Thermodynamic and mechanistic features of the chalcogen exchange reaction between [RGa(μ3-Te)]4 and elemental sulfur or selenium have been studied employing density functional theory (DFT) calculations using the BL3YP basis set and Stuttgart pseudopotentials. For [MeGa(μ 3-E)]4 (E = S, Se, Te) the correlation between the calculated parameters and diffraction data for their isolable analogs is greater than 98%. Each step of the conversion of [MeGa(μ 3-Te)]4 to [MeGa(μ3-E)]4 via [Me4Ga4(μ3-Te)4-x(μ 3-E)x] (E = S, Se) is predicted to occur as a series of isolated reactions. The entropy change for each chalcogen exchange is small in magnitude and corresponds to the degree of cage distortion within the cubane molecules. Calculations performed on [MeGa(μ3-Te)] 4⋯S8 and [MeGa(μ3-Te)]4-S suggest that an increase in electrophilicity of the gallium next to a surface bound tellurium may result in nucleophilic cage opening for which intermediate structures are calculated.
- Chalcogenide exchange reactions
- Density functional theory