DFT/TDDFT computational study of the structural, electronic and optical properties of rhodium (III) and iridium (III) complexes based on tris-picolinate bidentate ligands

Abstract

The electronic structures and spectroscopic properties of two complexes [M(pic)] (M = Ir, Rh) containing picolinate as bidentate ligands have been calculated by means density functional theory (DFT) and time-dependent DFT/TD-DFT using three hybrid functionals B3LYP, PBE0 and mPW1PW91. The PBE0 and mPW1PW91 functionals, which have the same HF exchange fraction (25%), give similar results and do not differ drastically from B3LYP results. Calculated geometric parameters of the complexes are in good agreement with the available experimental data. The UV absorptions observed in acetonitrile were assigned on the basis of singlet state transitions. The most intense band observed in the UV-C region corresponds to ligand-to-ligand charge transfer states (LLCT) in both complexes. The theoretical spectrum of the rhodium complex is characterized by a large degree of mixing between metal-to-ligand-charge-transfer (MLCT), LLCT and metal centered (MC) states in the UV-A region. The presence of low-lying excited states with MC character affects the absorption spectrum under spin-orbit coupling (SOC) effects and play important roles in the photochemical properties. Graphical abstract Frontier molecular orbital diagram of mer-M(pic) (M=Ir, Rh).

Theoretical Investigation of Iridium Complex with Aggregation-Induced Emission Properties

“…The PBE0 functional is often used in calculations for transition metal complexes, including iridium complexes, and has been shown to accurately reproduce the electronic spectra and geometry of such compounds [52][53][54][55][56][57][58]. The def2-TZVP, (8s7p6d1f)/[6s4p3d1f], basis set with the appropriate ECP was used for iridium, while for carbon, nitrogen, and oxygen, the TZVP basis, (11s6p1d)/[5s3p1d] and (5s1p)/[3s1p], for hydrogen was used [59,60].…”

Solvatochromism and Theoretical Studies of Dicyanobis(phenylpyridine)iridium(III) Complex Using Density Functional Theory

“…In all calculations, an extensive basis set was used, consisting of 6-311G** [11][12][13][14] on all atoms (C, H, N, O) apart from iridium, which was described using a Stuttgart-Dresden pseudo-potential [15][16][17][18]. Besides, bulk solvent effects were treated via the polarizable continuum model (PCM) [19][20][21][22]. Finally, all calculations were run using ultrafine integrals, and no symmetry was considered in the calculations.…”