[Firehchicken]

Hi,

In question 33 the answer is B). I can figure out that Ni2+ has 8 3d electrons. Pairing all 8 electrons in low spin would give 6 paired electrons in t2g and 2 unpaired in eg. So, how do I obtain zero unpaired electrons?

In question 34, the answer is D. Fe2+ has 6 3d electrons. Pairing them in low spin would give 3 electron pairs in t2g, with the eg orbital left empty. So my question is, why is it +2P and not +3P? Surely, there are 3 paired electrons so it should be 3P right?

[mjc123]

33) Are all Ni²⁺ complexes octahedral?
34) What are you comparing this state with? What would be the energy of a spherical, isolated Fe²⁺ ion?

[Firehchicken]

33) Are all Ni²⁺ complexes octahedral?


34) What are you comparing this state with? What would be the energy of a spherical, isolated Fe²⁺ ion?

33)Umm yeah, as far as I have been taught. I havent been taught any other geometries??

34)I'm sorry, I don't quite follow what you're trying to say?

[mjc123]

Have you not been taught that square planar MX₄ geometry is common for d⁸ ions? If not, you probably don't know how the d orbitals split in this geometry. There are no triple degeneracies; you get four sets of orbitals; e_g, a_1g, b_2g, b_1g (in order of increasing energy). How would 8 electrons go into these orbitals?

An isolated ion would have all five 3d orbitals degenerate. How do 6 electrons go into these orbitals? What is the pairing energy?