Trimethylamine N-oxide (MeNO) can be used in the nucleophilic abstraction of carbonyl.  There is an nucleophilic attack of MeNO on the carbon of the carbonyl group which pushes electrons on the metal.  The reaction then proceeds to kick out CO and NMe.
An article from the Bulletin of Korean Chemical Society journal showed interesting results where one iridium complex undergoes carbonyl abstraction while a very similar iridium complex undergoes hydride extraction.