The kinetics and energetics of tungsten hexacarbonyl and cyclopentadienyl manganese tricarbonyl, reactions with olefin molecules in the gas phase
Abstract
The photochemistry of transition metal carbonyls is an actively studied field, in part, because of the wide variety of synthetic and catalytic precursors that can be generated during photolysis. Many catalytic processes are induced by these species including hydrogenation, hydrosilation, and isomerization of olefins. To understand these types of reactions we must know the energetics and dynamics of the bond making and bond breaking processes. Unfortunately, while significant information has been gained in the area of fundamental kinetic parameters, almost no progress has been made in the examination of the basic energetics of these complex processes. The kinetic study of reactions of isolated unsaturated molecules in the gas-phase offers the advantage of a perspective on energetics and dynamics that is free from solvent effects. In the gas-phase the interaction between a potential ligand and an isolated nonsolvated unsaturated species can be studied in detail. This thesis reports the investigation of the elementary kinetics and energy barriers for the unimolecular decay of W(CO)$\sb5$(olefin) and CpMn(CO)$\sb2$(olefin) systems. W(CO)$\rm\sb5(C\sb3H\sb6)$ and W(CO)$\rm\sb5(C\sb2H\sb4)$ are unstable in the gas phase and react with CO by dissociative substitution. Differences in reactions rates compared with Cr(CO)$\sb6$ are analyzed in terms of possible structural variations in critical configuration. Implications for trends in photocatalyzed reactions are considered. We also report the generation of gas phase CpMn(CO)$\sb2$(olefin) complexes for a series of increasingly branched olefin ligands. The stability of these complexes correlates strongly with steric hindrance. We find that infrared spectra of CPMn(CO)$\rm\sb2(C\sb2H\sb4)$ and CPMn(CO)$\rm\sb2(C\sb3H\sb6)$ complexes agree well with solution phase data.
Degree
Ph.D.
Advisors
Grant, Purdue University.
Subject Area
Chemistry
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