Reference for electronegativities of different metal oxidation states

A long time ago I was researching the effect of the self regulatory response in Fe and Co. I found that my results made sense based on the idea of the electronegativity of the ions considered. I found a webpage that listed the relationship between the different electronegativities for different oxidation states of Fe and Co. 


My problem is I didn't save the webpage and I don't know where I found it. I am not a chemist so I don't know in which kind of books I could find a list of values of electronegativities for different oxidized ions. 


It basically said that the relationship between the electronegativities was something like


$$\ce{Co^2+} < \ce{Fe^2+} < \ce{Fe^3+} < \ce{Co^3+}$$


Note: I don't remember it well, so what I wrote could be lies. The important thing was that there was a flip of order in electronegativities for Fe and Co when changing oxidation state.


Does anyone know where I could find that kind of information? I tried googling, but I am not finding the webpage and don't remember the terms I used to find it in the first place.


I never understood the why of the order either, and I have seen chemist webpages that tell you which ion is more electronegative by just looking at it. If someone could explain that too I would appreciate it.




---


Edit:


I forgot to add that it was in octahedral complexes. I was able to find [this pdf online](http://alpha.chem.umb.edu/chemistry/ch611/documents/Lec2-TheTransitionMetalspostlecture) (page 32) but it doesn't state a reference. [![enter image description here](https://i.stack.imgur.com/BG1fI.png)](https://i.stack.imgur.com/BG1fI.png) 




Pearson conveniently lists cumulative experimental data in the 1988 paper [[1](https://doi.org/10.1021/ic00277a030)], referrring to the earlier work of Moore [2].
Selected values of $I$ (ionization potential), $A$ (electron affinity), $χ$ (absolute electronegativity – probably, that's what you are looking for) and $η$ (absolute hardness) for iron and cobalt cations are:



> 
> **Table I.** Experimental Parameters for Monatomic Cations (eV)
> 
> 
> $$
> \begin{array}{lcccc}
> \hline
> \text{ion} & I & A & χ & η \\
> \hline
> \ce{Fe^2+} & 30.65 & 16.18 & 23.42 & 7.24 \\
> \ce{Fe^3+} & 54.8 & 30.65 & 42.73 & 12.08 \\
> \ce{Co^2+} & 33.50 & 17.06 & 25.28 & 8.22 \\
> \ce{Co^3+} & 51.3 & 33.50 & 42.4 & 8.9 \\ 
> \hline
> \end{array}
> $$
> 
> 
> 


So it looks like the relation is a bit different:


$$\ce{Fe^2+} < \ce{Co^2+} < \ce{Co^3+} < \ce{Fe^3+}$$


Complete table as a screenshot:



> 
> [![Table I - complete](https://i.stack.imgur.com/jnLPR.png)](https://i.stack.imgur.com/jnLPR.png)
> 
> 
> 


### References


1. Pearson, R. G. Absolute Electronegativity and Hardness: Application to Inorganic Chemistry. *Inorganic Chemistry* **1988**, 27 (4), 734–740. <https://doi.org/10.1021/ic00277a030>.
2. Moore, C. E. "Ionization Potentials and Ionization Limits"; *Natl. Stand. Ref. Data Ser.* (*U.S. Natl. Bur. Stand.*); **1970**, NSRDS-NBS 34. ([NIST - PDF](https://nvlpubs.nist.gov/nistpubs/Legacy/NSRDS/nbsnsrds34.pdf))


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