Studies of substituent effects on the electronic structure and related properties of [Ru(phen)3]2+ with DFT method

Abstract

Studies on the complex [Ru(phen)3]2+ (phen=1,10-phenanthroline) and its 5,6-di-substituted derivates are carried out using DFT method and B3LYP/LanL2DZ level of theory. The trends in the substituent modification effects caused by the electron-pushing group (OH) and the electron-withdrawing group (F), on the electronic structure and related properties, e.g. the components and the energies of some frontier molecular orbitals, the spectroscopy characteristics, and the net charge populations of some main atoms of the complexes, etc, have been investigated. The computational results show: First, the substituents have some interesting effects on the excited state characteristics of complexes. For the excited states of the complexes, the electron-withdrawing group (F) can activate the main ligand and passivate the co-ligands, whereas the electron-pushing group (OH) can activate different sites of the main ligand (relative to the ground state). Second, both the electron-pushing group (OH) and the electron-withdrawing group (F) can cause a red shift in the electronic ground band. Third, the following characteristics of the atomic charge populations can been seen: Along path (a) R→C5→C12→C11→N1, the atomic negative charges fully alternate with the atomic positive charges for I (ROH) and III (RF), and the extent of alternation is greater for III than for I. However, such a atomic charge alternation does not obviously exist for II (RH). Along path (b) R→C5→C12→C4→C3→C2→N1, the atomic charge populations incompletely show alternation for I and III. Changing substituent R can greatly influence charge populations on its neighboring atoms, but it only slightly influences those on farther atoms. Such complicated characteristics of the charge populations in the complexes can be explained by the law of polarity alternation and the idea of polarity interference.