An experimental and theoretical study of the electronic spectra of tetraethylammonium [tris(1,3-dithiole-2-thione-4,5-dithiolato)M] and tetraethylammonium [tris(1,3-dithiole-2-one-4,5-dithiolato)M], for M = Sn(IV) and Sb(V)

Abstract

Metal-dmit complexes and related compounds have been studied extensively over the last few decades. Experimental reports of its UV-Vis spectra present the main spectroscopic features, although many details of the electronic structure still have to be investigated. This work presents a detailed analysis of the UV-vis spectra of the [NEt4]x[M(L)3] (L = dmit and dmio), for M,x = Sn,2 and Sb,1. The experimental spectrum was deconvoluted and analyzed with B3LYP and CAM-B3LYP DFT methodologies. The results lead to an assignment of several bands involving LMCT, besides confirming the presence of a metal orbital in the HOMO-LUMO boundary, with additional observation performed through the analysis of the dmio complex in order to enhance the results. Several methods such as EDA, NBO, and QTAIM were applied to determine the covalent character of the metal-ligand interaction. Furthermore, the solvent effect was evaluated using the CPCM model to observe the changes in the overall properties.