DFT Study of The Interaction between the Ni2+ and Zn2+ Metal Cations and The 1,2-Dithiolene Ligands: Electronic, Geometric and Energetic Analysis

Glauber Melengate,José Siqueira Júnior,Daniel Quattrociocchi,Glaucio Ferreira,Stanislav Stoyanov,Leonardo Costa

doi:10.21577/0103-5053.20190011

Abstract

Density functional theory (DFT) (B3LYP/6-311++G(d,p)) calculations of the interacting strength 1,2-dithiolene anionic ligands with the [M(OH2)4]2+ and [M(OH2)2]2+ complexes (M = Ni and Zn) were performed. Three series of ligands were studied: compounds with an aromatic ring, with an ethylene moiety and with a heterocyclic ring. The ligands have substituents electron donors and acceptors by induction and resonance. Two substitution reactions were studied: the first is the substitution of two water molecules from the [M(OH2)6]2+ by a dithiolene anionic ligand (L2-) and the second is the substitution of two water molecules from the [M(OH2)4L] by another dithiolene anionic ligand. Geometric, electronic and energetic properties of the substituted aquacations are correlated with the metal-ligand affinity. All the substitution processes for both metal cations are spontaneous and are modulated by the electronic effect of each substituent of the ligand. Geometric parameters and chelation angle are correlated with the interaction strength. The energy decomposition analysis (EDA) results show that the electrostatic component is the main stabilizing term for the monosubstituted complexes, while for the disubstituted complexes the covalent term is the main stabilizing component. The polarization term is the main one to describe the covalent character. Natural bond orbital (NBO) shows the acid-base interaction nature of the metal-ligand bond.

Highlights

Metal dithiolene complexes have been extensively investigated since 1960 mainly due to their conducting, optical and magnetic properties.[1,2] They are used in molecular devices, superconductors, dye-sensitized solar cells, catalyst for molecular hydrogen production, electronic recording disks and model compounds of more elaborated architectures, as in the active sites of density functional theory (DFT) Study of the Interaction between the Ni2+ and Zn2+ Metal Cations and the 1,2-Dithiolene LigandsJ
Drzewiecka-Antonik et al.[14] analyzed the complexation of the Co2+, Ni2+ and Cu2+ metal cations with 2,4-dichlorophenoxiacetic acids. It was concluded by a combined density functional theory (DFT) and X-ray absorption near edge structure (XANES) analysis that, after the first and second ligand complexation, both octahedral and square planar interaction geometry can be obtained
Tavassoli and Fattahi[17] studied the interaction between an amino acid and divalent metal cations (Zn2+, Ca2+ and Mg2+). They observed that the electrostatic term is predominant in all metal-ligand interactions, but the strongest interaction occurred with the softest metal cation

Summary

Introduction

Metal dithiolene complexes have been extensively investigated since 1960 mainly due to their conducting, optical and magnetic properties.[1,2] They are used in molecular devices, superconductors, dye-sensitized solar cells, catalyst for molecular hydrogen production, electronic recording disks and model compounds of more elaborated architectures, as in the active sites of DFT Study of the Interaction between the Ni2+ and Zn2+ Metal Cations and the 1,2-Dithiolene LigandsJ. Drzewiecka-Antonik et al.[14] analyzed the complexation of the Co2+, Ni2+ and Cu2+ metal cations with 2,4-dichlorophenoxiacetic acids It was concluded by a combined density functional theory (DFT) and X-ray absorption near edge structure (XANES) analysis that, after the first and second ligand complexation, both octahedral and square planar interaction geometry can be obtained. The metal-ligand affinity can be described in terms of geometrical (distance and angles), electronic (charge on specific atoms) and energetic (Gibbs free energy change, energy decomposition analysis, highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energies) parameters. All these terms correlate with the intensity of metal-ligand binding. Electron donor groups enhance the metal-ligand affinity, while electron withdrawing groups weaken the interaction

Methods

Results

Conclusion