I was studying some coordination chemistry and somewhere around the text it was stated that one could know the magnetic moment of a complex from its metal because since all ligands were often diamagnetic, closed shell molecules, the unpaired electrons were centered on the metal anyway. It is implied that the spin of all of those unpaired electrons is the source of the paramagnetism.
So my question is this: From the common isotopes of C, H, N, S, O and P only oxygen-16 and carbon-12 have zero spin. Then why don't the spin of the other nuclei do not contribute to the paramagnetism of the sample the way electrons do? Particularly hydrogen, which is often quite abundant in organic ligands and has a spin of 1/2, same as the electron.