Prepare a flask A as follows: Place 30-35 gm of the sodium amalgam provided (3%) into a 100 cm round-bottomed flask with a sidearm. This piece of apparatus is shown in Figure 2a.

Now add approximately 3 grams of the binuclear complex, [Fe(-C₅H₅)(CO)₂]₂, and close the neck of the flask with a Suba seal. Replace the air in the flask with pure nitrogen by alternatively evacuating and then filling with nitrogen three times on the dual vacuum/nitrogen line. (This is the pump-fill method.)

Leave the flask under an atmosphere of nitrogen.