Density functional theory (DFT) (B3LYP/6-311++G(d,p)) calculations of the interacting strength 1,2-dithiolene anionic ligands with the [M(OH 2 ) 4 ] 2+ and [M(OH 2 ) 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(OH 2 ) 6 ] 2+ by a dithiolene anionic ligand (L 2− ) and the second is the substitution of two water molecules from the [M(OH 2 ) 4 L] 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.DFT Study of the Interaction between the Ni 2+ and Zn 2+ Metal Cations and the 1,2-Dithiolene Ligands J. Braz. Chem. Soc. 1162

The B3LYP/6-311++G (d,p) 2+ (M = Mg or Ca) aquacations. Two series of ligands are studied: one with a phenyl ring directly bonded to the S interacting atoms and the other with a substituted ethylene (>C=C<) bonded to the two sulfide groups. These ligands present substituents with distinct induction and resonance electronic donor/acceptor effects. Fundamental characteristics, such as geometry, charges and energy of the complexed aquacations and isolated ligands, are analyzed and rationalized to correlate with the substituents effects and the metal-ligand affinity. The thermodynamic results, energy decomposition analysis (EDA) and natural bond order (NBO) show the chelate effect has an important contribution to complex stabilization and leading to an enhanced knowledge of the metal-dithiolene interaction and coordination affinity between the alkaline earth metals and sulfured ligands.