Exploring the Potential Energy Surface of Trimetallic Deltahedral Zintl Ions: Lowest-Energy [Sn6Ge2Bi]3– and [(Sn6Ge2Bi)2]4– Structures

• Published in: Inorganic chemistry Vol. 58; no. 15; pp. 10057 - 10064
• Main Authors: Báez-Grez, Rodrigo, Garza, Jorge, Vásquez-Espinal, Alejandro, Osorio, Edison, Rabanal-León, Walter A, Yañez, Osvaldo, Tiznado, William
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 05.08.2019
• ISSN: 0020-1669; 1520-510X
• DOI: 10.1021/acs.inorgchem.9b01206

The synthesis and structural characterization of the dimer [(Sn6Ge2Bi)2]4– raise the possibility of obtaining a broad variety of analogous compounds with different Sn/Ge/Bi proportions. Several combinations of nine atoms have been detected by electrospray mass spectrometry as potential assembly units. However, [(Sn6Ge2Bi)2]4– remains as the unique experimentally characterized species in this series. This fact has motivated us to explore its potential energy surface, as well as its monomers’ [Sn6Ge2Bi]3–/2–, in an effort to gain insight into the factors that might be privileging the experimental viability of this species. Our results show that the lowest-energy [Sn6Ge2Bi]3– structure remains in its oxidized product [Sn6Ge2Bi]2–, which corresponds to that identified in the dimer [(Sn6Ge2Bi)2]4–. Additionally, local minima, very close in energy to the lowest-energy monomer, are chiral mixtures that dimerize into diverse structures with a probable energetic cost, making them noncompetitive isomers. Finally, the global minimum of the dimer [(Sn6Ge2Bi)2]4– presents the most stable monomers as assembly units. These results show the importance of considering the simultaneity of all of these conditions for the viability of these types of compounds.