Sonolysis induced decomposition of metal carbonyls: kinetics and product characterization

Ultrason Sonochem. 2004 Sep;11(6):385-92. doi: 10.1016/j.ultsonch.2003.10.009.

Abstract

The decomposition kinetics of Fe(CO)5 and Mo(CO)6 induced by sonolysis in hexadecane solvent was studied as a function of temperature (303-343 K) under an inert atmosphere. The decomposition data, obtained over at least two half lives in most of the runs, yielded first-order rate constant (k) values with correlation co-efficient (R2) > 0.95. The products were characterized by various spectroscopic techniques. The transmission electron microscopy (TEM) yielded images from which the mean particle diameter (MPD) of approximately 10 nm for Fe and < 3 nm for Mo were estimated. The generation of amorphous Fe and semi-crystalline Mo particles was determined from line broadening and corresponding d-spacing values in the X-ray diffraction (XRD) spectra. The XAFS/XANES data were consistent with the production of Fe(0) metal but carbided Mo (Mo2C). The one-step production of high-yield pyrophoric products demonstrated the applicability of sonolysis to effectively produce gram-quantity of zero-valent metals.