Substituent effects on the structure and properties of (para -C5H4X)Ir(PH3)3 complexes 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 (S1) of iridabenzene are investigated and compared to those of the ground state (S0). 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 (σp) and dual parameters (σI and σR) are given for the two studied states. The para -delocalization index is used for investigation of the aromaticity of the studied complexes. [ABSTRACT FROM AUTHOR]