I have been looking at this table for the Magnetic Susceptibility of matal complexes and I noticed an interesting trend:
https://www.gemstonemagnetism.com/uploads/Magnetic_Susceptibilities_of_the_Elements.pdf
It seems that for all complexes which don't have a spin crossover effect (e.g. d0,d10 and some tetrahedral Systems), that the Magnetic susceptibility increases with increasing ligand field strength.
Taking a look at Zinc (II): d10 complex
ZnI2 -108
ZnCl2 -55.33
ZnF2 -34.3
Or Cadmium (II): d10 complex
CdI2 -117.2
CdBr2 -87.3
CdCl2 -68.7
CdF2 -40.6
Or Sodium (I): d0 complex
NaI -57
NaBr -41
NaCl -30.2
NaF -15.6
Or Nickel (II) d8 complex which exhibits a tetrahedral geometry and hence tends to be in the high spin state:
NiI2 +3875
NiBr2 +5600
NiCl2 +6145
NiF2 +2410
Negative numbers for magnetic susceptibility mean the compound is diamagnetic and what you are seeing with different compounds is due to the greater number of electrons that are involved in the diamagnetism the greater the repulsion from the magnetic field. So, you are not dealing with unpaired electrons, just the total number of paired electrons. The greater the number the greater the diamagnetism.
Thank you Joseph S Merola for explaining where the diamagnetic measurments are coming from. Do you know why Nickel tetrahedral complex paramagnetism is increasing? The Magnetic permeability for most other complexes decreases with increasing ligand strength.
Can you tell me what you are using as your ligand strength (or crystal field strength scale)? I just want to make sure we are communicating fro the same point.
Joseph S Merola, I am using the Spectrochemical Series to determine the relative ligand strength https://en.wikipedia.org/wiki/Spectrochemical_series
Tristan Sachsenweger Ballantyne You need to realize that these measurements are being made with the solid salts and not the solutions. So the Ni ions are actually surrounded by an octahedron of the anions. In that no matter the strength of the ligand field, there should be 2 unpaired electrons. The table given really doesn't show a real trend with the sprectrochemical series that I can see.
One more thing Tristan Sachsenweger Ballantyne that I forgot to mention - as your table indicated, the overall measurement is a combination of the paramagnetic and diamagnetic contribution with the paramagnetic usually dominating. But the larger the anion, such as I-, the diamagnetic contribution will be greater so the overall measurement will be somewhat lower.
Joseph S Merola Thank you for your thorough explanations, It helps me understand this field a lot better.
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