What happens as a result of the interaction of CaO and CO?

Carbon monoxide is capable of reacting as Lewisic acid or base with many metal oxides. On the surface of thermally activated calcium oxide, carbon monoxide is adsorbed with the formation of various compounds containing (CO) x-anions.
Unstable linear and cyclic carbonyl complexes O-C-Ca-O isocarbonyl complexes C-O-Ca-O can form on the surface of calcium oxide.
In contrast to the reaction of calcium oxide with carbon dioxide, forming calcium carbonate, as a result of the interaction with carbon monoxide, stable compounds, in addition to the above-described complexes at the interface, are not formed.