# Do "weak-field" and "high spin" complexes refer to the same thing?

I will keep it brief; I know that there are weak field, "moderate" 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 "strength" (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.

• @NisargBhavsar Sorry, that's not right. The complex $\ce{[Co(CO)5]}$ does not exist. Apr 23, 2021 at 8:26
• Also, @ajent what do you mean by "weak-field complex"? Ligands can be weak or strong-field and complexes can be low or high-spin. I have never seen complexes referred to as weak or strong-field. Apr 23, 2021 at 8:30
• There is no such thing as a weak-field complex. || @NisargBhavsar There is no such thing as [Co(CO)6] either. Cobalt forms a dinuclear carbonyl: Co2(CO)8. en.wikipedia.org/wiki/Dicobalt_octacarbonyl Apr 23, 2021 at 11:12
• @ShoubhikRMaiti sorry for the late response, I have been busy. I'm trying to understand a question on my homework for this class; the way it's worded implies that the complex itself be labeled as weak-field or strong-field, rather than merely the ligand. I assume this is just a grammatical problem if it is inappropriate to call the complex itself weak-field or strong-field. Apr 25, 2021 at 23:58