[c0d3]

Cadmium is d10. Is it possible to have a paramagnetic d10 complex? What can i read to find out about this? Thanks

[cth]

To have paramagnetism, you need at least one unpaired electron. But for cadmium, the 4d shell is full and all electrons are paired. So I don't think it is possible to have a paramagnetic Cd²⁺.

This being said, the cadmium complex as a whole may be magnetic if the unpaired electron is carried by something else than the cadmium:
- another metal (like manganese, iron,...) coordinated to the complex along with cadmium
- the ligand being a radical (tricky to do because radicals are usually very unstable)

[c0d3]

In my case, i have no other metal except cadmium in my complex. My ligand is made from C,H,N,S. So i don't understand how it could be paramagnetic. I know it's paramagnetic from the gouy balance. Really appreciate if someone can enlighten me on this. Thanks to cth anyway but what i looking for is more

[cth]

My first thought would be of a paramagnetic impurity in your compound. Did you use any paramagnetic transition metal or lanthanide at some point during the ligand synthesis? Perhaps some of it remains.

Or else your ligand is a radical http://en.wikipedia.org/wiki/Radical_(chemistry), which is less likely but still possible.

You could check for it doing a EPR measurement http://en.wikipedia.org/wiki/Electron_paramagnetic_resonance. It would allow you to tell the difference between metal and radical.

[c0d3]

As far as i am certain of, i have only cadmium in my complex. My ligand being radical also not likely. According to previous work, my ligand mostly would be uninegative or neutral in some case. I don't think we have a EPR machine here. So, any other thoughts you can provide? Thanks again for paying attention in my case.

[cth]

As far as i am certain of, i have only cadmium in my complex.

OK, if you're sure there is no metal impurity and you have it all covered, then the magnetism can only come from the ligand.

No need to describe the ligand entirely, but what about the group that is directly coordinated to the cadmium centre. What is it? Pyridine? Thiol?... You mentioned the ligand contain C, H, N and S. I wonder if you have something like that:

-C=C-
  |  |
HS  SH

The cadmium being coordinated to the sulfur atoms. Do you have a group in your ligand that looks like that?

If so, there is possibility of a two-electron redox process similar to this one http://en.wikipedia.org/wiki/File:1,2-benzoquinone_to_catechol.png (replace the oxygen atoms by sulfur ones). With a metal coordinating both sulfur atoms, a one electron redox process can occur, forming a radical.

The best characterisation method is definitely EPR. You would need to do some CV (cyclic voltammetry) as well if you have the double thiol-group I described above, in order to determine its redox potentials. And maybe some SQUID measurement if you think you have long-range magnetic order like anti-ferromagnetism,...