Coordination of methylene blue to group 11 and 12 transition metals: A DFT study

• Published in: Inorganica Chimica Acta Vol. 489; pp. 191 - 197
• Main Authors: da Silva, Talis Uelisson, da Silva, Everton Tomaz, Machado, Sérgio de Paula
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.04.2019; Elsevier Science Ltd
• Subjects: Chemical bonds; Complex formation; Coordination compounds; Copper; Density functional theory; Electrostatic bonding; Gibbs free energy; Group 11 and 12 transition metals; Isomers; Ligands; Mathematical analysis; Metals; Methylene blue; Methylene blue complexes; Periodic table; Silver; Solvent effect; Solvents; Transition metals; Vapor phases; Coordination compounds; Methylene blue complexes; Group 11 and 12 transition metals
• ISSN: 0020-1693; 1873-3255
• DOI: 10.1016/j.ica.2019.02.026

[Display omitted] •Possible coordination modes of methylene blue to cations from groups 11 and 12.•Cu+ complex is more easily accessible than the others.•Reactions are favorable in gas phase and unfavorable in water.•External factor is required for MB effective coordination. Density functional theory (DFT) was used to investigate the possible coordination modes of the methylene blue ligand (MB+) to transition metal cations with the d10 configuration in groups 11 and 12 of the periodic table. Calculations were done in the gas phase and with a water solvent effect. The results showed that MB+ is not a good ligand and can only form complexes by coordination to metals using the N atom of a tricyclic ring. The bond by the S atom makes MB+ act only as a counter-ion in purely electrostatic bonding. Complex formation for Cu and Ag metals were observed only in solvent effect calculations, showing that external factors are needed for the structure’s formation. The relative Gibbs free energy values of the structures showed that there was competition between the complexes and their respective salt isomers, making the formation of both species possible. For other metals, the results showed that the formation of (MB)[MCl2] and (MB)[MCl3] salt types are the only ones possible. However, the absolute Gibbs free energy values for all structures showed that the reactions are favorable in gas phase and unfavorable with solvent effect, and the Cu complex is more easily accessible than the others.