Over time, the iridium compound changes into a different structure that can swap hydrogen atoms in molecules, which is useful for making labeled compounds for medical imaging.

The binuclear iridium compound can swap hydrogen atoms in pyridine molecules at specific rates, with the ortho position exchanging fastest.

The iridium compound has parts that move around quickly at room temperature, with pyridine molecules leaving at about 8 times per second and hydrogen atoms swapping positions about 3.6 times per second.

In the binuclear iridium compound, different pyridine molecules swap places at different speeds, which seems to be related to how tightly they're attached to the iridium atoms.

The iridium compound loses a pyridine molecule to form a simpler structure that helps transfer polarization during the SABRE process.