858.    EYBER, G.  [Photochemical Decomposition of Iron Pentacarbonyl.]  Ztschr. Physik. Chem., vol. 144A, 1929, pp. 1-21; Chem. Abs., vol. 24, 1930, p. 553.

      Eyber has investigated the absorption spectrum of hexane solutions of Fe(CO)₅ and finds strong absorption below about 4,600 Ǻ. U.  The decomposition of the vapor by radiation of wave length, 4,000 Ǻ. U. has been studied.  A quantum efficiency of 2 is found.  This is explained by the postulation of the formation of an activated molecule that reacts with a normal molecule to give CO and Fe₂(CO)₉.  Foreign gases (CO₂, A, N₂ and CO) inhibit the decomposition; a deactivation of the excited molecule may be the reason.

                                              K₁(I_abs.)

d(CO)/dt=  ----------------------------------

                       1+(K₃/K₂).  [(G)/(C)]

where (G) is foreign gas and (C) is pentacarbonyl, satisfies the data.  O₂, if present, alters the reaction.  The vapor-pressure curve from –14° to + 20° has been determined.