Substituent effects on the structure and properties of (para-C5H4X)Ir(PH3)3complexes in the ground state (S0) and first singlet excited state (S1): DFT and TD-DFT investigations

The ground and lowest singlet excited state geometries of selected (para-C5H4X)Ir(PH3)(3)iridabenzene complexes (para-substituent = NH2, OMe, Me, H, F, Cl, CCl3, CF3, NO2) are optimized using the MPW1PW91 procedure employing the LanL2DZ(Ir) and 6-311G(d, p) (C, H, N, O, P, F, Cl, P) basis sets. The excited state is generated using the time-dependent density function method. The effects of electron-donating groups and electron-withdrawing groups on the energy, atomization energy, rotational constants, and frontier orbital energies in the first singlet excited state (S-1) of iridabenzene are investigated and compared to those of the ground state (S-0). The Ir-C and Ir-P bonds in the studied molecules are analyzed by electron localization function and localized-orbital locator methods. The correlations between the Ir-C and Ir-P bond distances, electron localization function, and localized-orbital locator values Hammett constants (sigma(p)) and dual parameters (sigma(I)and sigma(R)) are given for the two studied states. Thepara-delocalization index is used for investigation of the aromaticity of the studied complexes.