Geometry optimization and UV/Vis spectra of organometallic chalcones functionalized with a benzo‐15‐crown‐5 fragment: A DFT/TD-DFT investigation

Abstract

In this paper, we studied the structural and UV–visible absorption spectrum of the organometallic chalcones from ferrocene and cyrhetrene functionalized with a benzo‐15‐crown‐5 fragment. The influence of different alkali and alkaline earth metal ions on geometric structures, frontier molecular orbitals character, gap energy and electronic absorption spectra of [(η5-C5H4C(O)CH = CH-4-benzo-15-crown5)MLn] (MLn = Fe(η5-C5H5) and Re(CO)3) has been theoretically studied by density functional theory (DFT) and time-dependent density functional theory (TDDFT) calculations with PBE0 and CAM-B3LYP hybrid functionals. Calculated geometric parameters of studied complexes are in good agreement with the available experimental values. The theoretical absorption spectra reproduce the main properties of the experimental spectra. Both alkali (Li+, Na+, K+, Rb+ and Cs+) and alkaline-earth (Be2+, Mg2+ and Ca2+) metal ions selective complexes have been theoretically identified. The calculated values the lowest energy band (λmax) of the crown ether derivatives to the alkaline earth metal cations increases from Be, Mg, and then Ca in the complexes [2 M], indicating that these absorption bands are associated to a transition from the HOMO to LUMO transition, which is assigned to metal-to-ligand charge transfer (MLCT).