Graduate Program
Chemistry
Degree Name
Master of Science (MS)
Semester of Degree Completion
2012
Thesis Director
Sean Peebles
Thesis Committee Member
Doug Klarup
Thesis Committee Member
Mark McGuire
Thesis Committee Member
Kraig Wheeler
Abstract
A complementary blend of computational and spectroscopic methods has been used to analyze three halomethane complexes which exhibit different types of internal motion. In CH2FrCO2, the CH2F2 undergoes a "rocking" motion which inverts the dipole moment component along the c axis. For thjs complex, the spectra of six isotopologues were measured and an experimental structure was determined (see figure). The barrier to inversion was 142(3) cm·1 based on an experimental AE (AE is the energy difference between v=0+ and v=ff), which is in good agreement with the ab imtio ZPE-corrected barrier of 122 cm •1 . Upon comparison with similar complexes, a trend was established where the magrutudes of dipole/quadrupole moments and barrier for internal motion are indirectly proportional. The other two complexes, CHBrFrH 2O and CHCIF2-H2O, revealed an internal rotation of the water molecule. The spectra of two isotopologues (79Br and 81Br) of CHBrFrH 2O were assigned, and an approximate structure was determjned (see figure). A barrier to internal rotation for each complex was determined using a AE value of 16008(416) MHz: 115(14) cm·1 for CHBrF2-H2O and 105(10) cm·1 for CHClF2-H2O, which are consistent with the ab initio predictions for each species. Analysis of a series ofhalomethane-water complexes revealed that the dipole moment of the halomethane, the halogen-hydrogen distance, and barrier energy are indirectly proportional.
Recommended Citation
Thomas, Amelia J., "Internal motion in weakly bound halomethane complexes" (2012). Masters Theses. 935.
https://thekeep.eiu.edu/theses/935
