njit-etd2003-111 - New Jersey Institute of Technology

properties are used in evaluation and comparison of C1 2 + R. Cl + RCA reaction rate
constants from the kinetics literature for comparison with empirical analysis. Data from
some 20 reactions in the literature show linearity on a plot of Eafwd vs. AH.,fwd, yielding
a slope of (0.38 ± 0.04) and an intercept of (10.12 ± 0.81) kcal/mol.
The use of Density Functional Theory, B3LYP/6-31g(d,p), with isodesmic
working reactions for enthalpy of formation of sulfur hydrocarbons is evaluated using a
set of known sulfur hydrocarbon / radical species. Thermodynamic and kinetic
parameters for reactants, transition states, and products from unimolecular dissociations
of sulfur species related to the chemical agent: CH3CH2SCH2CH3, CH3CH2SCH2CH3,
and CH3CH2SCH2CH3 and corresponding radicals are analyzed. Standard enthalpy,
AHf°298, for the molecules and radicals are determined using isodesmic reaction analysis
at the B3LYP/6-31G(d,p) level, with S°298 and Cp(T) determined using geometric
parameters and vibrational frequencies obtained at this same level of theory. Potential
barriers for the internal rotor potentials are also calculated at the B3LYP/6-31G(d,p)
level, and the hindered rotation contributions to S°298 and Cp(7) are calculated.