Joint X-ray spectroscopic and quantum-chemical study of the electronic structure of pentafluorophenylalkyl ethers

The high resolution X-ray emission O-K alpha spectra of pentafluorophenylal kyl ethers C6F5OR (R = Et, Pr-i, and Bu-t) exhibit differences related to a change in the electronic structure of the compounds as R is varied. The se arch for stable conformers was performed by the semiempirical PM3 method. T he most probable structures of C6F5OR were determined by the comparison of the experimental and theoretical X-ray spectra plotted for each conformer u sing ab initio calculations in the 6-31G basis set. Substituent R in pentaf luorophenylalkyl ether; is situated outside of the ring plane. The fluorina tion of the benzene ring changes the energy level of the lone electron pair of oxygen relative to the levels of orbitals of the ring and substituent R and leads to an increase in the efficiency of interactions in the sigma-sy stem.