The coordination geometry of a [Co NH3 6]3+ complex is octahedral. This can be determined using spectroscopic techniques such as UV-vis and IR spectroscopy.In an octahedral complex, the central metal ion in this case, Co3+ is surrounded by six ligands NH3 at equal distances and angles 90 from each other. The coordination number is 6, which is typical for octahedral complexes.UV-vis spectroscopy can be used to determine the coordination geometry by analyzing the d-d transitions of the metal ion. In an octahedral complex, the d orbitals of the metal ion split into two sets with different energies: the lower energy t2g set dxy, dyz, and dxz orbitals and the higher energy eg set dx2-y2 and dz2 orbitals . The energy difference between these two sets is called the crystal field splitting energy o .The UV-vis spectrum of an octahedral complex will show one or more absorption bands corresponding to the d-d transitions. The position and intensity of these bands can provide information about the coordination geometry. For example, a high-energy and weak absorption band is indicative of an octahedral complex, while a low-energy and intense absorption band suggests a tetrahedral complex.IR spectroscopy can be used to determine the coordination geometry by analyzing the vibrational modes of the ligands. In an octahedral complex, the ligands are expected to have specific vibrational modes that can be detected in the IR spectrum. For example, the NH3 ligands in the [Co NH3 6]3+ complex will show stretching and bending vibrations in the IR spectrum. The presence and position of these bands can provide information about the coordination geometry.In the case of [Co NH3 6]3+, the UV-vis spectrum will show a high-energy and weak absorption band corresponding to the d-d transitions, and the IR spectrum will show the characteristic vibrational modes of the NH3 ligands, confirming the octahedral coordination geometry.