Changing the ligand in a coordination compound can significantly affect the compound's properties, such as its stability, reactivity, color, and magnetic properties. This is because the ligands play a crucial role in determining the electronic structure and geometry of the coordination compound.When a ligand is replaced with another, it can lead to changes in the following properties:1. Stability: Different ligands have varying abilities to form stable complexes with the central metal ion. The stability of a coordination compound depends on the strength of the metal-ligand bond, which is influenced by factors such as charge, size, and electronegativity of the ligand.2. Reactivity: The reactivity of a coordination compound can be affected by the type of ligand attached to the central metal ion. Some ligands can make the compound more susceptible to substitution reactions, while others can make it more resistant.3. Color: The color of a coordination compound is determined by the electronic transitions between the d-orbitals of the central metal ion. Changing the ligand can cause a shift in the energy levels of these orbitals, resulting in a change in the compound's color.4. Magnetic properties: The magnetic properties of a coordination compound depend on the number of unpaired electrons in the d-orbitals of the central metal ion. Different ligands can cause changes in the electron configuration, leading to variations in the compound's magnetic properties.Spectroscopic techniques can be used to characterize the changes in coordination compounds due to ligand substitution. Some common spectroscopic methods include:1. UV-Visible Spectroscopy: This technique can be used to study the electronic transitions in coordination compounds. Changes in the ligand can cause shifts in the absorption bands, which can be used to determine the nature of the new ligand and its effect on the compound's electronic structure.2. Infrared IR Spectroscopy: IR spectroscopy can be used to study the vibrational modes of the ligands in a coordination compound. Changes in the ligand can result in new vibrational bands or shifts in the existing bands, providing information about the new ligand's identity and bonding characteristics.3. Nuclear Magnetic Resonance NMR Spectroscopy: NMR spectroscopy can provide information about the electronic environment around the central metal ion and the ligands. Changes in the ligand can cause shifts in the NMR signals, which can be used to characterize the new ligand and its effect on the compound's structure.4. Electron Paramagnetic Resonance EPR Spectroscopy: EPR spectroscopy can be used to study the magnetic properties of coordination compounds with unpaired electrons. Changes in the ligand can affect the electron configuration and magnetic properties, which can be detected using EPR spectroscopy.By using these spectroscopic techniques, chemists can gain valuable insights into the effects of ligand substitution on the properties of coordination compounds and use this knowledge to design new compounds with desired properties.