A theoretical study on the anionic metal bis(ditholate) complexes[M(S۲C۲R۲)۲]۲–(M=Zn(II), Cd(II), Hg(II); R=H, CH۳, CN)

Metal bis-dithiolene complexes have indeed been the subject of extensive study by chemistsin both the inorganic and organic fields in recent decades. This is due to their wide range ofapplications in various areas, including conducting and magnetic molecular materials, as well astheir relevant optical properties [۱].Dithiolenes exist in three different forms with varyingcharges, which contribute to their redox activity and ability to form highly electron-delocalizedcomplexes. However, the term dithiolene is used without taking into account the formaloxidation state of ligands to describe their noninnocent character in several metal complexes[۲].In this work, the interactions between the fragments in metal bis(۱,۲-dithiolate) complexescomplexes [ML۲]۲– (M=Zn(II), Cd(II), Hg(II); L= S۲C۲H۲۲− (edt۲‒), S۲C۲Me۲ ۲ − (dmedt۲‒),S۲C۲(CN)۲۲− (mnt۲‒)) have been investigated,at BP۸۶/def۲-TZVP and M۰۶/def۲-TZVP levels oftheory. Four types of interaction energies between the fragments as well as the total interactionenergies of the complexes [۳‒۵]were calculated and compared. An Energy DecompositionAnalysis-Natural Orbital for Chemical Valence (EDA-NOCV) was also performed to study thenature of metal−bis(dithiolate) interactions in these complexes.The results showed that amongthe metal complexes studied here, the Zn(II) complexes have the largest values of interactionenergies. On the other hand, the values of total interaction energies of [M(edt)۲]۲– and[M(dmedt)۲]۲– complexes are similar or close together and both are larger than those for[M(mnt)۲]۲– complexes. The EDA-NOCV results showed that the electrostatic interactions haveconsiderably more contribution to the total attractive interactions compared to orbital interactionsand, as expected, the contributionof dispersion forces in all complexes is inconsiderable