Describe the concept of hybridization and its role in explaining the geometry of coordination compounds. Choose a specific transition metal complex (e.g., [Ni(CO)4][Ni(CO)_4][Ni(CO)4] or [Co(NH3)6]3+[Co(NH_3)_6]^{3+}[Co(NH3)6]3+) and explain the type of hybridization involved, the geometry of the complex, and how the ligands influence the hybridization of the central metal atom.