[arvin_infinity]

Textbook: "Copper-oxygen bonds are longer than the copper-nitrogen bonds, so the shape is strictly described as a distorted octrahedral shape"

Here is my question: Would I be asked to distinguish between octahedral and distorted octahedral?

2)also am I supposed to know which bonds are longer for drawing the complex ions ?
or would I be asked the reason for it?



+rep

[charco]

(Original post by arvin_infinity)
Textbook: "Copper-oxygen bonds are longer than the copper-nitrogen bonds, so the shape is strictly described as a distorted octrahedral shape"

Here is my question: Would I be asked to distinguish between octahedral and distorted octahedral?
+rep

No, for A' level definitely not.

This is called "Jahn Teller" distortion and it most certainly is NOT in A' level syllabuses ...

[arvin_infinity]

(Original post by charco)
No, for A' level definitely not.

This is called "Jahn Teller" distortion and it most certainly is NOT in A' level syllabuses ...

Phew ! thankss
Just looked it up its beyond A-levels doubt they even make an applied/A* question of it..

what about the 2nd question

[thegodofgod]

(Original post by arvin_infinity)
Phew ! thankss
Just looked it up its beyond A-levels doubt they even make an applied/A* question of it..

what about the 2nd question

All I think they may be able to ask is something like 'Give an example of a distorted octahedral complex and an octahedral complex.'

For [Cu(NH₃)₄(H₂O)₂]²⁺, you just need to know that the Cu-O bond length is longer than the Cu-N bond length

[EierVonSatan]

(Original post by thegodofgod)
All I think they may be able to ask is something like 'Give an example of a distorted octahedral complex and an octahedral complex.'

For [Cu(NH₃)₄(H₂O)₂]²⁺, you just need to know that the Cu-O bond length is longer than the Cu-N bond length

I'd probably say that was a bit unreasonable for the exam board to do. The textbook is just mentioning it in passing.

[thegodofgod]

(Original post by EierVonSatan)
I'd probably say that was a bit unreasonable for the exam board to do. The textbook is just mentioning it in passing.

If this is AQA we're talking about, it's not unreasonable at all - AQA are blood hellbent on changing the format of the papers whenever our year group sits a biology or chemistry exam

[illusionz]

(Original post by charco)
No, for A' level definitely not.

This is called "Jahn Teller" distortion and it most certainly is NOT in A' level syllabuses ...

Isn't a Jahn-Teller distortion due to the occupancies of the d orbitals and not the fact that some of the M-L bonds have a different length to others in a complex.

[arvin_infinity]

(Original post by thegodofgod)
All I think they may be able to ask is something like 'Give an example of a distorted octahedral complex and an octahedral complex.'

For [Cu(NH₃)₄(H₂O)₂]²⁺, you just need to know that the Cu-O bond length is longer than the Cu-N bond length

Yh OCR does that too..well occasionally
And think that was the only example mentioned in the textbook!

[danhirons]

(Original post by illusionz)
Isn't a Jahn-Teller distortion due to the occupancies of the d orbitals and not the fact that some of the M-L bonds have a different length to others in a complex.

you get jahn teller distortiations for cr and cu complexes. It is because of the filling of the d orbitals, if you know the octahedral d orbitals are splitting into t2g and eg symmetry. The eg are dz^2 and dx^2 - y^2. In Cr and Cu 2+ complexes, one of the eg orbitals is singly filled i.e. the electron has a sort of choice as to whether to go in the dz^2 or dx^2-y^2 orbital and removes their degeneracy. This leads to a lengthening of either the equatorial or axial bonds, i think generally its an equatorial contraction and axial elongation. So if you filled the dz^2 first, it would lead to a lowering of the orbitals energy, and an elongation of the bonds due to increased electron electron repulsion.

it is 2am and its been a long day so apologies for anything not exactly correct

[illusionz]

(Original post by danhirons)
you get jahn teller distortiations for cr and cu complexes. It is because of the filling of the d orbitals, if you know the octahedral d orbitals are splitting into t2g and eg symmetry. The eg are dz^2 and dx^2 - y^2. In Cr and Cu 2+ complexes, one of the eg orbitals is singly filled i.e. the electron has a sort of choice as to whether to go in the dz^2 or dx^2-y^2 orbital and removes their degeneracy. This leads to a lengthening of either the equatorial or axial bonds, i think generally its an equatorial contraction and axial elongation. So if you filled the dz^2 first, it would lead to a lowering of the orbitals energy, and an elongation of the bonds due to increased electron electron repulsion.

it is 2am and its been a long day so apologies for anything not exactly correct

Yeah I know all that, that's what I understood a JT distortion to be. I was a bit confused because he seemed to imply that a complex with different ligands with different M-L bond lengths was JT distorted which definetely wasn't what I understood it to be!

[danhirons]

(Original post by illusionz)
Yeah I know all that, that's what I understood a JT distortion to be. I was a bit confused because he seemed to imply that a complex with different ligands with different M-L bond lengths was JT distorted which definetely wasn't what I understood it to be!

oh right sorry! :P

yeah, no idea really, never really dealt with an example like that :/

[charco]

(Original post by illusionz)
Yeah I know all that, that's what I understood a JT distortion to be. I was a bit confused because he seemed to imply that a complex with different ligands with different M-L bond lengths was JT distorted which definetely wasn't what I understood it to be!

My intention was not to confuse!

It's true that I didn't read the OP carefully enough and assumed that he/she was asking about distorted octahedral in copper complexes.

In fact, he/she was looking at a much simpler situation.