Calculated Molecular Properties of Triangular Tribenzo and Perfluoro-Tribenzo Trimercuronin Macrocycles

Abstract

Trimeric perfluoro-ortho-phenylene mercury(II) cluster is a prototypical example of a macrocyclic multidentate Lewis acid. In this study we report the electronic structure, the calculated absorption and vibrational spectra via all-electron scalar and spin-orbit relativistic DFT calculations for [Hg(o-C6H4)]3 (1), [Hg(o-C6F4)]3 (2), and the dimeric form of 2, ([Hg(o-C6F4)]3)2 (3). Due to the inclusion of the spin-orbit interaction, double point groups were used (D3h* and D3d*). The calculations suggest small paratropic ring currents at the center of 1 and being smaller for 2 due to the withdrawn properties of the perfluorated ligand. The luminescent properties of the solid state of 2 are well represented by the postulated model of dimer 3, which mimic the solid state, where the proposed mechanism involves a vibronically coupled emission process. The calculated lambda(absorption)max of 3 show an intense peak at 347 nm, which compares well with the reported band at 355 nm; also, the calculated lambda(emission)= 431 nm is close to the experimental value of 440 nm. Moreover, the calculated structural changes of the first excited state (3*) are reflected in the large value of the calculated Stoke shifts of 84 nm, which is in quite good agreement with the value of 85 nm extracted from the experimental data.

Vibrational and DFT analysis of perfluoro-o-phenylenemercury compounds

“…The most interesting feature of the compound 1 is the Hg 3 core, where the proximity of mercury (II) centers (3.62 Å) produce Hg$$$H interactions and is responsible of the remarkable Lewis acidity of 1 [5]. Vibrational detection of metallophilic interactions is not commonly reported.…”

“…4) This system has the same D 3h symmetry of 1 and contains the same (C 2 Hg) 3 framework. Theoretical evaluation of metallophilic interaction must consider accurately electronic correlation effects and take in account dispersion interactions [5,17,18]. For this reason we optimized and calculated vibrational modes for the (C 2 H 2 Hg) 3 system with the DFT-c method and at MP2 level.…”

“…Usually infrared spectra of 1 [4] in his molecular complexes are reported, but a detailed vibrational analysis doesn't exist; for this reason no effect of coordinated guests onto vibrational spectra of 1 are reported, although vibrational spectroscopy is a very useful approach in evaluation of intermolecular interactions. A computational modeling of electronic spectra [5] report only a partial assignment of some modes. Considering the great interest for this compound we recorded complete vibrational spectra (infrared an Raman) and calculated DFT vibrational modes in order to propose an assignment.…”

Advances in bonding and properties of inorganic systems from relativistic calculations in Latin America

“…The calculated spectroscopic properties of trimeric perfluoro‐ortho‐phenylene mercury(II) cluster, [Hg(o‐C 6 F 4 )] 3 , show luminescent behavior in the solid state, but not in solution. The calculated data from relativistic calculations, involving the spin‐orbit coupling, are in satisfactory agreement with the reported data, showing that the luminescent behavior in solid state involves a dimer with a vibronically coupled emission process. For the dimer model of the solid state ([Hg(o‐C 6 F 4 )] 3 ) 2 , the absorption maxima involved LMCT transition, which promoted the decrease of the centroid‐centroid distance and the subsequent emission coupled with a non‐radiative vibrational process, as shown in Figure .…”

“…The lifetime of the emission processes were calculated, and the values are in the same order as the experimental reports. [133] The calculated spectroscopic properties of trimeric perfluoro-ortho-phenylene mercury(II) cluster, [Hg(o-C 6 F 4 )] 3 [134] showing that the luminescent behavior in solid state involves a dimer with a vibronically coupled emission process. For the dimer model of the solid state ([Hg(o-C 6 F 4 )] 3 ) 2 , the absorption maxima involved LMCT transition, which promoted the decrease of the centroid-centroid distance and the subsequent emission coupled with a non-radiative vibrational process, as shown in Figure 11.…”