[mgbee]

I'm trying to work out what coordination geometry a series of nickel complexes are. I have calculated all the magnetic measurements and I know that one complex is diamagnetic and square planar and the other two are paramagnetic.
I am stuck on what to do next as to figure out whether they are octahedral, tetrahedral.
help appreciated
thanks

ok update:
I know all of the geometries for the complexes, I am just having trouble understanding between the square planar and tetrahedral fields.
The diamagnetic complex is in a square planar environment and a paramagnetic complex is in the tetrahedral.
I dont understand how you can tell that whether it is square planar or tetrahedral?

[cth]

Magnetic measurements tell you if you have unpaired electron(s) (paramagnetic) or not (diamagnetic).

Now, you take the related crystal field diagrams http://en.wikipedia.org/wiki/Crystal_field_theory and fill in the number of electrons from nickel. You should find that in one case all electrons are paired, while in the other case you have two unpaired electrons.