Diiridium Bimetallic Complexes Function as a Redox Switch To Directly Split Carbonate into Carbon Monoxide and Oxygen

A pair
of diiridium bimetallic complexes exhibit a special type
of oxidation–reduction reaction that could directly split carbonate
into carbon monoxide and molecular oxygen via a low-energy pathway
needing no sacrificial reagent. One of the bimetallic complexes, IrIII(μ-Cl)2IrIII, can catch carbonato
group from carbonate and reduce it to CO. The second complex, the
rare bimetallic complex IrIV(μ-oxo)2IrIV, can react with chlorine to release O2 by the
oxidation of oxygen ions with synergistic oxidative effect of iridium
ions and chlorine atoms. The activation energy needed for the key
reaction is quite low (∼20 kJ/mol), which is far less than
the dissociation energy of the CO bond in CO2 (∼750
kJ/mol). These diiridium bimetallic complexes could be applied as
a redox switch to split carbonate or combined with well-known processes
in the chemical industry to build up a catalytic system to directly
split CO2 into CO and O2.