What is the primary factor influencing term energies in the Tanabe Sugano diagram?

The primary factor influencing term energies in the Tanabe-Sugano diagram is the ligand field strength. This concept is rooted in crystal field theory, where the strength of the ligands' electric fields affects the energy levels of the d orbitals in transition metal complexes.

In a coordination complex, the presence of different ligands can lead to varying degrees of splitting of the d orbitals. Strong-field ligands cause larger energy separations between the d orbitals, which in turn influences the electronic configurations and the resulting term symbols. The Tanabe-Sugano diagram graphically represents these energy levels and shows how they change with varying ligand field strengths, allowing chemists to predict the electronic transitions and magnetic properties of the complex.

While the number of ligands and the metal oxidation state do affect the overall stability and electronic structure of the metal complex, they do not primarily determine the spacing of the energy levels as directly as ligand field strength does. Temperature can influence the population of electronic states but is not a fundamental factor in the construction of the diagram itself. Thus, ligand field strength is central in understanding term energies in relation to the Tanabe-Sugano diagram.