The coordination geometry of the iron III ion in iron III tetraphenylporphyrin complex is typically square planar. The iron III ion is coordinated to the four nitrogen atoms of the porphyrin ring, which are arranged in a planar square configuration.Several factors can affect the coordination geometry of the iron III ion in this complex:1. Steric factors: The presence of bulky substituents on the phenyl rings or the porphyrin core can influence the coordination geometry by causing steric hindrance, which may lead to a distorted square planar geometry or even a change to a different geometry.2. Electronic factors: The electronic properties of the substituents on the phenyl rings or the porphyrin core can also affect the coordination geometry. Electron-donating or electron-withdrawing groups can alter the electron density around the iron III ion, potentially leading to changes in the geometry.3. Axial ligands: In some cases, an additional ligand can coordinate to the iron III ion in an axial position, resulting in a five-coordinate square pyramidal geometry or a six-coordinate octahedral geometry if two axial ligands are present. The nature of the axial ligand s and their interaction with the iron III ion can also influence the coordination geometry.4. Solvent effects: The solvent used in the synthesis or study of the complex can have an impact on the coordination geometry. Some solvents can coordinate to the iron III ion, potentially leading to changes in the geometry.5. Temperature and pressure: Changes in temperature and pressure can affect the coordination geometry by altering the relative energies of different geometries, potentially leading to a change in the preferred geometry.