Theoretical studies on the structures and absorption spectra of–C_nR_2n+1(R = H, F; n = 1, 2) substituted 5-(2-pyridyl) pyrazolate boron complexes

Abstract

The molecular structures, electronic structures and absorption characters of–CH₃,–C₂H₅,–CF₃,–C₂F₅ substituted 5-(2-pyridyl) pyrazolate boron complexes were presented by density functional theory (DFT). The ground state structures of the title complexes were optimised at B3LYP/6-31G* level. In addition, a time dependent density functional theory (TD-DFT) method is applied to investigate the properties of absorption spectra and electronic transition mechanism which were based on the ground state geometries. The results show that the chemical bond formed between nitrogen in the pyridyl ring and boron can be attributed to coordination effect. The boron centre has a typical tetrahedral geometry with the adjacent atoms. The calculated absorption wavelengths for–CF₃,–C₂F₅ substituted 5-(2-pyridyl) pyrazolate boron complexes are in good agreement with the experimental data.

Keywords:

• boron compounds
• absorption spectra
• DFT calculations
• HOMO-LUMO gaps

Acknowledgements

This work is supported by the Training Fund of NENU's Scientific Innovation Project (NENU-STC07016). We are greatly thankful for the referees' helpful comments.