Yes / A 16-electron iridium organometallic is reacted with carbon monoxide to form an 18-electron CO-adduct. This CO-adduct is stable for weeks in the solid state, but quickly reverts to its parent 16-e complex in tetrahydrofuran solution, releasing CO(g). Using a simple methodology, we show that this gas can subsequently be used to perform a carbonylation reaction on another molecule. / Royal Society; Academy of Medical Sciences/the Wellcome Trust/the Government Department of Business, Energy and Industrial Strategy/the British Heart Foundation Springboard Award