The Vapor Pressure of Iron Pentacarbonyl

Vapor pressure measurements have been made on pure iron pentacarbonyl between +31° and −19°C. The experimental results may be expressed in the form log 10 p ( mm Hg ) = − ( 2096.7 ° K / T ) + 8.4959 which corresponds to a heat of vaporization for the liquid carbonyl of ° H = ( 9.588 ± 0.12 ) kcal / mole . This result confirms and extends the earlier measurements made by Trautz and Badstiibner(2) between 0° and 140°C. The need for careful purification of commercially available iron pentacarbonyl is emphasized, particularly for establishing the correct vapor pressure below 45°C.