I need help checking my answers for my Inorganic chemistry course, and I've run into a few things that I am unsure of. I would very much appriciate if somebody could check my reasoning in this problem.
The task is to compare the LFSE of three pairs of metal complexes, and determine which complex has the highest LFSE. The pairs are:
- [Cr(OH2)6]2+ vs. [Cr(OH2)6]2+
- [CrCl6]3- vs. [Cr(NH3)]3+
- [Ni(OH2)]2+ vs. [Ni(en)3]3+
I have put down the electron configurations of the complexes as follows in the list below, and calculated the LFSE from the formula LFSE = -0,4x + 0,6y, if x is the number of electrons in the t2g
-orbitals, and y is the number of electrons in eg
- [Cr(OH2)6]2+: t2g3eg1, LFSE = -0,6
- [Cr(OH2)6]2+: t2g3eg0, LFSE = -1,2
- [CrCl6]3-: t2g3eg0, LFSE = -1,2
- [Cr(NH3)]3+: t2g3eg0, LFSE = -1,2
- Ni(OH2)]2+: t2g6eg2, LFSE = -1,2
- [Ni(en)3]3+: t2g6eg2, LFSE = -1,2
As you can see, the last two pairs of complexes then have the same LFSE, which makes me think I have made a mistake somewhere. I am also concerned about the first pair, as a higher oxidation number is supposed to create a higher (more positive?) LFSE with the same ligands, and here the loss of a electron makes it lower.
Any feedback is much appreciated. Cheers!