THEORETICAL STUDY ON ELECTRONIC STRUCTURES AND SPECTROSCOPY OF TRIARYLBORANE SUBSTITUTED BY THIOPHENE
AbstractThe electronic structures of a series of triarylborane derivatives were studied using the AM1 method and density function theory (DFT) at B3LYP/6-31G(d) level. Based on the B3LYP/6-31G(d) optimized geometries, the electronic spectra, IR and 13C NMR spectra of these compounds were calculated with the INDO/CIS, AM1 and B3LYP/6-31G(d) methods, respectively. The presence of electron-donating alkyl groups and the increase in the number of thiophene rings in the derivatives lead to the decrease in LUMO-HOMO energy gaps. At the same time, the first absorptions in the electronic spectra and the stretching vibrations of the C-C as well as C-H bonds in the IR spectra of these compounds compared with those of the parent compound are red-shifted. Also, the 13C chemical shifts of the carbon atoms on the phenyl rings in these compounds are upfield relative to those of the same carbon atoms in the parent compound.
KEY WORDS: Triarylborane, LUMO-HOMO energy gaps, Red-shift, B3LYP/6-31G(d) Bull. Chem. Soc. Ethiop. 2009, 23(1), 77-83.