The photochemical behavior of coordination compounds and organic molecules differs significantly due to their distinct electronic structures, absorption properties, and subsequent photochemical reactions. Let's discuss these differences and provide examples for both types of compounds.1. Electronic structure and absorption properties:Coordination compounds consist of a central metal ion surrounded by ligands, which can be anions, neutral molecules, or even organic groups. The electronic structure of these compounds is primarily determined by the interaction between the metal ion's d-orbitals and the ligands' orbitals. As a result, coordination compounds exhibit d-d transitions, charge transfer transitions ligand-to-metal or metal-to-ligand , and ligand-centered transitions.Organic molecules, on the other hand, are primarily composed of carbon, hydrogen, and other non-metal atoms. Their electronic structure is based on the arrangement of and bonds. Organic molecules exhibit -* pi to pi-star and n-* non-bonding to pi-star transitions.Examples:- Coordination compound: [Fe CN 6]3- hexacyanoferrate III exhibits a metal-to-ligand charge transfer transition.- Organic molecule: Benzene exhibits -* transitions due to its conjugated system.2. Photochemical reactions:Coordination compounds undergo various photochemical reactions, such as ligand substitution, electron transfer, and energy transfer processes. These reactions can lead to changes in the oxidation state of the metal ion, the formation of new coordination compounds, or the dissociation of ligands.Organic molecules, in contrast, undergo photochemical reactions involving the cleavage or formation of chemical bonds. These reactions include photoisomerization, photodissociation, and photocycloaddition. Organic photochemistry often involves the formation of reactive intermediates, such as radicals, carbocations, and carbanions.Examples:- Coordination compound: [Ru bpy 3]2+ tris bipyridine ruthenium II undergoes a metal-to-ligand charge transfer transition upon absorption of light, which can lead to the formation of a long-lived excited state that can participate in electron transfer reactions.- Organic molecule: Upon absorption of UV light, azobenzene undergoes photoisomerization, converting between its cis and trans isomers.The underlying principles behind the observed differences in photochemical behavior between coordination compounds and organic molecules can be attributed to their distinct electronic structures, absorption properties, and the nature of their excited states. Coordination compounds' photochemistry is primarily driven by the interactions between metal ions and ligands, while organic molecules' photochemistry is governed by the behavior of their and bonds and the formation of reactive intermediates.