbital interactions, the in between the axes are the strongest. And if we're talking about our five D orbitals, the ones that lie in between the axes are dxydyz and DXZ, remember the interaction there is the highest, therefore, they should have the highest energy. So when we segregate these different types of orbitals from one another to create our crystal field diagram here, we place the three of them up top here. So here we have dxydyz and DXZ. There are three of them and remember three here at Stanford triplet. So that's why it's tub two set for these three DX squared minus Y squared and DZ squared. These are the orbitals that lie along or on the axes, they have less interaction and therefore, they would have less energy. That's where they're down here. And there's a pair of them, two of them. And we use a notation of E. So they would represent our E set the difference in energy between these orbitals is delta, our crystal field splitting energy. And in fact, tetrahedral complexes have the smallest delta. So keep that in mind as we talk about different complexes in, in relation to tetrahedral octahedral and square planar complexes. Out of those three tetrahedral complexes have the smallest delta.
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example
Example
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Which one of the following complexes will have the smallest energy gap between the E set and the T two set of orbitals. So our energy gap here, they're just talking about delta, which is our crystal field energy here splitting energy. And they want the smallest one that happens with tetrahedral complexes to be a tetrahedral complex. You need to have a metal cion connected to four ligands or have a metal connected to four ligands. If we take a look here, the only one that has a metal connected to four ligands is option D in it, we have copper two plus connected to four bromide ions. The other ones don't work because in the first one, we have six ligands. So that would be octahedral, we have ox three is not, we don't even need to worry about. Um if it's mono dentate, bent poly dentate three, here we need four ligands. EDT A here we're only showing one but EDT A remember is a poly dentate ligand. So it has six donor atoms. The only one that fits the great description of having four ligands or four donor atoms is option D. This one will result in the smallest energy gap.
3
Problem
Problem
For which of the following complexes, the energies of the dx2−y2 and dz2 orbitals will be lower than the other three d orbitals?
A
[Co(en)3]3+
B
[Ni(CN)4]2–
C
[Zn(H2O)4]2+
D
[AuCl2]–
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