The photochemical properties of coordination compounds are determined by the electronic transitions that occur within the complex upon exposure to light. These electronic transitions are influenced by the nature of the metal ion and the ligands surrounding it. In the case of [Fe CN 6]^4- and [Co NH3 5Cl]^2+ coordination compounds, the ligands play a crucial role in determining the electronic transitions and absorption spectra.1. [Fe CN 6]^4- complex:In this complex, the central metal ion is Fe II , and it is surrounded by six cyanide CN^- ligands. The cyanide ligand is a strong-field ligand, which means it causes a large splitting of the d-orbitals of the central metal ion. As a result, the energy difference between the lower-energy t2g and higher-energy eg orbitals is significant.Upon exposure to light, the electrons in the t2g orbitals can be excited to the eg orbitals. However, due to the large energy difference between these orbitals, the complex absorbs light in the ultraviolet UV region, which is not visible to the human eye. Therefore, the [Fe CN 6]^4- complex appears colorless in solution.2. [Co NH3 5Cl]^2+ complex:In this complex, the central metal ion is Co III , and it is surrounded by five ammonia NH3 ligands and one chloride Cl^- ligand. Ammonia is a moderately strong-field ligand, while chloride is a weak-field ligand. The presence of these ligands causes a moderate splitting of the d-orbitals of the central metal ion.Upon exposure to light, the electrons in the t2g orbitals can be excited to the eg orbitals. Due to the moderate energy difference between these orbitals, the complex absorbs light in the visible region of the spectrum. This results in the [Co NH3 5Cl]^2+ complex displaying a color in solution, which is typically yellow-orange.In summary, the photochemical properties of [Fe CN 6]^4- and [Co NH3 5Cl]^2+ coordination compounds are influenced by the ligands present in the complex. The strong-field ligand CN^- in [Fe CN 6]^4- results in a large energy difference between the d-orbitals, causing the complex to absorb light in the UV region and appear colorless. On the other hand, the moderately strong-field ligand NH3 and weak-field ligand Cl^- in [Co NH3 5Cl]^2+ cause a moderate energy difference between the d-orbitals, leading to the absorption of light in the visible region and a yellow-orange color in solution.