Colloidal iron dispersions prepared via the polymer-catalyzed decomposition of iron pentacarbonyl

Abstract

Stable colloidal dispersions (50-150 A) of zero-valent iron have been prepared by the thermolysis of Fe(CO)5 in dilute solutions of “functional” polymers. The formation of these colloidal dispersions has been rationalized in terms of a locus control formalism for particle nucleation and growth. The functional polymer serves as a catalyst for the decomposition of the metal carbonyl and induces particle nucleation in its domain. Subsequent to particle nucleation, the reaction proceeds in a zero-order fashion indicative of disproportionation of Fe(CO)5 on the surface of the nucleated particles. The thermal decomposition of Fe(CO)5 was studied in solvent alone as well as in the presence of “active” polymers, which react directly with Fe(CO)5, and “passive” polymers, which react with intermediates such as [Fe(CO)4].