As you saw in problem 9 we can have species bound to a central metal ion. These

Question

As you saw in problem 9 we can have species bound to a central metal ion. These species are called ligands. In the past we have assumed all the d orbitals in some species are degenerate; however, they often are not. Sometimes the ligands bound to a central metal cation can split the d orbitals. That is, some of the d orbitals will be at a lower energy state than others. Ligands that have the ability to cause this splitting are called strong field ligands, CN^- is an example of these. If this splitting in the d orbitals is great enough electrons will fill low lying orbitals, pairing with other electrons in a given orbital, before filling higher energy orbitals. In question 7 we had Fe^2+, furthermore we found that there were a certain number (non-zero) of unpaired electrons. Consider now Fe(CN)_6^4-: here we also have Fe^2+, but in this case all the electrons are paired, yielding a diamagnetic species. How can you explain this? A) All the d orbitals are degenerate. B) There is 1 low lying d orbital, which will be filled with two electrons before filling the 4, assumed to be degenerate, higher energy orbitals. C) There are 2 low lying d orbitals, which will be filled with 4 electrons before filling the 3, assumed to be degenerate, higher energy orbitals. D) There are 3 low lying d orbitals, which will be filled with 6 electrons before filling the 2, assumed to be degenerate, higher energy orbitals. E) There are 4 low lying d orbitals, which will be filled with 8 electrons before filling the 1 higher energy orbital.

Explanation / Answer

there are 3 low lying d orbitals (t2g) which will be filled with 6 electrons before filling the 2, assumed to be degenerate, higher energy orbits(eg).

the difference in energy of t2g and eg orbitals is high as cyanide is strong field ligand so pairing up initially takes place at lower t2g orbitals, as in the complex Fe+2 has 6 d-electrons.

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.