The coordination geometry of the complex [Fe H2O 6]2+ in its ground state is octahedral. In this geometry, the central Fe II ion is surrounded by six water molecules, with each oxygen atom of the water molecule coordinating to the metal ion. The Fe-O bond lengths are approximately equal, and the O-Fe-O bond angles are close to 90 and 180.Upon electronic excitation, the coordination geometry can change due to the promotion of an electron from a lower energy level to a higher energy level. This can lead to a change in the metal-ligand bond lengths and bond angles, which in turn can affect the overall geometry of the complex. For [Fe H2O 6]2+, the most common change upon electronic excitation is from an octahedral geometry to a distorted octahedral or even a tetragonal geometry.UV-Vis spectroscopy can be used to study the electronic transitions in the complex. The d-d transitions in [Fe H2O 6]2+ are spin-allowed, and the complex exhibits characteristic absorption bands in the visible region of the spectrum. Upon electronic excitation, the position and intensity of these bands can change, indicating a change in the coordination geometry.IR spectroscopy can be used to study the vibrational modes of the complex, particularly the metal-ligand bond vibrations. In the ground state, the octahedral [Fe H2O 6]2+ complex will exhibit characteristic IR bands corresponding to the symmetric and asymmetric stretching and bending modes of the Fe-O bonds. Upon electronic excitation, these bands can shift to different frequencies or exhibit changes in their intensities, indicating a change in the coordination geometry.In summary, the coordination geometry of the [Fe H2O 6]2+ complex in its ground state is octahedral. Upon electronic excitation, the geometry can change to a distorted octahedral or tetragonal geometry. Spectroscopic techniques, such as UV-Vis and IR spectroscopy, can be used to study these changes by monitoring the electronic transitions and vibrational modes of the complex.