# Chemical reaction and shift in magnetic susceptibility sign

I'm trying to find an easy experiment involving a chemical reaction in which two paramagnetic reactants A and B react to give a product which is diamagnetic (or the reverse). The idea is to show that A is paramagnetic, B is paramagnetic, but A+B --> C is diamagnetic.

Or, another experiment: an experiment in which a change in temperature changes paramagnetic to diamagnetic (or the reverse). I've seen such an experiment but cannot remember the details. All I can say is that there was a color change and, at the same moment, a paramagnetic/diamagnetic shift

• Thermal decomposition reactions which produce oxygen would satisfy your requirement since oxygen is diamagnetic, right. – DHMO Jan 21 '17 at 4:33
• Oxygen in its ground state is famously paramagnetic! For OP: for the second part of your question, you may be interested in complexes which can undergo spin transitions, in particular the $\mathrm{d^6}$ Fe(II) complexes. High-spin Fe(II) is paramagnetic, but low-spin Fe(II) is diamagnetic. en.wikipedia.org/wiki/Spin_transition Also how about Ni(II) complexes $\ce{Ni(PPh3)2X2}$ which can flip between square planar (diamagnetic) and tetrahedral (paramagnetic) geometry? I don't know much about those so just putting them out there. – orthocresol Jan 22 '17 at 15:45