In which of the following complexes would you expect the pairing energy to be la
ID: 530802 • Letter: I
Question
In which of the following complexes would you expect the pairing energy to be larger than the orbital splitting energy? Select one: a. [Fe(CN)6]4– b. [FeCl6]4– c. [Fe(CN)6]3– d. [W(CO)6] In which of the following complexes would you expect the pairing energy to be larger than the orbital splitting energy? Select one: a. [Fe(CN)6]4– b. [FeCl6]4– c. [Fe(CN)6]3– d. [W(CO)6] In which of the following complexes would you expect the pairing energy to be larger than the orbital splitting energy? Select one: a. [Fe(CN)6]4– b. [FeCl6]4– c. [Fe(CN)6]3– d. [W(CO)6]Explanation / Answer
Ligands can be arranged in the order of the size of the oct they bring about.
I < Br < S2 < SCN < Cl < NO3 < N3 < F < OH < C2O42 H2O < NCS < CH3CN < py (pyridine) < NH3 <en (ethylenediamine) < bipy (2,2'-bipyridine) < phen (1,10-phenanthroline) < NO2 < PPh3 < CN CO.
[FeCl6]^4- if it could be made ([FeCl4]^2- the stable chloro cmplx of Fe(II)) would be high spin, and although most Fe(II) cmplxs are high spin [Fe(CN)6]^4- is low spin. [2] [Fe(CN)6]^3- and [W(CO)6] are low spin (2nd and 3rd row TM cmplxs are low spin)
So the answer is
b) [FeCl6]^4-.