91- 6303239042
Boundary Configurations:
$$\begin{aligned} &\mathbf{\text{Co}^{3+} \text{ Exception (}d^6\text{):}} \\ &\quad \Delta_o > P \implies \text{Forces pairing with: } \text{H}_2\text{O}, \text{ox}^{2-}, \text{NH}_3, \text{en} \\ &\quad \text{Configuration: } t_{2g}^6 e_g^0 \\ &\quad \text{Magnetic State: } \text{Low-spin / Diamagnetic} \\ \\ &\mathbf{\text{Fe}^{3+} \text{ Contrast (}d^5\text{):}} \\ &\quad \Delta_o < P \implies \text{No pairing with: } \text{H}_2\text{O}, \text{ox}^{2-} \\ &\quad \text{Configuration: } t_{2g}^3 e_g^2 \\ &\quad \text{Magnetic State: } \text{High-spin / Paramagnetic} \end{aligned}$$
Concept: Highlights critical boundary states for $$d^4$$ to $$d^7$$ metal ions where intermediate ligands alter their field behavior based on the specific charge-to-size ratio of the central transition metal ion.
Notation:
- $$\text{ox}^{2-}$$ = Oxalate ion;
- $$\Delta_o$$ = Octahedral splitting energy parameter;
- $$P$$ = Electron pairing energy threshold.
