Consider the d 6 ion Fe 2+ . a) What is the ground state term (#X) for the d6 fr
ID: 482766 • Letter: C
Question
Consider the d6 ion Fe2+.
a) What is the ground state term (#X) for the d6 free ion (in the absence of a ligand field)?
b) What is the ground state (#Xy) for this ion in a weak octahedral ligand field (small o)?
c) This ground state at small o correlates to which strong-field configuration (t2gxeg*y)?
d) What are the spin-allowed transition(s) for this ion in weak octahedral fields?
e) What is the ground state for this ion in a strong octahedral ligand field (large o)?
f) This ground state at large o correlates to what strong field configuration (t2gxeg*y)?
g) What are the two lowest spin-allowed transition(s) for this ion in strong octahedral fields?
h) Is it possible to distinguish high-spin from low-spin octahedral d6 ions just on the basis of their optical (UV-vis) spectra? (Hint: Count the number of spin-allowed d-d transitions.)
i) Are either the weak-field ground state or the strong-field ground state susceptible to Jahn- Teller distortion (according to the Jahn-Teller theorem)? Will either of these states undergo a large Jahn-Teller distortion? Explain.
Explanation / Answer
b)in octahedral field the d orbitals spilit to low enegry t2g and high energy eg*. since it is weak feild case, cfse is less,so pairing doesnt takes place at lower energy t2g
so ground state is t2g5eg*1
c) t2g6eg*1
d) according to orgel diagram of d6 weak feild.allowed transitiion is from t2g5----->eg5
e)since cfse is so high pairing ocures. at t2g orbital.t2g is the ground statethn.
f)t2g6eg*0
g) possible allowed transition according to tanabe sugano diagram of d6 oh strong field is.
A1g1---->T1g1
A1g1----> T2g1