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Homogeneous Decomposition Mechanisms of Diethylzinc by Raman Spectroscopy and Quantum Chemical Calculations
 

Summary: Homogeneous Decomposition Mechanisms of Diethylzinc by Raman Spectroscopy and
Quantum Chemical Calculations
Young Seok Kim, Yong Sun Won, Helena Hagelin-Weaver, Nicolo´ Omenetto, and
Tim Anderson*,
Department of Chemical Engineering and Department of Chemistry, UniVersity of Florida,
GainesVille, Florida 32611
ReceiVed: October 26, 2007; In Final Form: December 19, 2007
The gas-phase decomposition pathways of diethylzinc (DEZn), a common precursor for deposition of Zn-
VI compounds, were investigated in detail. The homogeneous thermal decomposition of DEZn in N2 carrier
was followed in an impinging-jet, up-flow reactor by Raman scattering. Density Functional Theory calculations
were performed to describe the bond dissociation behavior using the model chemistry B3LYP/6-311G(d) to
estimate optimal geometries and Raman active vibrational frequencies of DEZn, as well as anticipated
intermediates and products. Comparison of the measured DEZn decomposition profile to that predicted by a
2-D hydrodynamic simulation revealed that simple bond dissociation between zinc and carbon atoms is the
dominant homogeneous thermal decomposition pathway. The calculations suggest several reactions involving
intermediates and Raman scattering experiments confirming the formation of the dimer (ZnC2H5)2. In a different
set of experiments, photolysis of DEZn gave evidence for decomposition by -hydride elimination. The results
suggest that -hydride elimination is a minor pathway for the gas-phase homogeneous pyrolysis of diethylzinc.
A reasonable transition state during -hydride elimination was identified, and the calculated energies and
thermodynamic properties support the likelihood of these reaction steps.

  

Source: Anderson, Timothy J. - Chemical Engineering Department, University of Florida

 

Collections: Materials Science