Jahn-Teller effect analysis at coordination complex [Cu(NH3)4]2+ ion, growth by green synthesis in CuS nanocrystals

Abstract

We present a preliminary theoretical experimental study to explore the molecular distortion of the copper tetraamin coordination complex [Cu(NH3)4]2+ ion, generated indirectly in aqueous solution at CuS(s) synthesis, previously reported. The coordinate covalent bond theory, is applied to understand the chemical kinetics and thermodynamic stability of the ion governed by the distortion of the molecular configuration. The ligands (NH3) located symmetrically at the vertices of the square and Cu2+ cation situated at center, which stabilizes the electric charge and the free electrons which move on the surface up and down the plane of symmetry of the molecular ion, they are kinetically stabilized by Coulomb barriers. Here, we apply the standard theoretical model for a particle confined in a planar-square potential, considering in principle that it achieves greater relative thermodynamic stability associated with the Jahn-Teller effect. The system reaches the energy level with the minimum relative associated with molecular distortion, which favors crystalline growth, slowly generating CuS(s) nanocrystals. This fact is confirmed with X-ray diffraction (XRD) experimental. The hexagonal crystalline phase with average grain size located at ~3.7–5.7 nm is identified and confirmed by results located at ~4.0–7.0 nm obtained by TEM. By modeling a particle confined in a planar-square potential, degenerate energy levels are quantified. Finally, the kinetic mechanism of crystal growth of CuS(s) nanocrystals can be considered a first-order reaction.