Do "weak-field" and "high spin" complexes refer to the same thing? I will keep it brief; I know that there are weak field, &quot;moderate&quot; field, and strong field ligands and that these might contribute to a complex being high or low spin overall. My question is, does a complex having high spin indicate a weak field complex, regardless of ligand &quot;strength&quot; (or vice versa)?
For example, $\ce{[Fe(H2O)6]^3+}$ has a moderate strength ligand ($\ce{H2O}$) but is overall a high spin complex, so would $\ce{[Fe(H2O)6]^3+}$ be considered a weak field complex, despite the ligand strength not being weak? If not, is it only appropriate to call it a high spin complex? Thank you.
The spectrochemical series only gives info on the relative strength of the ligand field. Whether or not a metal complex is high or low spin (assuming there is an appropriate number of d electrons that both are possible) is a function of both the ligand and the metal center.
Thus, it is possible for &quot;weak field&quot; ligand to be in a low spin complex if the metal center favors low spin. For example, almost all complexes of second and third series transition metals are low spin, independent of ligand identities.