Several spectroscopic techniques can be used to distinguish between isomers in coordination compounds. These techniques are based on the differences in the electronic, vibrational, or magnetic properties of the isomers. Some common spectroscopic techniques include:1. Ultraviolet-visible UV-Vis spectroscopy: This technique measures the absorption of light in the ultraviolet and visible regions of the electromagnetic spectrum. Different isomers of coordination compounds may have different electronic transitions, leading to distinct absorption spectra. For example, in octahedral complexes, the difference between high-spin and low-spin isomers can be distinguished by the number and energy of d-d transitions.2. Infrared IR spectroscopy: This technique measures the absorption of infrared light due to vibrational transitions in molecules. Different isomers may have different vibrational modes, leading to distinct IR spectra. For example, cis and trans isomers of a square planar complex can be distinguished by the presence or absence of certain vibrational bands corresponding to metal-ligand stretching or bending modes.3. Nuclear Magnetic Resonance NMR spectroscopy: This technique measures the magnetic properties of atomic nuclei in a molecule. Different isomers may have different chemical environments for the same type of nucleus, leading to distinct NMR spectra. For example, in a cis and trans isomer of a square planar complex, the chemical shift of the ligand nuclei will be different due to their different positions relative to the metal center.4. Electron Paramagnetic Resonance EPR spectroscopy: This technique measures the magnetic properties of unpaired electrons in a molecule. Different isomers may have different electronic structures, leading to distinct EPR spectra. For example, geometric isomers of a coordination compound with an unpaired electron can be distinguished by their different g-values and hyperfine coupling constants.5. X-ray crystallography: This technique measures the diffraction of X-rays by a crystalline sample to determine the three-dimensional structure of the molecule. Different isomers will have different crystal structures, allowing for their distinction. For example, the crystal structure of a coordination compound can reveal whether it is a cis or trans isomer, or whether it has a square planar or tetrahedral geometry.In summary, various spectroscopic techniques can be employed to distinguish between isomers in coordination compounds based on their electronic, vibrational, or magnetic properties. These techniques include UV-Vis, IR, NMR, EPR spectroscopy, and X-ray crystallography.